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AVR GCC Tutorial (WinAVR)

1. OLDO m e JD ODl e OD m e OD m External pin 1 positive flank Thus in order to generate a clock from CK 1024 to we use the following instruction TCCRIP SENE CST ST Now the reference value must be only specified We write these into the 16 Bit timer Counter output Compare register OCRIA OCRIA XXx The following diagram is to point the connection out between the reference value and the generated PWM signal FuseeouRie nha Conmter Hon Inverted Pti 7577 Fefrence vahie RERESET Conmter Pitt Signal Pulse Width Oh nearly I would have forgotten The generated PWM Signal spent at the output Compare pin OC1 of the timer and unfortunately to know we therefore also with AT90S23 13 only an individual PWM signal with this method to generate Other AVR types order over up to four PWM outputs The timers Counter of the AVR The today s microcontrollers and in particular the RISC AVRs are too fast for many control problems If we want to let an LED or a lamp flash for example we cannot use naturally the CCU frequency since then nothing more would be to be noticed from flashing to We need thus a possibility of accomplishing procedures in time intervals which are smaller than the clock frequency of the microcontroller Of course the resulting frequency should be also still as exact and stable as possible Here the timer Counter existing in the AVR 1s used A timer is completely simply a certain register in
2. typedef unsigned char Byte J PECCO UL O C OU Secink 1 typedef unsigned short WORD Tf DArCo Un eO e o S i typedef unsigned long DWORD Tear Wintel O E E gt typedef unsigned long QWORD V7 better Minos C out lt SCa nL BYTE The data type BYTE defines a variable with 8 bit width for the representation of whole numbers within the range between 0 255 WORD The data type WORD defines a variable with 16 bits long for the representation of whole numbers within the range between 0 65535 DWORD The data type DWORD spoken Double Word defines a variable with 32 bits long for the representation of whole numbers within the range between 0 4294967295 QWORD The data type QWORD spoken Quad Word defines a variable with 64 bits long for the representation of whole numbers within the range between 0 18446744073709551615 Additional functions into the Makefile Libraries Libraries a files ADDs In order ton use functions from Libraries genuine Libraries a files the linker the names OF the Libraries of acres tons handed over tons that as parameter In addition the option is intended 1 small L tons which the name OF the LIBRARY 1s attached It is tons noted that the name the LIBRARY and the file name OF the LIBRARY of acres emergency identical Behind indicated name corresponds ton the file name OF the LIBRARY without the characters sequence lib RK the beginning OF the file name and without the ending
3. AVR GCC Tutorial WinAVR Early before alpha Version 1 00 This a Google translation for the famous German Wiki tutorial to be found in www mikrocontroller net By takashi Some plapla if you do have some time If not send this section to hell Don t say I did not warn consider this a useful LIFE amp Technical experience The story contains some fancy not a 100 reality just to be truthful some salt amp sugar to make a nice taste The Hard Times story by takashi Hello everybody I was asked for a college project using AVR s microcontrollers so I started making some shopping buying the STK 200 300 kit programmer and a parallel port cable about 100 L E 16 surfing the web for necessary software and seeking knowledge that can be found in any site I forgot to tell you that it was the first time for me to program a microcontroller ever The decision was made to use the C language as everyone out there is saying it s easier So again i surfed the web to find some C compiler out there and so sad every one out there want you to PAY actually I found after that I was wrong amp this was not in my options So I was so pleased to find some Gnu solution out there amp that was the WinAVR plug in for the AvrStudio I forgot also to tell you that I know almost nothing about how to use the C language except for an ill course in a previous semester and of course programming the AVR with
4. AVRDUDE_ FLAGS U efuse w S TARGET efuse hex EL The target clean must still around the lines S REMOVE TARGET lfuse hex S REMOVE TARGET hfuse hex S REMOVE TARGET efuse hex are extended even if the Fuse files are to be deleted Around now the Fuse bits of the attached MICROCONTROLLER to program must be only started make lfuses make hfuses or make efuses With the Fuse bits special caution is required since these can make a programming of the MICROCONTROLLER impossible Program thus only if one has a HV programmer handy or a few reserve AVRs In order to be able to describe further the normal Flash it is important for the target hex in the Makefile not only R eeprom as parameters to hand over separate additionally still to R of fuses R of efuses R of hfuses Otherwise AVRDUDE of problems gets these sections in the Flash where they do not belong to write See also Comparison of the Fuses with different programs External reference tension of the internal analogue digital converter The minimum external reference tension of the ADC may be not arbitrarily low see in addition most current the data sheet of the used MICROCONTROLLER e g with the ATMEGA8 it may not fall below 2 0V according to data sheet S 245 table 103 line VREF NOTE this information is only in the last revision Rev 24860 10 04 of the data sheet After my own
5. Inline assembler Inline assembler offers itself 1f only few assembler directives are needed Typical application are short code sequences for time critical operations in interrupt routines or very precise waiting loops e g 1 Wire Inline assembler will become with asm volatile introduced the assembler directives in a character string summarized which is handed over as parameter By colons to be separated the input and output as well as the Clobber list indicated A simple example of Inline assembler is inserting an NOP instruction NOP stands for NO operation This assembler instruction necessarily exactly one clock cycle otherwise does not do anything Meaningful applications for NOP are exact Delay Warte functions retarding the further program execution around exactly 3 Clock cycles 77 acm vola rile Snop aom volaille nop asm volatile nop Further it can be prevented with a NOP that empty loops which are meant as waiting loops are away optimized The compiler recognizes otherwise the allegedly useless loop and produces for it no code in the executable program lei i m o a loop empties during switched on compiler optimization away Optimized fom Vn Ooi OO ae 7 loop Force Ne Opemmizal1on 2 NOP method 7 for en lt 1000 1 8 asm wOlatale NOP alternative method no optimization volatile wit lo E ae Tor G AO a Ooa 7 A further more useful assembl
6. Movs areny2 ptrToArray uint8_t pgm_read_word amp pgmPointerToArrayl ptrToArray does not contain now the start address the byte array pgmFooByteArrayl however direct accesses with this pointer e g temp ptrToArray a not contents of pgmFooByteArrayl 0 would supply but of a storage location in the RAM which has the same address as pgmFooByteArrayl 0 therefore must now the function pgm_read_byte is used which uses the address contained in ptrToArray i and bhe Pilashw accesses ore S05 es alae myByte pgm_read_byte ptrToArrayti ye ma n When wren myeyce 26 Ge 70 ptrroArray uinte e Pom read word YocmroineerArray lily ptrToArray contains now the address of the first element of the byte array pgmFooByteArray2 is there in the second element of the pointer array pgmPointerArray the address of pgmFooByteArray2 put down for O 1 lt 3 14 of myByte pgm_read_byte ptrToArrayti mach which with myByte 30 7 79 Floats and Structs read In order to pick complex data types out Structs not integer data types floats from the Flash auxiliary functions are necessary Some examples example float from Flash Eloat pone loatAwnay o I PROCHEM 12 222 7 5 21 Ves floats from Flash Address ADDR reads and gives these as return VALUE back inline float pgm_read_float const float addr Una Gane Le ceask2 7
7. condition Ob00000001 with 0b00011100 logical or verknuft C and the result 0b00011101 in PortA written D Although in the meantime bit 0 was deleted it is again set according to D Solution types e Registers without special precautions in interrupt routines and in the main program do not change e Interrupts before changes in registers which are changed also in ISRs deactivate cl e Bits individually reset or set sbi and cbi cannot be interrupted Caution only registers in the lower storage area are accessible by means of sbi cbi The compiler can generate only for these sbi cbi instructions For registers outside of this address range MEMORY Mapped registers also for the manipulation of individual bits dependent instructions are produced lds sts e see also Documentation avr libc of the Frequently asked Questions questions No 1 and 8 conditions avr libc verse 1 0 4 What makes the main program In the simplest exception case nothing at all more It is thus quite conceivable to write a program which remains 1n the Main function only still the interrupts activated and then in a continuous loop All functions are then processed in the ISRs This proceeding is however bad with most applications in addition one gives away one processing level and has possibly problems by interrupt routines which need too much working time Normally one will let the operations absolutely necessary with the occurrence of t
8. different function mode include lt avr interrupt h gt Vee void XXX Vect vold _ atirib te interrupis void xxx v Ci void 4 a j Here stands for XXX for described the name of the vector the above thus e g void TIMERO_OVF_vect void The difference compared with ISR is that when calling the function global the Enable interrupts bits become certified here automatically again set and thus further interrupts This can to not insignificant problems of in the simplest case a stack OVERFLOW up to other unexpected effects lead and should really be used only if one 1s absolutely safe itself to have the whole also in the grasp See also References in AVR GCC See in addition http www nongnu org avr libc user manual group _avr__interrupts html Data exchange with interrupt routines Variable one both in interrupt routines ISR interrupt service routine s and by the remaining program code to be written or read volatile must be defined with Thus it is communicated to the compiler that contents of the variables before each read access are read from the memory and written after each write access into the memory Otherwise the compiler could not optimize the code so that the value of the variables becomes only buffered in processor registers those anything by the change elsewhere received For illustration a code fragment for a push button denounce with recognition is enough for pressed key Me LUGS lt
9. spend however a nice warning The program would hang itself up in here and would turn eternally in the loop And here the Watchdog comes exactly to the course How now does the Watchdog function The Watchdog contains a separate timer Counter which with an internally produced clock by 1 MHz with SV Vcc one clocks Some microcontrollers have their own Watchdog oscillator e g the Tiny2313 with 128 kHz After the Watchdog was activated and the desired prescaler was adjusted the Counter from 0 begins to count up If now the number of cycles stopped depending upon prescaler were reached the Watchdog releases a RESET In order to thus prevent now in the normal operation the RESET we must regularly again start and or reset the Watchdog Watchdog RESET This should happen within our major loop In order to prevent an unintentional switching of the Watchdogs off a special Procedure must be used in order to switch the WD off First the two bits WDTOE and WDE in an individual operation thus not with sbi must be set to 1 Then the bit WDE must be set to 0 within the next 4 clock cycles The Watchdog control register Watchdog timer control register In this register we adjust as we would like to use the Watchdog The register is developed as follows Bit 716 5 4 3 2 l 0 Name WDTOE WDE WDP2 WDP1 WDPO R W RRR RW RW RW RW R W Initial value 0 0 0 0 0 0 0 0 WDTOE Watchdog turn off Enable This bit must be set if the
10. 0 0 000 0 0 0 COM1A1 COM1A0 Compare match control bit These 2 bits determine the action which is to be implemented at the output pin OC1 if the value of the data pointer reaches timers Counter 1 the value of the comparison register thus a Compare so mentioned match arises The pin OC1 PB3 with 2313 must be configured with the data direction register as output COMI1A1 COMI1AO Result 0 0 Output pin OC1 is not headed for 0 l The signal at the pin OCI is inverted Toggle l 0 The output pin OC1 is set to 0 l l The output pin OC1 is set to 1 TCCRIA l l l In the PWM mode of operation these bits have another function COMIA1 COMI1AO Result 0 0 Output pin OC1 is not headed for 0 l Output pin OCI is not headed for During counting up if the value in the comparison register is reached and then the pin OCL is set to 0 l 0 During the Herunterz hlen if the value in the comparison register is reached then the pin is set to 1 One calls this not inverting PWM During counting up if the value in the comparison register is reached and then the pin OC1 is set to 1 l l During the Herunterz hlen if the value in the comparison register is reached then the pin is set to 0 One calls this inverting PWM PWM11 PWM10 PWM mode SELECT bit With these 2 bits the PWM mode of operation timers Counter 1 is steered TCCRIB PWM10 PWM11 Result The PWM mode of operation is not activated Timers Counter 1 works as norma
11. C language is just as ascending to the moon on your foot And of course the WinAVR documentation is useless for me So again started googling for some easy in depth tutorial to help me get rid of this project headache After several hours of internet mess I failed to find any thing in English except for this German tutorial and of course all what I know in Germany is ich libe dich So it seemed like a big nightmare but thanks god I discovered the web page translation tool that Google provides For the first moment I thought that this Google tool would add to my misery to be misery misery however to translate a single word sounds good but automatic translation for a complete web page seems a little bit fancy The least thing you may face is some type of cryptic translation that would make your misery So in a desperate moment I decided to give it a try I will not lose anything any way typing the URL pressing the translate button and the big surprise I was in front of a nice neat translation that is far away beyond my dreams Gohoooooooo Of course it s not yahooooo but after all Google did it Of course not by 100 percent but 85 is fair enough for me to start playing with the WinAVR But Oh Oh Oh no Mr Google you should have been smart enough not to translate the C Code It might not work this way And look to that Google smashed the look and feel of the tutorial The colored Code be
12. FDOND sleep_mode code here only after occurrence of an appropriate i nakaa ue Tmeererite saint enea In older Versions of avr libc not all AVR microcontrollers were headed for correctly by the sleep functions With avr libc 1 2 0 the number of supported types was extended however clearly With non supported types one achieves desired functionality by direct bit manipulation of the appropriate registers see data sheet and call of the Sleep instruction via Inline assembler Fi Glue say r o le Sleep mode power save with the ATmegal69 manually activated MORTE lt 5 10 lt E asm volatile Sleep e see also Documentation avr libc the section Modules power management and Sleep mode The Watchdog And here the ultimate means comes against the incompleteness of us programmers the Watchdog So much we are also exerted for us it is hard to succeed developing absolutely perfect and error free program The Watchdog cannot help us also to better programs however it can ensure that our program if it said good bye again it is started again as a RESET of the microcontroller is released We regard nevertheless once the following code sequence Gneo Ie ox x 10 while x gt 0 i Oo enh at If we look at the loop to we should notice that the same loop is never terminated Why not Completely simply because as unsigned defined variable can never become smaller than zero the compiler should
13. Inline assembler Assembler files Assembler files receive the ending S large S and are listed separately into makefile according to WinAVR mfile collecting main behind ASRC by blanks In the example a function superFunc which switches all pins of the Port D to exit a function ultraFunc which switches the exits according to the handed over parameter a function gigaFunc which returns the status of Port A and a function addFunc which adds two bytes to a 16 bit Wort The assignments in the C code PORTx prevent the fact that the compiler calls away optimized and serves only for the illustration of the parameter transfers First the assembler code The file name is useful S HG Gde aye are lan en workreg workreg2 16 Wa i ALLOUT Oxff fy yd global superFunc func superFunc SUDCrCE UMG push workreg ldi workreg ALLOUT out _SFR_IO_ADDR DDRD workreg beachte pop workreg Tez endfunc ah global ultraFunc Eune vulirarune jebleeyarsl di UNO out SFR TO ADDR PORID gt 24 ret endfunc ae 1 global gigaFunc Fune Glg Eune gigakunc in 24 _SFR_IO_ADDR PINA SIs endfunc ci ye fi Veh le la global addFunc fune addFunc ercle liabyaker push workreg push workreg2 clr workregz mov workreg 22 add workreg 24 POER OND IDIE adc workreg2 1 vl assumed to be always zero movw r24 workreg pop workreg2 pop workreg SIE endfunc Hf en
14. N tnc lude cE nne D Urne JE ik le Teo OE MANo M CODES the status or Che input pins 2t Pores into the variable foo Foo FINE Vo eee Read a bit The AVR library avr libc places also functions to the inquiry of an individual bit of a register to the order bit_is_set lt Register gt lt Bitnumber gt The function bit_is_set examines whether a bit is set If the bit is set a value is returned not equal 0 Exactly taken it is the priority of the queried bit thus 1 for BitO 2 for Bitl 4 for Bit2 etc bit_is_clear lt Register gt lt Bitnumber gt The function bit_is_clear examines whether a bit is deleted If the bit is deleted thus on 0 a value is not equal 0 is returned The functions bit_is_clear and or bit_is_set are not necessary one can also simple C syntax use which is universally usable bit_is_set e g corresponds thereby register name amp 1 lt lt bit number The result is set to lt gt 0 truly if the bit and 0 wrongly if it is not set The denial of the expression thus Register name amp 1 lt lt bit number corresponds bit_is_clear and returns a value to lt gt 0 truly if the bit is not set e see also bit manipulation Write an I O register To the Write one can set I O registers simply like a variable In source codes which were developed for older versions of the avr GCC avr libc the write access is made by the function outp Current
15. Sees OP b eee a e avellne OulLeloa willie ielP Cline Slice uler arune Ul rorun oo E ER TTT O APPR PORD 24 Io S2 bb out Ose ee 24 pile ret Iro Oo 85 ret COOCOO we ga aUe endfunc condition of PINA return Sejloloall cikcem uae Sie Ue WOphCyeln Ulighe Gigabume in 24 _SFR_IO_ADDR PINA lfa es los aia AOT A ret IREGI 08 95 ret ONONE SEE C IOD endfunc two bytes add and 16 bit Word return Gloloal aclclm wine SEL SickolP Gin ECCIP WING e push workreg Ife Oke os Urs ta ial push workreg2 OO TER PUA rl clr workreg2 207 E o eor re e a mov workreg 22 204 eE T mov io Gala add workreg 24 206 OSTOT add roo aia 4 adc workreg2 1 vl assumed to be always zero ANOS dl ae adc TOA Pees call movw r24 workreg 20a eon oul movw C24 E1k6 pop workreg2 Ze IETS pop vey pop workreg 20e Gag SL pop re TOL ZEO 02795 ret The assignment from registers to parameter number and the registers for the return values are described in registers Usage Guidelines the avr libc documentation See also e Avr libc documentation Related Pages avr libc and assembler programs e Avr libc documentation Related Pages FAQ What of register of acres used by the C compilers Global variables for data exchange Often one does not come around global variables to e g realize in order data exchange between main program and interrupt routines For this one must know in the assembler where ex
16. UDR Jy dI CaA LONN Ero UDR eae Came rerurm This function blocks the program sequence Alternatively the RXC bit in a program loop can be queried and be picked out then only with set RXC bit UDR More elegantly and in most applications the proceeding is more stable to read in and buffer for later processing in an Eingangs buffer FIFO Buffer the received indications in an interrupt routine In addition manufacture and well tested libraries and source code components e g UART LIBRARY of P Fleury Procyon avrlib and some in the Academy of avrfreaks net exist TODO 9bit Software UART If the number of the existing hardware UARTs is not sufficient further interfaces can be supplemented over so called software UARTs There are in addition at least two beginnings e The beginning most usual with AVRs is based on the principle that an external interrupt pin for the receipt RX is used The start element releases the interrupt in which interrupt routine ISR the external interrupt deactivated and a timer activated In the interrupt routine of the timer the condition of the receipt pin is scanned according to the Baud rate After receipt of the stop bit the external interrupt is again activated To send can be made by any pin TX which is set according to the Baud rate and the indication which can be sent to 0 or 1 The implementation is not completely simple it exists in addition however finished libraries e g wit
17. bit WDE is deleted otherwise one the Watchdog is not switched off If the bit is set it is automatically again deleted by the hardware after 4 clock cycles WDE Watchdog Enable If this bit is set then the Watchdog 1s activated The bit can be only deleted as long as the bit WDTOE stands to 1 WDP2 WDP1 WDP0 Watchdog timer Prescaler bit These 3 bits intends the number of oscillator cycles for the Watchdog thus how long it lasts WDTCR Until a RESET is released WDP2 WDP1 WDP0 Number of Type Timeout period with Type Timeout period with cycles Vcc 3V Vcc 5V 0 0 0 16K 47ms 15ms 0 0 l 32K 94ms 30ms 0 l 0 64K 0 19s 60ms 0 l l 128K 0 38s 0 12s l 0 0 256K 0 75s 0 24s l 0 l 512K 1 5s 0 49s l l 0 1024K 3s 0 97s l l l 2048K 6s 1 9s In order to use the Watchdog with the AVR GCC compiler the header file must be merged wdt h include lt avr wdt h gt into the source file Afterwards the following functions can be used e wdt_enable uint8_t timeout Activate the Watchdog and adjust the prescaler to the desired value and or in timeout handed over value into the WDTCR register one registers Some Timeout values are pre defined as constants Possible Time out Worth Constant one Worth Time Out WDTO_ISMS_ 0 15 ms WDTO 30MS l 30 ms WDTO_60MS 2 60 ms WDTO_120MS 3 120 ms WDTO 250MS 4 250 ms WDTO_S500MS 5 500 ms WDTO_1S 6 IS WDTO 2S 7 2s e wdt_disable With this function the Watchdog can be switched off The n
18. counter value then the data pointer in the CCU clock regarded takes the following values C 2 cl C O 1 If the prescaler is adjusted to 8 e g then the data pointer takes the following values C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 cl cl cl cl cl cl cl cl C 0 0 0 0 0 0 0 In the PWM mode of operation this bit does not have a function CS12 CS11 CS10 Clock SELECT bit TCNT1H TCNTIL These 3 bits intends the source for the timer Counter CS12 CS11 CS10 Result 0 0 0 Stop the timer Counter are stopped CCU clock CCU clock 8 CCU clock 64 CCU clock 256 CCU clock 1024 External pin T1 falling flank _ Oo OD Dle m e Cc Ole o r D m External pin T1 rising flank If as source the external pin T1 is used then a flank change is also recognized if the pin T1 Is switched as output Timer Counter Data Registers Timer Counter 1 This is realized as 16 Bit upward counter with writing and read access If the counter reached the value 65535 it begins with the next cycle again with 0 Bit 7 6 5 4 3 2 l 0 Name MSB TCNT1H Name LSB TCNTIL R W R W R W R W R W R W R W R W R W Initial value 0 0 0 0 0 0 0 0 In the PWM mode of operation the register is used as up down counter 1 e the value rises first from 0 until it reached the overflow of 65535 to 0 Then the register counts backwards again to 0 For the selection of the register by the CCU an internal t
19. e The internal reference tension is referred to Vece an external reference tension to GND mass Independently of it digitized tensions are always referred to GND With the ATMEGAS8 the pin AREF is connected e g by 32kOhm with GND 1 e one must this nevertheless extremely low feed impedance also into the computation for a voltage divider include and or can this resistance as R2 equal with use Formula for voltage dividers Udiv U R1 R2 R2 In use of Vcc or the internal reference one recommends to arrange a condenser between the AREF pin and GND The definition which tension reference is used takes place e g with the ATmegal6 with the bits REFS1 REFS0 in the ADMUX register The tension which can be measured must lie in the range between AGND and AREF all the same whether internally or externally The ADC can be used in two different modes of operation Simple transformation single Conversion In this mode of operation the transducer if necessary knocked against by the program for in each case a measurement Freely constantly Free Running In this mode of operation the transducer seizes permanently the lying close tension and writes these into the ADC DATA registers The registers of the ADC The ADC has own registers In the following the description of register of a ATMegal6 which has 8 ADC channels The registers differ however not substantially from those other AVRs see data sheet ADCSRA ADC control and status registe
20. here With WinAVR_ the documentation belongs to the scope of supply and is along installed A version of this Tutorial as pdf to expressions is here available not always on current conditions http www siwaw1 arubi uni kl de avr_projects A VR GCC Tutorial www_mikrocontroller_net pdf Needed tools In order to provide and test own programs for AVRs by means of avr gcc avr libc following hard and software are needed e Kit or Experimental board for an AVR microcontroller which is supported by avr GCC compiler all ATmegas and most AT90 see documentation avr libc for supported types This test board can be soldered or also developed on a patch board Some descriptions of registers in these Tutorials refer at90S2313 to be outdated in the meantime The by far largest part of the text is however valid for all microcontrollers of the AVR family Useful test platform are also the STK500 and the AVR Butterfly of Atmel more e The avr GCC compiler and avr libc Free of charge available for almost all platforms and operating systems For Ms Windows in the package WinAVR for Unix Linux see also notes in the article AVR GCC e Programming software and hardware e g PonyProg see also Pony Prog Tutorial or AVRDUDE with STK200 Dongle or the hard and software available of Atmel STK500 Atmel AVRISP AVR Studio e Not necessarily but for the simulation and for debugging under Ms Windows quite useful AVR Studio see section Exploring Makef
21. is offered of realizing software interrupts General Interrupt Flag Register Bit 7 6 5 43 2 1 0 Name INTF1 INTFO R W RW RW R RRRRR Initial value 0 0 0 00 0 0 0 INTF1 External Interrupt Flag 1 This bit is set if by the INT1 Pin an interrupt condition according to the configuration is recognized If that is set global to Enable interrupt flag the interrupt routine is started The flag 1s deleted automatically if the interrupt routine 1s terminated Alternatively the flag can be deleted by the value 1 one writes INTF0 External Interrupt Flag 0 This bit is set if by the INTO Pin an interrupt condition according to the configuration is recognized If that is set global to Enable interrupt flag the interrupt routine is started The flag is deleted automatically if the interrupt routine is terminated Alternatively the flag can be deleted by the value 1 one writes MCU control register The MCU control register contains control bits for general MCU functions Bit 7 6 5 4 3 2 l 0 Name SE SM ISC11ISC10 ISC01 ISCO00 R W R R R W RW RW RW RW R W Initial value 0 0 0 0 0 0 0 0 SE Sleep Enable This bit must be set in order to be able to shift the microcontroller with the SLEEP instruction into the sleep condition In order not to switch the sleep mode on erroneously is recommended to set the bit only directly before execution of the SLEEP instruction SM Sleep Mode This bit determine
22. is called itoa Integer ton of ASCII One must the function a storage area for processing more buffers with place for all numbers which stringer end characters 0 and possibly the sign make available inowelbipkelaurceone ei lations le ee Vj here uart inil Uar LULO Udart Pus 3 0 ToL manod Char s Dae Wiese the So Aa Wart AALI ihu d dyes OM 7 0 Ger fai gt Geetnal system E caa ee ss itoa a pointer on the beginning of s returns there shortened also Uart puto coa a aSa a while 1 return 0 never reached For unsigned 1 6bit Ganzzahlen uint16 t existed utoa The functions for 32bit Ganzzahlen int32_t and uint32_t are called toa and or ultoa Since 32bit Ganzzahlen can exhibit more places an accordingly larger buffer memory is to be planned Also floating point numbers float doubles can be converted with breits existing functions into character sequences in addition the functions dtostre exist and dtostrf dtostre uses exponential way of writing engineering format Reference z Zt existed counted in the avr GCC no genuine double internally always on simple accuracy accordingly float dtostrf and dtostre need libm a avr libc In use of Makefiles the parameter is Im in in LDFLAGS to indicate standard in the WinAVR mfile Makefile were present One uses AVRStudio as IDE for the GNU compiler GCC Plugins is libm a under Libraries to be selected Proj
23. its 16 bit label without H and or L are addressed is automatic the protection temporary of the register from overwriting considers the correct order by interrupt routines to consider nevertheless in the doubt with the write access the interrupts briefly global deactivate In handling 16 Bit registers see also e Documentation avr libc the section Related Pages Frequently Asked Questions No 8 e Data sheet section Accessing 16 bit of register I O registers as parameters and variables In order to be able to hand registers over as parameters for own functions one must hand it as a volatile uint8 t to pointers over For example uinte t Key pressed cComst volatile Uints t Inpulreg Unto t impurbit static uint8 t lasi stale 0 bt Meastostare inoutreg amp la lt inpurtbit a return 07 no change 7 if nevertheless wait to any bouncing past is _delay_ms 20 cond len fOr Next Call notice 7 7 tas 2ta inpourreo il inouriuse 4 depressing and the key return return A Iinpurtr g Ck lt i mo Um base he 77 example of a TunctCion call 4 7 include lt avr io h gt GNOES EE TOTT i key Sressed PINB PBI Vi eee A call of the function with call by VALUE would cause the following With the function input only one copy of the momentary Port condition is made which does not change independently of the actual condition Port any longer with which the function would be
24. lt avr eeprom h gt the EEPROM definitions macros avr libc merge define Bio TAE lz maximum size of the EEPROM the defr ine ee_dummy 0x000 dummy element address 0 should not be used Toe mine ee_valuel 0x001 a byte variable Oe hime ee_wordlL 0x002 a Wordvariable Lowbyte Cli aS ee_wordlH 0x003 a Wordvariable Highbyte define ee_value2 0x004 a entree byte variable With the macros define ee _valuel one specifies the names and the address of the variables IMPORTANTLY The addresses must be sequential Theoretically the compiler should produce an error message if one uses inadvertently twice the same address for two different variables ee a oe We eee ee IS a ie Pe a ea ye file eeprom c their own project VO TUE IMO EIT a include eeprom h own EEPROM header file merge uint8 t ee mem EESIZE EEMEM ee_dummy 0x00 lee_valuel 0x05 ee_wordi1iL 0x01 ee_word1H 0x00 ee value OxFF By the use array which covers the gesammte EEPROM does not remain for the compiler different one to platzieren than the array in such a way that element corresponds to 0 of the array of the address 0 of the EEPROM I hope only that those change compiler farmer in it nothing As one can also see in the above code listing the procedure has a small hook Variable those are larger than 1 byte must somewhat pedantically be defined That access to the EEPROM of values can e g take
25. microcontroller data sheet and the explanations to the module boot h avr libe Also Application Notes exist in addition with atmel com which is transferable to avr GCC code Why so Complicated in such a way To the topic why the Verabeitung is complicated by values from the Flash memory like that it is here only briefly described The Harvard architecture of the AVR exhibits separate address areas for program Flash and data memory RAM The C standard and the GCC compiler do not plan different address areas One string an uart for example a function const char s and hands over to this function the address of a character string a pointer e g OxOlfe white the function not whether the address shows to the Flash memory or RAM However from the pointer value the number cannot be closed whether a simple zeichen an uart s i or zeichen an uart pgm read byte amp s 1 must to be used in order to spend the ith indication Some AVR compilers cheat somewhat in which they do not only put on the address for a pointer but additionally to each pointer the file place Flash or RAM internally secure With call with pointer parameters apart from the address also the storage area to which the pointer points will then hand over to a function This does not however only have advantages Explanations why this like that is lead here too far see also Documentation avr libc of the sections Modules Program space string
26. salle 2 AE ONSE Cioe o oc ee Cae 6 ea J eCOnvMere loto convert lotoo Daud Paud ile E FPU UAR BEAU PRATE Ien I UeRRA Daud ion UBER Rie Dauda J talternatively include lt inttypes h gt uinclo ie wFoolo uine ie lolmoolhony DESCONTO WEOOTG QxAA55 Je Sone ang i OB i Te eger DEOCH wl Ubiton tl wHoOol Gn o sie 3 yi bE Coley S latte cme E o a eae With some AVR types e g ATmega8 UBRRH and UCSRC the same MEMORY address divide So that the AVR can differentiate nevertheless between the two registers the Bit7 URSEL determines be actually described which register is 7000 0011 0x83 addressed therefore UCSRC and the value 3 and 0000 0011 0x3 addresses UBRRH hands over to 3 and hands likewise the value over With some 16 bit registers in particular those 16 bit timer write accesses are made by the so called temporary register The sequence of the accesses determines when the value is actually written in the register Typically only the High byte is described xxxH and internally in temporary register buffered After the Low byte xxxL was written the microcontroller with this sets and in temporary the register of buffered value for the High byte the 16 bit register It is to be noted that internally only temporary a register is available which in interrupt routines mglw With another value one overwrites if 16 bit registers are likewise described there avr gcc avr libc if the registers with
27. so called Toolchain is demonstrated Detailed explanations follow in the further sections of these Tutorials The program is to switch some outputs OFF and others ON in an AVR microcontroller The example is programmed for an ATmegal6 data sheet can be modified however in a general manner for other microcontrollers of the AVR family First the source code of the application which in a text file with the name main c one stores all indications between diagonal stroke star and star diagonal stroke are only comments line comments are likewise possible all indications of a line following on the two diagonal strokes are comment eae Ibias anyan ae da ee a Ine maina Col ee DDPB Oxre 3 equal to DDRB 0b11111111 PORTB 0x03 4 equal to PORTB 0b00000011 while l1 i 3a empties Loop 5b Li ae VO Mewer shea eneo 77 ro V7 Co e In line marked with 1 a so called header file is merged In io h the register names are defined which are used in the later process e The actual program begins with 2 Each C program begins with the instructions in the function Main e The connections of an AVR Pins are combined into blocks such a block is called one port With the ATmegal6 each port has 8 connections with smaller AVRs can have a port also with less than 8 connections be assigned There by definition data sheet all set bits in a direction register make the appropriate connec
28. the type and connection of the programming device is adjusted correctly the transmission can be started with make program by means of AVRDUDE Every other software which can read hex files and to an AVR transfer e g yapp AVRStudio can is naturally likewise used If you started the microcontroller now By Reset pin or Power supply on off the program will make PortB Pins PBO and PBI set to logic 1 One can measure the operating voltage with a measuring instrument now at this connection or let a LED shine do not forget anode to the pin pre resistor At the Pins PB2 PB7 one measures 0 V An LED connected with the anode at one of these connections does not shine Exploring Makefiles If one 1s used to work with integrated development environments just as Visual C The Makefile concept seems at first sight to be somewhat obscure After short training this proceeding is however becomes very handy These files usual name Makefile without file extension serve the flow control of the program make which should be installed on all Unix Linux systems and in a version for Ms Windows also in WinAVR folder utils bin is contained In the folder sample in WinAVR installation you will find one very useful Makefile template which can be adapted simply to your own project local copy conditions September 2004 Alternatively one can use also mfile of your desire Mfile produces a Makefile after user selection or choices in the graphic use
29. 7 2 shops Wore Tloat i u u i 0 pgm_read_word PGM_P addr Ue it pom read word PEM gt addr12 Coeur Uk void egal void CVG ee te dellu renls awn more thie lt Ga f pon read float amp pgmFloatArray i according to f pgmFloatArray iJ Mac mos Cia Ww bie TODO Examples for Structs and pointers out flash on Structs in flash menu state machines etc Simplification for character strings stringers in the Flash Character strings can be proven within the source code as Flash constants In addition the macro serves PSTR out pgmspace h This saves the separate declaration with PROGMEM attribute include lt avr io h gt include lt avr pgmspace h gt fimciude lt string h gt define MAXLEN 30 char StringImFlash PROGMEM Erwin Lindemann in the Flash char StringImRam MAXLEN Vee aes Strepy StringimRam Mueller Luedenschei dt it Le e a Pi S ciamigve E e Sie esligve ai evs S lf macn Whiten TF Che frre st 5 tno Certtons 2qenL cally Pere Toe else the code in here is implemented i Ustincnper stringimRam eo TEAN er Came o the code was implemented here the first 5 indications agrees else with not Uebereinstimmung implemented eee But caution Replaces one for example const char textImFlashOK PROGMEM with jj aban eho ae pee lt 0 tie least a E a through const char textlimFlashProbl
30. AUS end push temp in ten oFR TO ADDR SREG push temp T O2 Bit Counter increment lds temp zaehler 0 inc temp sts zaehler 0 temp brne RAUS lds temp zaehler 1 inc temp sts zaehler 1 temp brne RAUS lds temp zaehler 2 inc temp sts zaehler 2 temp brne RAUS lds temp zaehler 3 inc temp sts zaehler 3 temp brne RAUS ISOS eine out SFR IO ADDR SREG Cemp joo Lene reti a yy ey Jap le importantly Used registers in temp status register SREG secure O Byte low order width unit byte 1 Byte 2 Byte 3 Byte most significant Byte the used registers re establish TODO 16 Bit 32 Bit variable access to arrays stringers Appendix Characteristics with the adjustment existing source code Some functions which were present 1n frihren versions avr libc are regarded in the meantime as outdated They are missing any longer or than deprecated disapproved proven and definitions in lt compat deprected h gt shifted It is advisable not to use existing code to portieren any longer and even the old functions if these are still available Became outdated functions for the declaration of interrupt routines The functions actually macros SIGNAL and INTERRUPT for the declaration of interrupt routines should not be used no more In current versions avr libe e g avr libe 1 4 3 from WinAVR 20060125 interrupt routines which cannot be in
31. O PC6 include ees abo las DDR E VOx00 gt 7 all pine To o nas a momE 37 BORIDI Oa a 7 internals Pull Ups at a i Pores pine aerlvarea 7 DOR 6 Ul DD N tet PC eile Panoaeng PORIC I PC7 internal Pull UP at PC7 activated Debouncing inputs Now all mechanical contacts have are it from switches buttons or also from relays to bounce the unpleasant characteristic This means that when closing the contact the same manufactures not directly contact but several times switches on and off up to final manufacturing of the contact It is to be counted now with a fast microcontroller how often such a contact 1s switched then we have a problem because bouncing is counted as repeated impulses And this phenomenon Must be absolutely considered during the writing of the program aa oe luke eaa Loe ae include lt inttypes h gt irnadef F CPU define F_CPU 3686400UL 7 SOU ae Whee GOO4 M 7 ements include lt avr delay h gt defines _delay_ms off avr libc version 1 2 0 Simple function to denounce a burton 7 Inline uinte t debounce volatile uinte t port uinte t pin de eet OO iam E eia yi a pin was pulled on mass 100ms waits _delay_ms 100 Mea OC i ea ly Ouse give user time for releasing the button delay ms 100 return 1 return O Ae eu a 1hal DOPE S le 2B 0 Pn PEO On a np PUC Ton y Ore Ll lt lt jE Pull up resistance activa
32. SR vect still the names for that are contained Yy oN Oe SOMO Wr le O05 7 107 3077 idle So Oe rE sen moras 7 Avn7 Lome Ce RI Nt one Or Aumegas 7 A Interrupt vectors External Interrupt Request 0 define INTO _vect LVECTOR 1 define SIG _INTERRUPTO VECTOR GL Jo External InN err PE Request l 47 define INT1 vect VECTOR 2 define SIG _INTERRUPTI1 EVECTOR Timer Counter2 Compare Match define TIMER2 COMP vect EVECTOR define SIG_OUTPUT_COMPARE2 EVECTOR e e e e a define TIMER2 OVF vect EVEC HOR 4 define SIG OVERFLOWZ2 vie LOR 4 Timer Counterl Capture Event define TIMER1 CAPT vect EVECTOR 3 define SIG_INPUT_CAPTURE1 EVECTOR Timer Counterl Compare Match A define TIMER1 COMPA vect SVEClOR UG define SIG _OUTPUT_COMPAREI1A VECTOR GG Timer Counterl Compare Match B define TIMER1_COMPB_vect VECTOR 7 define SIG_OUTPUT_COMPARE1B EVECTOR a Possible ones of function trunks for interrupt functions are for example include lt avr interrupt h gt becomes outdated include lt avr signal h gt ISR INT0_vect A PECOS Cucoacca gt STCNAL CIC INTERRUPPE O 47 TEI eaa oE Code 7 Loe TIERO ONE ta vyece yy becomes Cumooteco SC NA SUG lOVEREEOWO 7 Interrupt Code ISR CUSART RX veci becomes outaactced SIGNAL SIG UART RECY 7 Interrupt Code j and so on and so on To the correct way of wri
33. TA registers is updated If the ADIE bit as well as the I bit is set in the AVR status register the ADC interrupt is released and the interrupt handling routine is called The bit is deleted automatically if the interrupt handling routine is called It can be however also deleted as logic 1 is written into the register in such a way it is located in the AVR documentation ADCL ADCH ADIE ADC interrupt Enable If this bit is set and likewise the I bit in the status register SREG then the ADC interrupts activated ADPS2 ADPSO ADC Prescaler SELECT bit These bits determine the division factor between the clock frequency and the input clock of the ADC The ADC needs its own clock for which it produces itself from the CCU Clock frequency The ADC clock should be between 50 and 200kHz The prescaler must be adjusted thus in such a way that the CCU clock frequency results in a value between 50 200kHz divided by the division factor With a CCU clock frequency of 4MHz for example we count begin matrix TF_ min frac CLK 200 mathrm kHz frac 4000000 200000 mathbf 20 TF_ max frac CLK 50 mathrm kHz frac 4000000 50000 mathbf 8o end matrix Thus the division factor 32 or 64 can be used here In the interest of the faster transformation time we will stop the factor 32 here Division factor ADPSO ADPS1 ADPS2 2 0 0 0 2 l 0 0 4 0 l 0 8 l l 0 16 0 0 l 32 l 0 l 64 0 l l 128 l l l ADC DATA regi
34. WM mode of the timer is not active 0 l 8 Bit PWM l 0 9 Bit PWM l l 10 Bit PWM The timer Counter counts now permanently from 0 to the upper limit and again back it as so called up down counters is thus operated The upper limit depends on whether we want to work with 8 9 or 10 bit PWM Dissolution Upper limit Frequency 8 255 frc 510 9 511 frc 1022 10 1023 ftc1 2046 Additionally COM1A0 of the same register the desired output mode of the signal must be defined with the bits COMIALI and COMIA1 COM1A0 Meaning 0 0 No effect pin is not switched 0 l No effect pin is not switched 0 Not inverting PWM The output pin deleted during counting up and set during the Herunterzahlen Inverting PWM The output pin deleted during the Herunterz hlen and set during counting up The appropriate instruction in order to use for example the timer Counter as not inverting 10 bits PWM is called then Old way of writing PWMxx is not any more accepted iE CRAVAS lt lt P Wiel a PMO il e C OMIA New way of writing TCCRIA 1 lt lt WGM11 1 lt lt WGM10 1 lt lt COMI1A1 So that the timer Counter runs at all we must stop in the control register B TCCR1B still the desired clock prescaler and thus also the frequency of the PWM signal determine CS12 CS11 CS10 Meaning 0 0 0 Stop The timer Counter is stopped CK CK 8 CK 64 CK 256 CK 1024 External pin 1 negative flank e O LCUOC D
35. a dummy Readout are recommended one read thus a value and reject this around the ADC warm up to let ADCOPA I aD C V a AC troan oroe von while ADCSRA amp 1 lt lt ADSC A On CONCLUSION Of Che Conv rao Walt j actual measurement average value from 4 following each other transformations Tor ie 4i ADCSRA I 1 lt lt AD5C a transformation single conversion while ADCSRA amp 1 lt lt ADSC T Onm CONCLUSION of CNO Conversion Wale result ADCW jf ChANSTOERMAE1ON Lesults add ADCSRA I ADN ADC deactivate 2 result 4 sum by four divide arithm Average value Teruran resul example Calls VOLA mir ON OL Until adoval adcval Rea C hanne LO 7 M bits on Ub0C00 gt Channel Oey aclewe ll ReadChannel 2 MUX bits on ObO010 gt Channel 2 In the example with each call of the ADC and after the transformation again switched off saves river is activated If one does not want this one shifts with 1 characterized lines into a function adc_init o and deletes with 2 marked lines Analog digital transformation without internal ADC Measure a resistance Analog values can be determined without analogue digital converters also indirectly In the following the measurement of the resistance stopped at a potentiometer is described on the basis the load curve of a condenser With this method only one port pin 1s need
36. a being supposed functions from A LIBRARY with the file name libefsl a linked becomes merged e g READ the appropriate parameters lefsl lake thus Im for tying UP libm a In traditional Makefiles A make variable LDLIBS is used into which l parameter of acres PUT down The WinAVR Makefile collecting Main does emergency contain this variable this represents however NO restriction since all into the make variable LDFLAGS PUT down parameter ton that the linker of acres passed on Examples merging functions from a LIBRARY efsl file name libefsl a LDP LAGS lefsl merging functions from a LIBRARY xyz file name libxyz a LDPLAGS Ixyz If the LIBRARY files do not lie in the standard LIBRARY search path the paths are by means of parameters L to likewise indicate The pre defined search path can by means of avr GCC print search dirs to be indicated As example a project superapp2 in which the source code by two Libraries efsl and xyz and the source code of actual application are put down in different listings with the following tree structure superapp2 eislsourcs im ic lilbetel a xyzsource in at Dibxyz a PSS SS firmware in it application source code and Makefile Hence it follows that in the Makefile the listing and xyzsource are to be taken up efslsource to the LIBRARY search path LDFLAGS L efslsource ll 6 EQ Z SOWIE S S Fus
37. a logic 1 into the appropriate bit one writes TOVO Timer Counter Overflow flag timer Counter 0 This bit is set by the microcontroller if at the timer 0 an overflow of the data pointer takes place The flag is deleted automatically if the associated interrupt vector 1s called It can be however also deleted by logic 1 into the appropriate bit one writes Sleep mode AVR microcontrollers have a set of so called Sleep modes sleep modes These make it possible to switch parts off of the microcontroller On the one hand thereby particularly river can be saved on the other hand can components of the microcontroller be deactivated with battery operation which affects the accuracy of the analogue digital converter and or the analog to Comparators negatively The microcontroller 1s waked by interrupts from the sleep Which interrupts terminate the respective sleep mode is to be taken from a table in the data sheet of the respective microcontroller The functions avr libc are available after merging the header file sleep h oe set_sleep_mode uint8_t mode Sets the sleep mode which 1s activated with call of sleep In sleep h some constants are defined e g SLEEP MODE PWR DOWN The defined modes are not supported however by all simultaneous AVR Controller e Sleep_mode Shifts the microcontroller in with set_sleep mode selected sleep mode tinclude avr 10 h include lt avr sleep h gt Sece eepo dE TEER TNODESEN
38. a program which is to be implemented on an ATmega8 The source code consists of the C files superprog c in it Main uart c Icd c and Iwire c In the source code dierctory are these files superprog c uart h uart c lcd h lcd c Iwire h Iwire c and the Makefile The adopted make file to suit our project http www mikrocontroller net articles WinAVR http www mikrocontroller net wikifiles b b6 Makefile gt http www sax de 7Ejoerg mfile also included in the WinAVR distribution BY THE TRANSLATOR The microcontroller is programmed by means of AVRDUDE over a STK200 Programmierdongle at the interface lpt1 and or dev lp0 In the source code also data for the section are eeprom defined see section of memory accesses these are when programming equal also in the EEPROM to be written Type of microcontroller set In addition the make variable MCU is set according to the name of the used microcontroller List of avr GCC and avr libc supported types is in the documentation avr libc comments in Makefiles begin with the number sign ATmega8 at work MCU atmega8 or MCU atmegal or MCU at J0so 535 i ONG ese Source coding files register The name the source coding file which contains the function Main is assigned to TARGET variable This is however without the ending c IVING dh Soe o ioxe If the project consists as in the example of more than one source coding file the further C fil
39. ace e g radio modem mobile telephones printer sensors intelligent LC displays government inspection department receivers e Field penalty on RS485 RS422 Basis by means of appropriate bus driver components e g MAX485 e DMX Midi etc e LIN bus local Interconnect network Inexpensive sensors actuators in the automotive engineering and beyond that Some AVR microcontrollers already inserted to two full duplexable UART universal Asynchronous Receiver and transmitter hardware UART By the way Full duplex is called nothing else the component can send and receive at the same time Newer AVRs ATmega ATtiny has two USART s or these differ from the UART mainly by internal FIFO buffers for input and output and extended configuration options The buffer size is however only byte The UART is addressed via four separate registers USA RTS of the ATMEGAs have several additional configuration registers The data sheet gives over it information The following table shows only the registers that became outdated the UARTs UCR UART Control Register In this register we adjust as we would like to use the UART The register is developed as follows 0 l 2 3 4 5 6 7 Bit TXB8 RXB8 CHR9 TXEN RXEN UDRIE TXCIE RXCIE Name W R IRW RW RW IW RW RW R W 0 l 0 0 0 0 0 0 Initial value RXCIE RX Complete interrupt Enable If this bit is set a UART RX Complete interrupt is released if an indication became to r
40. actly the variable is stored by the C compiler For this the variable here counters must be called be defined first in the C code as global e g so Pe lude lt avi om aie volatile uinte t zachler intl C malin void any code in which counter can be used In the following assembler example the external Interrupt0 is used in order to count up the counter The initializations of the interrupt and the interrupt enable are missing so correctly meaningfully are the code also not but it shows hopefully like it goes In handling interrupt vectors the same applies as with C with the GCC assembler One must consider the accurate way of writing otherwise not the interrupt vector is put on but a new function and one 1s surprised that nothing functioning see the AVR GCC manual tinaclube arrio nT temp 16 extern zaehler global INTO_vect INTO vect push temp IA in temp SFR_IO ADDR SREG la push temp lds temp zach ler lee inc temp a SES zacoler cee a pop temp out _SFR_IO_ADDR SREG temp Pop eenp reti end Global variables in the assembler file put on Alternatively variables can be put on in addition in the assembler file Thus can be done without a c file For the above example the source text would know then the files zaehl asm S and zaehl asm h to be put down so that only zaehl_asm S with to be compiled would have Instead of referring in the assembler file over the keyword ex
41. ariable F CPU WinAVR 2 2005 In it the clock frequency of the microcontroller is registered in Hertz The definition is available then in the entire project likewise under the designation F CPU e g to derive in order from it UART MIRROR IMAGE or ADC frequency settings The indication has purely a informative character which becomes actual clock rate over the external clock e g quartz and or the attitude of the internal R C oscillator determines The use of F CPU makes thus sense only if the indication agrees with the actual clock Within avr libc starting from version the 1 2 contained in WinAVR starting from 2 2005 the definition of the clock frequency F CPU is used for the computation of the wait functions in avr delay h These function correctly only if F_CPU agrees with the actual clock frequency F CPU must be defined in addition however not necessarily in Makefile It 1s sufficient will however with repeated application unclearly to insert UL before include lt avr delay h gt a define F_CPU here clock in cycles per second See in addition the appropriate section of the documentation Input files for simulation in AVR Studio With older AVR Studio versions one can simulate only on basis of so called coff files Newer versions of AVR Studio starting from 4 10 356 support besides the more modern however still experimental dwarf 2 Format which is produced starting from WinAVR 20040722 avr GCC 3 4 1 Binutils inclusive At
42. atically if the interrupt routine is terminated If in the meantime further interrupts arrive the associated interrupt bits are set and the interrupts on completion of the current interrupt routine in the order of their priority are implemented This can actually lead to problems only if a highly priority interrupt arises constantly and in short consequence This then possibly closes all other interrupts with lower priority This is one of the reasons why the interrupt routines are to be kept very short Interrupt with the AVR GCC compiler WinAVR Functions for interrupt processing are made available in the Inc loading files interrupt h avr libe with older source code additionally signal h ip Tor Sel Clit Une oR je include lt avr interrupt h gt The macro sei switches on the interrupts Actually nothing else is made set as global the interrupt Enable bit in the status register sei The macro cli switches the interrupts off or differently said global the interrupt Enable bit in the status register is deleted CAE Often one stands before the task that a code sequence may not be interrupted It 1s obvious then at the beginning of this sequence cli and at the end is to be inserted This is however unfavorable if the interrupts before call of the sequence were deactivated and afterwards are to remain also further deactivated Is regardless of the previous condition the Interrupts would activate which can lead
43. autiful boxes is now an ugly long line amp amp sadly saying Google translated only 1 9 of the too long 100 paper page fill webpage It was a shock but no desperation with life amp no life with desperation I decided to finish the road that I had started and started with the help of one my friends who is a web designer a hard work My friend started to break up the very long webpage in to smaller pages amp I took those pages and started uploading them on a free web space on the internet amp give the Google webpage translation tool the URL s of the pages by order amp one by one after finishing the translation I started to copy paste the translation to a word document amp started to organize every thing that Google messed the look and feel the nice code boxes the corrupted C Code and hey this word should mean INPUT B not ENTRANCE B amp amp ELF is just ELF not eleven in Germany amp amp Similar actually means Analog amp amp no it s not EXIT Google it s output amp how funny breathing gas is actually ATmegas amp lots of other replacements I had even translated the words in the pictures During this I developed some nice tricks some words Google could not translate it I took those words one by one and put them in Google web search and guess what Google answered me with the famous question Did you mean palapala I took the palapala and try to trans
44. avri Or ae include lt avr interrupt h gt tino lude lt eheicumiohc ale ae a e shore val tes 7 7 Mevouncing define CNIDEBOUNCE 10 V7 ls enOUGi emcees Oo define CNTREPEAT 200 here e g key to Pin2 PortA active low 0 if pressed define KEY_PIN PINA define KEY _PINNO PA2 considers volatile volatile uint8_t gKeyCounter timer Compare interrupt ISR here e g all 10ms implemented IoOR TIMERI COMPA vect is gKeyCounter changed or Remaining program sections must see this change volatile gt current value always into the memory write ie SREY PINGS l lt lt KEY PINON y 4 if gKeyCounter lt CNTREPEAT gKeyCounter i else gKeyCounter 0 P ie Ma lint Void a ae here Initialization of the ports and the timer interrupt Vee one accesses here on more gKeyCounter In addition must the value written in 4 ISR admits Co De volatile gt key always read current value from the memory if gKeyCounter gt CNTDEBOUNCE at least 10 10 ms bounce free if gKeyCounter CNTREPEAT here Code for key is enough pressed else here Code for key briefly pressed j TIT With variables more largely a byte which in interrupt routines and in the main program it is accessed must be paid attention to the fact that the accesses are not interrupted the individual bytes outside of the ISR by an interrupt General plac
45. be runction 16 deleted loop until bric is clear WARTEPIN WARTEBIT Meaning ein sO Standard goes through empties the loop the WAITINGBIT in register WaitingPin oe si chee ay by a clever While WaitingPin amp lt lt WaitingBit More universally and also to other platforms the use of C Standard operators is better transferable See also e Documentation avr libc the section Modules Special Function of register e Bit manipulation Access to Port All Port the AVR microcontroller is steered via registers In addition registers are assigned to each Port 3 Data directions register for PORTx ee x corresponds to A B C D etc dependent on the amount of the Port of the used AVR Bit in the register set 1 for output bit deleted 0 for input Input address for PORTx PINx Condition of the Port The bits in PINx correspond to the condition of the Port pins defined as input Bit 1 if pin high bit 0 if Port pin low Data pointer for PORTx PORT x This register is used in order to head for the outputs of a Port With pins which were switched by means of DDRx to input the internal Pull UP of resistors can be activated or deactivated over PORTx 1 actively Data direction determination First the data direction of the used pins must be determined In order to reach this the data direction register of the appropriate Port is described For each pin which is to be used as output thereb
46. be sent to be written before the actual data byte into the data pointer is written USR UART Status Register Here the UART communicates us which it makes in such a way straight 012 3 4 5 6 7 Bit OR FE UDRE TXC RXC Name RRR RR R RW R RW 000 0 0 l 0 0 Initial value RXC UART Receive Complete This bit is set by the AVR if a received indication were transferred by the receipt shift register into the receive data register The indication must be picked out now as fast as possible from the data pointer If this affected before a further indication completely to receive became an overflow error situation will arrive With the selection of the data pointer the bit is deleted automatically TXC UART Transmit Complete This bit is set by the AVR if in the transmission shift register indications present completely one spent and no further indication in the transmit data register lines up This means thus if communication is at full extent final This bit is important with half duplex connections if the program must switch after sending data to receipt In the full duplex enterprise we do not need to consider this bit The bit is deleted automatically only then if the appropriate Interrupt handler is called otherwise must we the bit delete UDRE UART DATA register Empty This bit indicates whether the send buffer is ready in order to take up an indication which can be sent The bit is set by the AVR 1 if the send
47. ble applications 17 programming with interrupts O 17 1 requirements at interrupt routines 17 2 sources of interrupt 17 3 registers 17 4 general over interrupt processing 17 5 interrupts with the AVR GCC compiler WinA VR 17 5 1 ISR 17 5 2 interruptible Interrupt routine 17 6_data exchange with interrupt routines 17 7 interrupt routines and register accesses 17 8_Which makes the main program e 18 memory accesses O O O 18 1 RAM 18 2 program memories Flash 18 2 1 byte reads 18 2 2 word reads 18 2 3 Floats and Structs read 18 2 4 simplification for character strings stringers in the Flash 18 2 5 Flash in application write 18 2 6 Why so Complicated in such a way 18 3 EEPROM 18 3 1 bytes read write 18 3 2 word reads writes 18 3 3 block reads writes 18 3 4 EEPROM memory map in eep file 18 3 5 EEPROM variable on firm addresses put 18 3 6 acquaintance of problems with the EEPROM functions e 19 the use of printf e 20 assembler and Inline assembler o 20 1 Inline assembler o 20 2 assembler files o 20 3 global variables for data exchange 20 3 1_global variables in the assembler file put on 20 3 2 variables more largely than 1 byte e 21 appendix o 21 1 characteristics with the adjustment existing source code To 21 1 1 functions became outdated for the declaration of interrupt routines To 21 1 2 functions became outdated to the port access To 21 1 3 functions became outdate
48. buffer is empty It is deleted 0 if an indication is present in the transmit data register and were not transferred yet to the transmission shift register Atmel recommends for compatibility reasons with coming uC to set UDRE to 0 if the UCSRA register is described The bit is deleted automatically if an indication 1s written into the transmit data register FE Framing error This bit is set by the AVR if the UART detects an indication framework error 1 e if the stop bit of a received character 0 is The bit is deleted automatically if the stop bit of the received character is 1 OR Overrun This bit is set by the AVR if our program does not fetch the indication lying ready in the receive data register before the following indication completely to receive became The following indication is rejected The bit is deleted automatically if the received indication could be transferred into the receive data register UART DATA Registers Here data are transmitted between UART and CCU Since the UART in the full duplex enterprise can receive and send at the same time it concerns here physically 2 registers which are addressed however via the same I O address According to whether a reading or a write access on the UART taken place the correct UDR is addressed automatically UART Baud Rate Register In this register we must communicate to the UART how quickly we would like to communicate gladly The value which must be written in
49. charge e The use of the MAKE program with suitable Makefiles Integrated development environments differ strongly in your operation and are not also available for all platforms on which the compiler is executable e g AVRStudio only for Ms Windows The use of the avr GCC compiler with IDEs is referred here to their documentation In the following sections the generation of machine code for an AVR hex file from C source code C files is more near described on the basis of the universal and platform independent proceeding by means of make and Makefiles You will find many of the options described here also available at the configuration dialogue of the avr GCC Plugin in AVRStudio AVRStudio generate a Makefile in a folder of the Project directory With the change beginning from the Makefile to WinAVR main collecting to AVRStudio you should know that AVRStudio for AVRStudio version 4 12SP1 with a new project the optimization option see section Exploring Makefiles typically Os adjusts and the mathematical library avr libc libm a linker option lm does not merge Both is standard in use of Makefiles after WinAVR main collecting and should therefore be adjusted manually in AVRStudio at the avr GCC Plugins configuration dialogue in order to produce also with AVRStudio compact code Introduction example In the beginning we will start with a small example with which the use of the compiler and the aid programs the
50. d In the Makefile the name of the assembler source coding file is to be registered ASR The call extern extern extern extern int mal EFTS useful S takes place then in the C code in such a way void SUPeCE UNC Vola VO MiltrakhiIneltUlMrEo sk Seu Vad Lie orn C Chic Mine void Uinell ose adean ibubehe sc me ee n e wie a im Vou SUDeELE UNC 7 Uk rah unc Oss sn PORID PORIA FORIB l SE URTE facie nies ORFO O e OTi addEune OKFO OUl e o The result becomes new evident in the Iss file EETA superFunc 148 Oe 94 f6 00 eau Oxlec Uteealkmame COscSs Lae Somes ikoni a E oS 14e Oe 94 fb 00 Call Oxo PORTD gigaFunc seas Oe 94 fd O00 call 0x lira 15o eZ I5lo ou Ope ie 2 ple PORTA acddPunc UxPO0 0x11 amp OXT Es or 61 el TAr OZ l ele 15a 80 ef tdr ARA T O Ses Oe 94 ff 00 Call Oxlfe 160 clo DO out oe S e w PORTE adaFune OrFO OIN ys I A ol el VAr ro Oxi T 164 80 ef leak 2 Ae Oran 2AO IGG Cer a 700 Cali Ooi loa oom E mov Lom o oo On eor iOS MOP ANS loe ec aS out le e aoa ETEN 00000lec lt SuperFunc gt sets all pins of PortD on exit Gloloal Susser tine LUNO Sue era ume SUNOS ie le WN amp push workreg lec OTOS IU Sia ANG ldi workreg ALLOUT lee Of ef ikea TOMS Oon eer Out vot RT IO ADDR DDRD werkred IEE Of bb une Or albu eee roel pa leg pop workreg BEZ Or pop rlo Ter 1f4 OSTO ret 00000 EGS lt utteraFunc gt endfunc
51. d Before the access to one of these registers Besides first OCR1L and only thereafter OCR1H must be selected If into the register is to be written all interrupts must likewise become closed Then first the OCR1H Register and only thereafter the OCR1L Register must be written thus exactly the reverse sequence as during the reading of the register Timer Counter Input Capture Registers timer Counter 1 Bit 7 1061 514 321 0 Name MSB ICRI H Name LSB ICRI L R W R RRRIRRIR R Initial value O 0500 0 0 0 0 The input Capture register is a 16 Bit register with read access It cannot be described If by the input Capture pin ICP the flank defined in accordance with parameters in the TCCRIB is recognized then current contents of the data pointer TCNT1H TCNTIL are copied immediately into this register and the input Capture flag ICF1 in the timer interrupt flag register TIFR is set As mentions already above all interrupts must become closed before the access to this register Besides Low and High byte of the register in the correct order must be worked on Read ICRIL gt ICR1H Write ICRIH gt ICRIL The PWM mode of operation If the timer Counter 1 in the PWM mode of operation is operated then the data pointer TCNT1IH TCNTIL and the comparison register OCR1H OCRIL forms 8 9 or 10 bit freely running PWM modulator which can be measured as PWM signal at the OC1 Pin PB3 with 2313 The data pointer TCNT1H TCNTIL is operated t
52. d the mass a Pull down resistance is switched This serves to hold the level during opened switching position logic 0 Pull UP resistors activation Active Low VCC With this method the contact is switched between the input pin of the microcontroller and mass Thus with open switch the microcontroller an undefined signal does not get between supply voltage and the input pin so called Pull UP a resistance is switched This serves to draw the level with opened switch on logic 1 The resistance value of the Pull UP of resistance is not critical actually If it is however too highly selected the effect is possibly not given As usual value 10 Kilo ohms were in practice The AVRs has even at most pins by software insert able internal Pull UP of resistances which we can naturally use The internal Pull UP of resistors from Vcc to the individual Port pins are activated and or deactivated via register PORTX if a pin is switched as input If the value of the appropriate Port pin is set to 1 then the Pull UP resistance 1s activated At a value of 0 the Pull UP resistance is not active One should use in each case either the internal or external Pull UP a resistance but both together In the example all pins of the Port D are switched as inputs and all Pull UP of resistors are activated Further pin PC7 is switched as input and its internal Pull UP resistance is activated without changing the parameters for the other Port pins PC
53. d to the access to bits in registers 21 1 4 self defined non standardized integral data types o 21 2 additional functions in the Makefile 21 2 1 libraries Libraries a files add 21 2 2 Fuse bits o 21 3 external reference tension of the internal analogue digital converter 22 TODO Preface This Tutorial is to facilitate the entrance into the programming of Atmel AVR Microcontroller in the programming language C with the free free C compiler avr GCC This Tutorial presupposes basic knowledge in C Previous knowledge in the programming of micro control learn neither in assembler nor in another language are not necessary The original version comes from Christian Schifferle many new sections and current adjustments from Martin Thomas Many of the functions used in the original document are no more contained in of the current versions of the avr GCC of C compiler and the run time library avr libc or are not to be used no more This Tutorial was adapted to the new functions methods The explanations and examples refer to the versions 3 4 5 of the avr GCC compiler and 1 4 3 avr libc like that as them in WinAVR 20060125 are contained The differences to older versions are described in the main text and appendix is however recommended to beginners to use the current versions In this text becomes frequently on the standard library for the avr GCC compiler which referred avr libc On line version avr libe of the documentation is
54. e AVRs are 8 bit microcontroller To the illustration a code fragments 7 volatile uintl6_t gMyCounterlbo6bit Vee ee IE SIRO eee ea ee GMY CounmterlS6BiEz t eee Mie tier W 140 Ti DEM eee ie wind etCone f not well Mglw here an error if a byte of MyCounter is in tmpCnt copied already however before copying the second byte an interrupt arises which changes contents of MyCounter tmp ne oly Councerl6bic better Changes outside prevent gt all partial bytes remain consistent cli Interrupts deactivate cmp n oMyCounterloOBit sei again activate or previous status of the global interrupt flag remains received vanto amp Sr eg_ tmp sreg_tmp SREG i OPOTeCE1On eee temp nt oMy Colmer OBRIC SREG sreg_tmp Testor ing 77 Interrupt routines and register accesses If registers are changed both in the main program and in interrupt routines it is to be made certain that these accesses do not overlap themselves Only few instructions can be translated into so called atomic accesses which cannot be interrupted by interrupt routines To the illustration an instruction with which a bit and in the connection three bits in a register are set Panelinde eve dere ne Iie Tier in W 1G Ve ee PORTA 1 lt lt PAQ PORTA 1 lt lt PA2 1 lt lt PA3 1 lt lt PA4 T
55. e bit For the computation of the Fuse bits also the AVR Fuse Calculator offers itself apart from the study of the data sheet To be warned must before the use of PonyProg because by the negated representation gladly errors are made there If the programming of Fuse and LOCK bits is to be automated one can likewise make this by entries in the Makefile which is handed over with the call of make program to the used programming software In the Makefile collecting main of WinAVR and mfile there is for it however no filling out assistance conditions 9 2006 The following remarks apply to the programming software AVRDUDE standard in the WinAVR collecting main can be transferred however in a general manner to other programming software which supports the indication of the Fuse and LOCK bit parameters by command line parameter e g stk500 exe In the simplest case one supplements some variables whose values naturally depend on the used MICROCONTROLLER and the desired parameters in the Makefile see data sheet Fuse Lockbits os ae ee Pog amming OPET Ome Wan CUGe ia a ee ee F example f ATmegal6 not simply take over Numerical values is more near described on i the data sheet reconstruct and if necessary change it AVRDUDE _ WRITE _LEUSE UES aw ee ie im AVRDUDE_WRITE_HFUSE UN Use WO lt Gl osm AVRDUDE_WRITE_LOCK U lock w 0x2f m a So that these variables are also used should the call of avrdude in the Makefile acco
56. e g PWM and smoothing Independently of it the possibility naturally always exists of using special components for the analog digital and or digital analog transformation and of heading for these over a digital interface e g MIRROR IMAGE ONE or I2C with a AVR ADC analog digital converter The analog digital converter ADC converts analog signals into digital values which can be interpreted by the microcontroller Some AVR types already inserted a more channel analog digital converter The accuracy with which a analog signal can be dissolved is indicated by the dissolution of the ADC in number of bits one hears and or reads in each case from 8 Bit ADC or 10 Bit ADC or still more highly A ADC with 8 bit dissolution can represent thus the analog signal with an accuracy of 1 256 of the maximum value If we assume now times we would have a tension between 0 and 5 V and a dissolution of 3 bits then the values OV 0 625V 1 25 1 875V 2 5V 3 125V 3 75 4 375 5V could come along see in addition the following table Appropriate measured value Input voltage at the ADC 0 0 lt 0 625V l 0 625 lt 1 25V 2 1 25 lt 1 875V 3 1 875 lt 2 5V 4 Oe ee 2y 5 3 125 lt 3 75V 6 3 75 lt 4 375V 7 4 375 SV The data are naturally only approximate The more highly now the dissolution of the analog digital converter is thus the more bits it has all the more exactly can the value be seized The internal ADC in t
57. eBuffer eeFooByteArrayl sizeof myByteBuffer ie Sand DOW Wd a Oia 7 eeprom_read_block myWordBuffer eeFooWordArrayl sizeof myWordBuffer data LOCK in EEPROM LETTER eeprom_write_block myByteBuffer eeFooByteArrayl sizeof myByteBuffer eeprom_write_block myWordBuffer eeFooWordArrayl sizeof myWordBuffer ee Not Integer data types like e g floating point numbers can be converted quite practically over a union in byte arrays and back changed new This proves here however not only here as useful ee float myHioak 12734 unLron i Elon r uineet eaen hloar i U lee myF loal float 1n EEPROM 47 eeprom_write_block amp u i amp eeFooFloat sizeof float float from EEPROM eeprom_read_block amp u 1i amp eeFooFloat sizeof float lV so Mew 2554 9 eee Also compound types can be processed with the block routines Vy ee typedef struct Uine oie labellel Uine one rom codec E EMY C Buln define MAXSENSORS 3 tMyStruct eeMyStruct MAXSENSORS EEMEM ae void egal void tMystruct work SETOCPY Work label TEluUr GetRomCode work rom_code dummy for illustration Rom code sets J DPEOLECEION Of Work In Ene EEPROM eeprom_write_block work amp eeMyStruct 0 sizeof tMyStruct f Index 0 Ser Ey werk label Bad GetRomCode work rom_code eeprom_write_block amp work amp eeMyStruct 1 sizeof tM
58. eceive from the UART Global the Enable interrupt flag must be naturally also set TXCIE TX Complete interrupt Enable If this bit is set a UART TX Complete interrupt is released if an indication were sent by the UART Global the Enable interrupt flag must be naturally also set UDRIE UART DATA register Empty interrupt Enable If this bit is set a UART data pointer is released empty interrupts if the UART is again ready around a new indication which can be sent to take over Global the Enable interrupt flag must be naturally also set RXEN Receiver Enable Only if this bit is set the receiver of the UART works at all If the bit 1s not set the appropriate pin of the AVR can be used as normal I O pin TXEN transmitter Enable Only if this bit is set the transmitter of the UART works at all If the bit is not set the appropriate pin of the AVR can be used as normal I O pin CHR9 9 bits of character If this bit is set 9 bits long indications can be transferred and received 9 Bit can be used if necessary as additional stop bit or as parity bit One speaks then of a 11 bit indication framework J start element 8 data bits 1 stop bit 1 parity bit 11 bit RXB8 Receive DATA bit 8 If the above mentioned CHR9 Bit is set then this bit contains of 9 Data bit of a received indication TXB8 Transmit DATA bit 8 If the above mentioned CHR9 Bit is set then must into this bit 9 Bit of the indication which can
59. ecessary Procedure as is described above implemented automatically e wdt_reset This is probably the most important of the Watchdog functions It produces a Watchdog RESET which must be implemented periodically before expiration of the Time out time so that the Watchdog does not put the AVR back Of course the WDTCR register can be programmed also with us the already well known functions for the access to registers Watchdog possible applications Whether now the Watchdog is to be used as protective function in first place depends strongly upon application used periphery the range and the quality assurance of the code If one wants to get surely that a program does not get caught in a continuous loop the Watchdog is the suitable mean for this to be prevented Further it can be used with skillful programming to implement certain current savings functions With some newer AVRs e g the ATTiny13 the Watchdog can be used also directly than timer which wakes the microcontroller up from a sleep mode Also this can be adjusted in the WDTCR register In addition the WD offers the only possibility an intended system RESET a correct RESET none jmp 0x0000 without external wiring to release which e g with the implementation of a Bootloaders is useful With certain applications the use of the WD can naturally always serve as ultimate deadlock safety device for not considered conditions as additional safety device It exi
60. ect gt Configurations option gt Libraries merge to the right gt libm a with the arrow include lt stdlib h gt Ve jf Ware Ine Here Mart pure Vara pulls S O 7 es aioli ipe OOCumentar Ton Char GECSeErT double _ val elie Sewicen Char __ prec Char oes vA ite Malin void buffer memory sufficiently largely sign width end characters Char Se PLOC ce va ee a Gare nie eoe ea eh ton oars ae Warr Po o Vj ORo enoe Usart purse O oSer a aa o n while 1 7 return 0 never reached See also e Documentation avr libc stdlib h e The use of printf Receiving Indication To the receipt of indications the receiving element of the UART must be activated with the initialization as the RXEN bit in the respective configuration register UCSRB and or UCSROB UCSR1B is set Waited in the simplest case so long until an indication became to receive this is located then in the UART data pointers UDR and or UDRO and UDR1 with AVRs with 2 UARTS for the order suctions Polling enterprise An example of the ATmegal6 include lt inttypes h gt Pine LUGE aviry mown E O E aa E O 1a lata aS sh e e uses E a DIo esisiel E S mbuas lc a inom Misi aA E a void Usart_EnableRX UCSRB 1 lt lt RXEN yo Ent eCaetons sLecetye 6t7 Hh cmt Usa tte RZ Vold while UCSRA amp 1 lt lt RXC wait for available indications return
61. ed an analogue digital converter or a analog to Comparator is not necessary In addition condenser and the resistance the potentiometer is switched into row between taking precautions tension and Masse GND suctions RC network Additionally a connection of the line between condenser and potentiometer to a port pin of the microcontroller is made The following illustration clarifies the necessary circuit VCC The port pin of the microcontroller on output one configures in the example DDRD 1 lt lt PD3 and this output on logic 1 High PORTD 1 lt lt PD3 switched the same potential VCC rests and the condenser thus unloaded against both plates of the condenser Sounds amusingly with Vee unloaded is at both sides of the condenser the same potential fits however in such a way there and thus a difference of potential of OV exists gt condenser is unloaded After a certain time the condenser is unloaded and the port pin as input is configured DDRD amp 1 lt lt PD3 PORTD amp 1 lt lt PD3 whereby this becomes high impedance The status input pin in PIND is logic 1 High The condenser loads itself now over the potentiometer up the voltage drop over the condenser and that rise over the potentiometer sink Now if the voltage drop over the potentiometer falls under the Threshold spannung of the input pin 2 5 Vcc thus approx 2V the input signal is recognized as LOW bit in PIND becomes 0 The time in
62. efiles offers still many far possibilities some of it in the appendix additional functions in the Makefile is described Integral Integer data types With the programming of controllers the definition of some integral data types is meaningful from which clearly the bit length can be read off Standardized data types are defined in the header file stdint h For the use of the standardized types one merges the definition file as follows off avr libc version 1 2 0 possible and recommended Pinetu Stdint i gt becomes outdated include lt inttypes h gt Some the types defined there avr libe version 1 0 4 typedef signed char int8_t typedef unsigned char uint8_t typedef short inti6_t typedef unsigned short uint16_t typedef long int32_t typedef unsigned long uint32_t typedef long long int64_t typedef unsigned long long uint64_t e Int8 t stands for 8 bits for a Integer with a range of values 127 to 128 e uint8 t stands for 8 bits for a Integer without signs unsigned int with a range of values from 0 to 255 e intl6 t stands for a 16 Bit Integer with a range of values 32767 to 32768 e uintl6 t stands for a 16 Bit Integer without signs unsigned int with a range of values from 0 to 65536 The types without placed in front u are stored signed numbers Types with presented u serve the file of postiven numbers inclusive 0 See also Documentation avr libc the section module it standard Integer of t
63. em PROGMEM with Complies Ware in thew oow mecd RAM 7 texan lash ii Holnts bo em leashedress gt then it can come to problems with AVR GCC To recognize to the fact that the initialization stringer 1s put by textImFlashProblem to the constants to the end of the program code BSS from which it should actually be copied for use in RAM and becomes Since nevertheless the reading code by means of pgm read searches in front in a place in the Flash nonsense is read This seems to be further a problem of the AVR GCC seen with avr GCC 3 4 1 and 3 4 2 with the adjustment to Harvard architecture constant pointer on variable data Remedy Workaround Initialization with character strings with or directly in the code PSTR use One hands over character strings more exact the address of the first indication those in the Flash are abglegt to a function must this be accordingly programmed The function does not have a possibility to differentiate between whether it concerns an address in the Flash or in the RAM Avr libe and many other avr GCC libraries adhere to the convention that names of functions expect the Flash addresses with the suffix p or P are provided A function which spends a stringer put down in the Flash e g to a UART would look in such a way then void uart Pito Const CNar CEL Char indicat ions while indications pgm_read_byte text so long as by means of p
64. emp register is used The same register 1s also used if OCRI or ICR1 one accesses Therefore all interrupts must become closed because otherwise the possibility of the simultaneous access to the temporary register is given what incorrect behavior of the program naturally lead Before the access to one of these registers Besides first TCNT1L and only thereafter TCNT1H must be selected If into the register is to be written all Interrupts must likewise become closed Then first the TCNT1H Register and only thereafter the TCNT1L Register must be written thus exactly the reverse sequence as during the reading of the register Timer Counter Output Compare Registers timer Counter 1 Bit I 6 514 32 l 0 OCRI1H OCRIL ICR1H ICRIL Name MSB OCRI1H Name LSB OCRIL R W R W R W R W R W R W R W R W R W Initial value 0 0 0 0 0 0 0 0 The value in the output Compare register is constantly compared with the current value in the data pointer TCNT1H TCNTIL If the two values agree then a so called output Compare match is released The appropriate actions are stopped over the timers Counter control and status register For the selection of the register by the CCU an internal temp register is used The same register 1s also used if OCR1 or ICR1 one accesses Therefore all interrupts must become closed because otherwise the possibility of the simultaneous access to the temporary register is given what incorrect behavior of the program naturally lea
65. er inline is the call of sleep asm volatile sleep since for this no own function exists in avr libc As example of Inline assembler of several lines a precise Delay function The function receives a 16 bit word as parameter examines the parameter for 0 and terminates the function in this case or goes through the following loop whenever as indicated in the value of the parameter Inline assembler has here the advantage that the running time independently of the optimization stage parameter O see makefile and the compiler version is static Inline vold delay lcooplG urnt lo le count asm volatile cp A0 zero rg n t ope BO __zero_reg__ n t breq 2f n e wi NANE sbiw 0 1 n t torno Ip n t Vo W TEW Count EA count e Each instruction is locked with n t The line makeup communicates to the assembler that a new instruction begins e As branch marks labels numbers are used These special labels are several times in the code usable One jumps back in each case B or forward f to the next ausffindbaren label The result points a view to the assembler file which the compiler with the option save temps does not delete cp r24 __zero_reg__ CDG r295 Zero rgo breg zf T Spin a brne 1b ae Detailed remarks about Inline assembler are in the documentation avr libc in the section of the Related Pages Inline Asm See also e AVR assembler directive list e German introduction to
66. er utilities and section Modules Bootloader support utilities EEPROM One notes that the EEPROM memory permits only a limited number of write accesses If one describes an EEPROM cell more frequently than the number assured in the data sheet typical 100 000 the function of the cell is not any longer guaranteed This applies to each individual cell With skillful programming e g ring buffer with which the cells which can be described is regularly changed can one a clearly higher number of write accesses related to the overall memory achieve Writing and read accesses on the EEPROM memory are made by the functions defined in the module eeprom h With these functions individual bytes data items know 16bit and data blocks to be written and read In the case of use of the EEPROM it is to be noted that before the access for this memory it 1s tested whether the MICROCONTROLLER locked the previous EEPROM operation The avr libc functions contain this examination one must it not implements One should also prevent that that is interrupted access by the processing of an interrupt routine there determines command successions is given which must within fewer clock cycles sequences timed sequence Also this must be implemented on use of the functions from avr libc eeprom h file not Within the functions interrupts before the EEPROM sequence is global deactivated and in the connection if already switched on new activates before Wit
67. ercarrier noise suppressor can be switched on Then when recognizing the flank over 4 clock cycles configured the signal is supervised and released then only if equal all 4 measurements are the appropriate action Common registers Different registers contain conditions and parameters which are both for the 8 bits and for the 16 Bit timer Counter in the same register to be found Timer Counter interrupt MASK Register Bit 7 6 53 4 3 2 l 0 Name TOIE1 OCIE1A TICIE TOIEO R W R W R W RR RW R RW R Initial value 0 0 0 0 0 0 0 0 TOIE1 Timer Counter Overflow Interrupt Enable timer Counter 1 If this bit is set with an overflow of the data pointer timer Counter a timer OVERFLOW 1 interrupt is released Global the Enable interrupt flag must be naturally also set TIMSK OCIE1IA Output Compare Match Interrupt Enable timer Counter 1 TIFR With the timer Counter 1 additionally a reference value can be defined to the overflow If this bit is set with reaching the reference value a Compare match interrupt 1s released Global the Enable interrupt flag must be naturally also set TICIE Timer Counter Input Capture Interrupt Enable If this bit is set a Capture Event interrupt is released if an appropriate signal event at the pin PD6 ICP arises Global the Enable interrupt flag must be naturally also set even if an appropriate interrupt is to be released TOIEO Timer Counter Overflow Interrupt Enable Timer Counter 0 If
68. es define EFUSE atribute Section etuses select ext crystal 3 8Mhz unsigned char lfuse LFUSE lt lt CD iss rl ECC Ut lt lt ChSE ls E ih in O lt lt Ch Sri Sli ia ChSE EO lO lt lt cU TRI a Uro unsigned char hfuse HFUSE ARID YIN SVAN OR SPENS T e anD TON M BODCEVEL 25 IEC BNE VELI 9 0 KOIDE VAIO I ILI IDE Sieh 9 unsigned char efuse EFUSE MO S ELTEPRCENNI NOTE The bit locations were not completely tested A 1 means here that the Fuse bit is not programmed the function thus is in general not activated 0 however activate most functions This is as in the data sheet 1 unprogrammed 0 programmed The Makefile must be extended now still by the following targets with tabulator to engage not with blanks lfuses build OBJCOPY j lfuses change section address lfuses 0 O ihex S TARGET elf S TARGET lfuse hex Git amp S TARGET ltuse hex then S AVRDUDE S AVRDUDE_FLAGS U lfuse w S TARGET lfuse hex deadly hfuses build OBJCOPY J hfuses change section address hfuses 0 O ihex S TARGET elf S TARGET hfuse hex ise eS ANGIE arae lave 2 cleveran S AVRDUDE S AVRDUDE EFELACS U htuse w s TARGEI miuse hex fea efuses build OBJCOPY j efuses change section address efuses 0 O ihex S TARGET elf S TARGET efuse hex if f S TARGET efuse hex then S AVRDUDE
69. es don t put the header files at here INCLUDE files only lt c are to be assigned by blanks separately with SRC variable The file defined with TARGET is already contained in the SRC list Do not delete this entry SRC E TARCE Te Uare ne Ved ce lare Alternatively one can extend the list of the source coding files also with the operator SRC os TARGET a e n 7 heDNeCOde enor mene comecollenr lt 72s Ollie eonmmnetiatea 7 ONC lec ow c Te LCDMeOCer rom Sree nGoreeMluernocomenoller used oh Cs E Programming device adjust The collecting mains are adapted on the programming software AVRDUDE however also different programming software can be merged if this can be steered over command line e g stk500 exe uisp sp12 atti ude for Siko00 on comli oul commentated of AVRDUDE_PROGRAMMER stk50O0O com serial port Use Iptl to connect to parallel port AVRDUDE PORT coml programmer connected to serial device OF H e attitude for STK200 Dongle on prel AVRDUDE_PROGRAMMER stk200 AVRDUDE_PORT lptl If Flash hex and EEPROM eep are to be programmed together on the microcontrollers the comment symbol is to be deleted forwards AVRDUDE_ WRITE EEPROM out commentates EERPOM contents not written AVRDUDE_ WRITE EEPROM U EEPROM w TARGET eep does not out commentate EERPOM contents written AVRDUDE_WRITE_EEPROM U EEPROM w TARGET eep Application The provided Makefi
70. experience one can however on own danger and naturally not for standard sets small little far fallings with the ATMEGAS8L taken by me under the magnifying glass thus the Low Voltage variant quite still functions the ADC with 5V operating voltage with up to VREF 1 15V down correctly starting from 1 1V and among them digitizes he however only Bl dsinn I would go for safety s sake not under 1 5V and with lower operating voltages like itself the lower bound for VREF at the pin AREF if necessary upward shift In addition in the last revision of the data sheet it is corrected that ADC4 and ADCS very probably offer 10 bits accuracy and not only 8 bits as indicated in older revisions erroneously
71. gm_read_byte an indication could be read by the Flash which does not represent the stringer end character the read indication over the normal channels sends away Ue ia Sp e shinelioe eros 5 CEKU FIr Macros are defined by some libraries which automatically a PSTR inserts on use of a function A view into the header file of the library shows whether this is the case An example from P Fleury s LCD LIBRARY cutout from the header file lcd h the Fleury LCD Lib aE extern void lcd puts_p const char progmem_s rdefine lcd puts EP s Ted puts P PSOTR 3 a in an application wieauchimmmer c include lt avr io h gt include lt avr pgmspace h gt include lt string h gt finelude Lod n char StringImFlash PROGMEM Erwin Lindemann in the Flash ee tooa pako pP tring la n Topor Eee Ro par e from it becomes wg define Icd_put_P lcd_puts_p PSTR Dr Kloebner ee Flash in application write With AVRs with self programming option also admits as boat load he support parts of the Flash memory can be described also by the application program This is possible only if the write functions are put down in a special storage area boat section of the program memory Flash With few small AVRs there is no separate boot section with these can the Flashspeicher by each place of the program be written For details is here referred to the respective
72. h avrfreaks or in the Procyon avrlib e A further beginning does not require a pin with interrupt function however needs more computing time Each input pin can serve as receipt pin RX Over a timer the condition of the RX pin with one is scanned the multiples Baud rate three way seems usual and High and or Low bits identified on the basis a minimum number Example Gene Eric software Uart Application note of IAR Newer AVRs e g ATtiny26 or ATmega48 88 168 169 has universal a Serial interface USI which can take over partial UART function Atmel makes a Application note available in which the use of the USI is described as UART in principle hardware supported software UART e See also Resuming information inclusive examples of the use of stdio functions printf etc in the AVR Tutorial UART e Peter Fleurys UART Bibliotheca for avr gcc avr libc Analog input and output Analog input values are usually read in over the AVR analog digital converter AD transducer ADC which is available in many types typically 10bit dissolution Analog signals tensions are changed by this into digital numerical values With AVRs which have no internal AD transducer e g ATmegal62 ATtiny2313 can by external wiring R C network and time measurement the function of the AD transducer become emulated No AVRs with inserted digital analog converter DAC exists This function must be copied by external components
73. h the declaration variable in the EEPROM is to be supplemented the attribute for the section eeprom See in addition the following example include lt avr io h gt include lt avr eeprom h gt include lt avr interrupt h gt include lt inttypes h gt in current versions avr lib with xx h merged of the EEMEM with current versions avr lib in eeprom h defined here define if yet does not admit old avr libc ifndef EEMEM all passages in the text EEMEM in the source code through __attribute_ replace define EEMEM attribute __ section eeprom toodi aT 7 Byte 7 uint8_t eeFooByte EEMEM 123 jo Word 47 uintl6 _t eeFooWord EEMEM 12345 gt EO float eeFooFloat EEMEM Byte Field UlMES t CeroOobyecArrcayl FEMM Io 29 70 7 uint8_t eeFooByteArray2 EEMEM W J O GPe une ae shore T al 77 uintl6_t eeFooWordArrayl 4 EEMEM a ree With the tools belonging to the compiler can be written from the variable declaration derived EEPROM contents into a file usual file dung eep data in Intel the Hex format Makefiles after WinA VR MFile collecting main contain already the necessary parameters Contents of the eep file must be likewise transferred to the microcontroller Write EEPROM if the start up values from the declaration are expected by the program Otherwise the EEPROM memory contains after the transmission the Programmers by means
74. he AVR If it should be somewhat more exact then we must fall back to a AVR with inserted analogue digital converter ADC which has several channels It is called channels in this connection that up to ten analog inputs at the AVR are available but only more genuinely an analogue digital converter is available before the actual measurement is thus to be adjusted which channel pin is connected and measured with the transducer The transformation within the AVR is based on the gradual approximation With the AVR the pins AGND and AVCC must be wired For precise measurements AVCC should be connected by a L C network with VCC in order voltage peaks and break downs away from the analogue digital converter to keep In the data sheet in addition a circuit which and 100 plans 10 MicroHenry nF is The result of the analog digital transformation is referred to a reference tension Current AVRs offers three possibilities for the choice of this tension e An external reference tension of maximally Vcc at the connection port AREF The minimum external reference tension may be however not arbitrarily low see in addition most current the data sheet of the used microcontroller e Ifthe AVR has an internal reference tension this can be used All current AVRs with internal AD transducer should be equipped with it see data sheet 2 56V or 1 1V depending upon type The data sheet gives also over the accuracy information to this tension
75. he compiler translates these instructions for an ATmegal28 with optimization stage S after PORTA 1 lt lt PAO ely amp d8 9a sbi Oxia O53 27 sta PORTA 1 lt lt PAZ2 1 lt lt PA3 1 lt lt PA4 od slor IOS ag r247 Oz lD 2T D do eo cI OLL A E EE oe do 8b bb Out Oklo no ace Setting of the individual bit is translated during switched on optimization for registers in the lower storage area into only one assembler directive sbi and is not susceptible to Unterbrechnungen by interrupts The instruction for setting three bits 1s translated however into three dependent assembler directives and offers thereby two points of attack for Unterbrechnungen An interrupt routine could change the value of the register to the shop of the starting situation into the buffer here register 24 delete e g a bit Thus the buffer no more was not written back however nevertheless with the actual condition to agree after the bit operation here ori into the register Example PORTA is at the beginning of 0b00000000 The first instruction A sets bit 0 PORTA is thereafter 0b00000001 Now read in the first part of the second instruction the port condition into a register B Directly on it before C an interrupt fires in whose interrupt routine bit 0 is deleted by PORTA After leaving the interrupt routine PORTA has the value 0b00000000 In the two still following instructions of the main program now the buffered old
76. he respective interrupt event implement in the interrupt routines only All less critical tasks are then processed in the main program e see also Documentation avr libc the section Modules interrupt and of signal Memory accesses Atmel AVR microcontrollers have typically three memories e RAM In the RAM more exactly static RAM CRAM by the GCC compiler place for variables is reserved Also the stack is in the RAM This memory is volatile 1 e contents of the variables are lost with switching off or a collapse of voltage supply e Program memory Implemented as FLASH memory again record ably by page In it the application program is put down e EEPROM Non volatile memory 1 e once written contents remain also without current supply Byte by byte write readably In the EEPROM typically device specific values are e g put down like calibration values of sensors Some AVRs do not only possess a RAM memory the registers can as work variables be used Since the application of the avr GCC to such small control learn is anyway rarely meaningful and also only with some RAM lots types after amateur handicrafts is possible these microcontrollers are not continued to consider here Also EEPROM memory is not available on all types Generally the following explanations should be transferable to all ATmega microcontrollers and the larger AT90 Typen To the types ATtiny2313 and ATtiny26 of the tiny row apply the remarks l
77. hereby as on off counter which counts from 0 to upward up to the upper limit and afterwards again back on 0 The upper limit results from it whether 8 9 or 10 bit PWM is used in accordance with the following table Dissolution Upper limit Frequency 8 255 frc 510 9 S11 frc 1022 10 1023 frc 2046 If now the counter value in the data pointer achieves the value stored in OCR1H OCRIL the expenditure pin OC1 is set and or reset depending upon attitude of COM1A1 and COM1A0 in the TCCR1A Register I tried to summarize the appropriate signals in the following diagram Inverted Piti 57575775 oe wepuennwmnbeaes Ceoariter a Pitty Signal Pulse Width Reference value examination Here into a special reference value register OQCR1IH OCRIL a value is written which is constantly compared with the current counter value If the counter achieves the value registered in this register then a signal 0 or 1 at the pin OC1 can be produced and or an interrupt be released Catch an input signal inputs Capturing With this mode of operation at the inputs Capturing pin ICP of the microcontroller a signal source is attached Now knows depending upon configuration either a signal change from 0 to 1 rising flank or from 1 to 0 falling flank to be recognized and at this time current count into a special register be put down At the same time also an appropriate interrupt can be released If the signal source contains a strong noise the int
78. ided and was already adapted for ATmegal6 microcontroller One can work on and adapt the Makefile to other microcontrollers or together click oneself with the program Mfile which is contained in WinA VR Distribution a Makefile menu controlled mitile E mE File Makefile Help He sed H fi Code generation f Anaa Hir ain fle nahe ric B Weddington drg Wunech et al H M h Ael MCU type d H Output Format ET aa Optimization level p written by H Tim Debug format H Coll C standard level HRe cic 4 source filets H blai tt Sap Assembler source Filefsi H Fre printti options Lar scant options H External RAM options EO Aypdide mal Programmer H Port H mal H Miscellaneous mat Enable Editing of Makefile s lt gt The Makefile is saved under the name Makefile without extension 1 e EXE for example in the same folder into also the file main c the program code is put down More detailed explanations for the function of Makefiles are in the following to section Exploring Makefiles D tmp gec_tut gquickstart gt dir quick start of D tmp gcec_tut gquickstart Zoek 2006 22 53 lt DIR gt Loa dL Le 2006 22753 lt DIR gt i 28 11 2006 20 06 118 main c 20 dlt 2006 20 03 16 810 Makefile 2 files en 16 928 Bytes Now one enters make all If the Programmers Notepad installed with WinAVR is used there is in addition a Menu option in the Tools menu If all parameter
79. ikewise RAM The administration of the RAM memory affected via the compiler as a rule is not to be considered with the access to variables in the RAM anything special The explanations in each useful C book apply also to the code produced by the avr GCC compiler Program memory Flash An access to constants in the program memory is not possible by means of avr GCC transparency I e there are necessary special access functions in order to read data from this memory In principle all access functions are based on the assembler directive Ipm load program MEMORY The standard run time library of the avr GCC avr libc makes these functions available after merging the header file pgmspace h With these functions individual bytes data items know 16bit and data blocks to be read Declarations of variables in the Flash memory are supplemented by the attribute PROGMEM Local one variable actually constants within functions can be likewise put down in the program memory In addition is to be placed in front with the definition however static since such variables cannot be administered on the stack and or during optimization in registers The compiler throws a warning if static is missing include lt avr io h gt include lt avr pgmspace h gt include lt inttypes h gt ae Byte 4 7 Conot ulnto i PpomPoobytee PROGMEM TIZ E a 7 const uintl6_t pgomFooWord PROGMEM 12345 Byte Field const uint8_
80. ile When you found yourself in trouble DO THIS e Find out whether it s actually an avr GCC specific problem or you just requires the revitalization of your C knowledge One knows possibly general C questions Otherwise read gibt s free of charge on line C book e AVR check list e Above all The avr libc documentation however not only the section Related Pages Frequently Asked Questions questions often posted and answers in addition e The article AVR GCC in this Wiki read e The GCC forum on www mikrocontroller net after comparable problems search e The avr GCC forum with avrfreaks after comparable problems search e Archives of the avr GCC mailing list after comparable problems search e Look for example code Particularly in the Academy of AVRFREAKS announce e Google or yahoos ask never harm e For problems with the control of internal AVR functions with C code read the data sheet of the microcontroller completely and at the best one twice Data sheets are available by the Atmel web pages as pdf files The complete data sheet complete and not the edited version summary use e In addition the example programs in the AVR Tutorial are written in AVR assembler explanations and proceeding are transferable to C programs e A contribution into one of the forums or write a Mail to the mailing list Give as much as possible information microcontroller compiler version used libraries cu
81. in all mouth but many users understand not completely how PWM actually functions As we know all a microcontroller is a purely digital construction unit If we define a pin as output then we can set this output either on HIGH on which against the output supply voltage Vcc rests or however we set the output on LOW according to which then OV is because of the output What happens however now if we switch periodically with a firm frequency between HIGH and LOW Correct we receive a square wave voltage as the following illustration shows pulse Wradth Penod Frequenz This square wave voltage has now a geometrical average value which is depending upon Pulse width smaller or larger Penod Frequenz If we filter now this pulsating output voltage still over an RC element smooth then have we already appropriate DC voltage produced With the AVRs we can produce directly PWM signals In addition the 16 Bit serves counter which can be operated in the so called PWM mode Note In the following considerations as microcontroller of the 90S2313 one presupposes The theory is comparable with other AVR Controller the pin allocation however not necessarily why a view is urgently recommended in the appropriate data sheet In order to activate the PWM mode control register A TCCRIA the pulse width modulator bits PWM10 and or PWM11 must be set according to following table in the timer Counter1 PWM11 PWM10 Meaning 0 0 P
82. ineffective The delivery of a pointer would be the solution if the compiler would not optimize Because one reads thus in the program not by the hardware but again only by an image in the memory The result would be the same as above With the keyword volatile one says now to the compiler that the appropriate variable can be changed either by other software routines interrupts or by the hardware In all other respects volatile characterized variables can be defined also as const in order to guarantee with that they are alterable by the hardware only The UART General to the UART By the UART an AVR can be connected easily with a RS 232 Schnittstelle PC or other devices with serial interface Possible applications of the UART e Debug interface e g to the announcement of intermediate results printf debugging here better UART debugging on a PC On the computer in addition a terminal software Ms Windows is enough HyperTerminal or better Bray terminal HTerm Unix Linux e g minicom A direct connection is not possible due to different levels however appropriate interface ICs is as to be integrated e g a MAX232 favorably and easy Computers without serial interface can be attached over finished USB serial adapters e Man machine interface e g configuration and status inquiry over a command line or menu e Transferred by stored values e g with a Data logger e Connection of devices with serial interf
83. ion determines 11 1 1 whole ones of port o 11 2_pre defined bit numbers for I O registers o 11 3 digital signals o 11 4 outputs o 11 5 inputs as signals come into uC 11 5 1 signal coupling 11 5 2 keys and switches 11 5 2 1 activation of pull up resistors 11 5 2 2Debouncing inputs o 11 6analog o 11 7 16 Bit port register ADC ICR1 OCR1 TCNT1 UBRR o 11 8 IO registers as parameters and variables e 12 the UART o 12 1 general to the UART o 12 2 the hardware o 12 3 sending with the UART 12 3 1_sending individual indications 12 3 2 Writes of a character string stringer 12 3 3 Writes of variables contents o 12 4 indications receiving o 12 5 software UART 13_analog input and output o 13 1 ADC Analog to digital converter 13 1 1 the internal ADC in the AVR 13 1 1 1 the registers of the ADC 13 1 1 2_activating the ADC 13 1 2 analog digital transformation without internal ADC 3 1 2 1 fairs of a resistance 13 1 2 2 ADC over comparator o 13 2 DAC digital analog to converter 13 2 1 DAC over several digital outputs 13 2 2 PWM pulse width modulation 14 the timers Counter of the AVR o 14 1 the prescaler o 14 2 8 bits timers Counter o 14 3 16 Bit timer Counter 14 3 1 the PWM mode of operation 14 3 2 reference value examination 14 3 3 catching an input signal input Capturing o 14 4 common registers 15 Sleep modes 16 the Watchdog o 16 1 How now does the Watchdog function o 16 2 Watchdog Possi
84. isting points out also the priority of the interrupts e RESET e External interrupt 0 e External interrupt 1 e Timer Counter 1 Capture event e Timer Counter 1 Compare match e Timer Counter 1 overflow e Timer Counter 0 overflow e UART indication receive e UART data pointer empty e UART indication sent e Analog comparator The number of possible sources of interrupt varies between the different types In the doubt a view helps in the data sheet interrupt Vectors Register At90S2313 had 2 registers with the interrupts together hang General Interrupt Mask Register Bit 7 6 5432 1 0 Name INT1 INTO R W R W R W RRRRRER Initial value 0 0 0 00 0 0 0 GIMSK INT 1 External Interrupt Request 1 Enable If this bit is set an interrupt is released if by the INT1 Pin a rising or falling depending upon configuration in the MCUCR flank is recognized Global the Enable interrupt flag must be naturally also set The interrupt is also released if the pin is switched as output In this way the possibility is offered of realizing software interrupts GIFR MCUCR INTO External Interrupt Request 0 Enable If this bit is set an interrupt is released if by the INTO Pin a rising or falling depending upon configuration in the MCUCR flank is recognized Global the Enable interrupt flag must be naturally also set The interrupt is also released if the pin is switched as output In this way the possibility
85. ivecommons org licenses by sa 2 0 Providing that NOT to make any Edits in the first three pages of this Document without direct permission from me You can contact me at the following E mail Takashi85eg gmail com Please make the message title AVR GCC Tutorial or it may be moved to SPAM Contributors in the translation Hello Is any body here If you think you deserve to be mentioned here go ahead and write your name and make me know at Takashi85eg gmail com The document still needs more work to reach its final version Table of contents l preface 2 needed tools 3When you found yourself in trouble DO THIS 4 Generating the machine code 5 introduction example 6 Exploring Makefiles o 6 1 type of microcontroller set o 6 2 source coding files register o 6 3 programming device adjust o 6 4 application o 6 5 other parameters 6 5 1 optimization degrees 6 5 2 Debug format 6 5 3 assembler files 6 5 4 clock frequency o 6 6 input files for simulation in AVR Studio 7 integral ones Integer data types 8 bit fields 9 fundamental program structure of a uC program o 9 1 sequential program sequence o 9 2 interrupt controlled program sequence 10 general accesses to registers o 10 1 I O registers 10 1 1 Read ofa I O register 10 1 1 1_ Read of a bit 10 1 2 write of a I O register 10 1 2 1l write of bits 10 1 3 control rooms on a certain condition e 11 access to port o 11 1 data direct
86. l timers and or counters 0 8 bit PWM mode of operation activated 0 l 9 Bit PWM mode of operation activated l 10 bit PWM mode of operation activated 0 0 Timer Counter Control Register B timer 1 Bit 7 6 5 4 3 2 l 0 Name ICNC1 ICES1 CTC1 CS12 CS11 CS10 R W R W RW RR R W R W RW RW Initial value 0 0 0 0 0 0 0 0 ICNC1 Input Capture Noise Canceler 4 CKs Timers Counter 1 or on German intercarrier noise suppressor of the input signal If this bit is set and with the input Capture signal is worked after triggering the signal with the appropriate flank rising or falling at the input Capture pin ICP in each case 4 measurements with the CCU frequency of the input signal is in such a way queried Then only if all 4 measurements exhibit the same condition apply the signal as recognized ICES1 Input Capture Edge Select Timer Counter 1 With this bit it is determined whether the rising ICES1 1 or falling ICES1 0 flank is near drawn for the evaluation of the input Capture of signal on pin ICP CTC1 Clears Timer Counter on Compare match Timer Counter 1 If this bit is set then after an agreement of the data pointer TCNT1H TCNTI1L with the reference value in OCR1H OCRIL the data pointer TCNT1H TCNTIL is set to 0 Since the agreement because of the clock is treated according to the comparison a something else results counting behavior depending upon adjusted prescaler If the prescaler is set to 1 and C is the respective
87. late it again and voila this time it does have a meaning Google actually helped me correcting the Germans misspellings I corrected amp translated dozens of words by this method I guess that I have learned much Germany in those three weeks of this tutorial debugging three weeks is not from the salt amp sugar At last guess what I did the job for the project in assembly not because the tutorial is bad but because this document debugging consumed all the time amp effort And assembly which I am familiar with seemed to be a quick practical solution more than debugging the document amp printing it I have learned that at some times it s easier to select the hard ways than following what the others tell you that it s the easiest ways THE END At last I decided to share this work with the AVR English speaking community Iam not clamming it s a perfect translation I do not speak Germany remember But in the hope that the internet community would help proofing this document against spelling amp grammar mistakes that is still resident amp OF COURSE TRANSLATE THE HEADSTRONG WORDS THAT neither GOOGLE NOR ME COULD TRANSLATE IT I hope to see the beta version soon http www bridgetofaith com License You can freely distribute and make enhancements to the technical related parts of this document and its next versions under the creative commons share alike 2 0 license to be found at the following URL http creat
88. le and the code must be in the same file also the file name should not be changed The input of make all in the work dierctory with the Makefile and the source coding files produces among other things the files superprog hex and superprog eep Dependence between the individual C files are considered automatically thereby Superprog hex and superprog eep with make are transferred program to the microcontroller With make clean are deleted all temporary files cleared up Other parameters Optimization degree The GCC compiler knows different stages of the optimization Only to test purposes the optimization should be deactivated completely OPT 0 The further possible options instruct the compiler to produce as compact or as fast a code as possible Into that most cases OPT s is by far the optimal sic attitude thus more compactly and often also the fastest machine code is produced Debug format The formats of stabs and dwarf 2 are supported The format is stopped behind DEBUG See in addition section input files for simulation Assembler files The assembler files used in the project are separately listed behind ASRC by blanks Assembler files have always the ending S large S For example the assembler source code of a software UARTs is in a file softuart S contained reads the line ASRC softuart S Clock frequency Newer versions of the WinAVR Mfile collecting main for Makefiles contain the definition of a v
89. lize the UART first times In addition we set the necessary bits in the UART control register depending upon desired function mode Since we would like to send only and want still no interrupts to evaluate for the time being turn out the initialization really very simply since we only the Enable bit transmitters must set UCR SNI TTEN Newer AVRs with USART s has several configuration registers and to require something other configuration For a ATmegal6 e g U PETE EE ART eye UCSRC A UR SHIN ING TeS r aN Now is still that and or is still the Baud rate registers to adjust UBRR and or UBRRL UBRRH The value for it results from the indicated formula from using the clock frequency and the desired data transmission rate One knows the calculation of the formula the Preprocessor directives left fo URE TNE Pot create oOSGe ols 7 ifndef F CPU in newer version of the WinAVR Mfile Makefile collecting main can be defined F_CPU in the Makefile a repeated definition to a compiler warning Will lead here Therefore protection through ifndef endif for example 4 MHz Quartz if not already in the Makefile defines define F_CPU 4000000 endif define UART_BAUD_RATE 9600 9600 Baud die Meru AO Il WER CPU 7 UAB EAU eins Ibi is ap RE Again for the Megal6 with a 1 6bit Register something other programming USART blank INIT with the ATmegal6 ifndef F CPU define F_CPU 3686400 OSa Cor L
90. ls available which have integrated hardware a UART and or a USART The names of the registers are defined in the header files to the appropriate AVR types If in the Makefile the MCU type is defined by the system to types fitting definition file is used automatically as soon as one merges the general io h header file in the code include lt avr io h gt If the MCU type is defined e g with the contents of atmega8 in the Makefile when reading the 1o h file in implicitly automatically also the 1om8 h file with the register definitions for the ATmega 8 is read in I O register The I O registers have a special value with the AVR control learn They serve the access to Port and the interfaces of the microcontroller We differentiate between 8 bits and 16 Bit registers For the time being we treat times the 8 bits registers Each AVR implements a different quantity of GPIO registers GPIO General Purpose Input Output The following examples proceed from an AVR which possesses both Port A and Port B Accordingly they must be adapted for other AVRs for example ATmega8 48 88 168 Read an I O register For reading one can access I O registers simply as a variable In source codes which were developed for older versions of the avr GCC avr libc the read access 1s made by the function inp Current versions of the compiler enables the access now directly and inp are no longer necessary Example tinclude lt avr Iio
91. mel add ons directly by the compiler Proceeding with dwarf 2 e inthe Makefile with DEBUG DEBUG dwarf 2 e make all possibly before make clean e the produced e f file in the example above superprog elf into AVR Studio load e AVR simulator and to simulating microcontrollers select finish e further see AVR Studio on line assistance Proceeding with extcoff Should be only used in exceptional cases e inthe Makefile with DEBUG DEBUG stabs e make extcoff possibly before make clean e the produced cof file in the example above superprog cof into AVR Studio load e AVR simulator and to simulating microcontrollers select finish e further see AVR Studio on line assistance When simulating often variables seem to be missing A cause for it is that the compiler assigns the variables directly to registers This can be avoided as the optimization is switched off in Makefile One simulated then however a program deviating strongly from the optimized code Switching the optimization off is not recommended Instead of the software simulator the AVR Studio can be also used in order to debug with the ATMEL JTAGICE a reproduction of it Boot ICE Evertool or the ATMEL JTAGICE MKII in system In addition no special parameters are necessary in Makefile Debugging and or in system emulation with the JTAGICE and JTAGICE MKII is described in the AVR Studio on line assistance The use of Mak
92. nother variable from a old version define EEPROM DEF OxFF uint o sew rOoObyGebDemal i tu 277 if myByte eeprom_read_byte amp eeFooByte EEPROM_DEF myByte fooByteDefault Word read write Letter and reading from data items take place similarly to the proceeding with bytes ee Uliano E Wi Aoucels myWord eeprom_read_word amp eeFooWord read myWord have now the value 12345 Vl ee myWord 2222 eeprom_write_word amp eeFooWord myWord write re Block read write Vintages and letters from data blocks is made by the functions eeprom_read_block and or eeprom_write_block The functions expect three parameters the address of the pouring and or target data in the RAM EEPROM ADDR eats and the length of the data block in bytes size_t TODO Caution the following examples are not yet examined first times only as reference to the principle Possibly are missing casts and possibly still more A ee uinco t myby eBufier uintl6_t myWordBuffer 4 data block from EEPROM VINTAGES reads 3 bytes however the EEPROM address defined by eeFooByteArrayl into the RAM array more myByteBuffer eeprom_read_block myByteBuffer eeFooByteArrayl 3 meaning somewhat more descriptive however useless tapping work eeprom_read_block amp myByteBuffer 0 amp eeFooByteArray 0 3 meaning with something security the length concerned eeprom_read_block myByt
93. number of the port indexing the bits 0 2 If the register is described while that a transformation runs and then first the current transformation on the past channel is terminated This is to be considered particularly with the freely running enterprise A recommendation is therefore this that the freely running enterprise should be used only with an individual analogue input which can be used if one wants to save problems with the Change over switch Activate the ADC In order to activate the ADC we must set the ADEN bit in the ADCSR register In the same step we specify also equal the mode of operation A small example of the single conversion mode with a ATmegal69 and a use of the internal reference tension with 169 1 1V with other AVRs also the 2 56V I e the input signal may not exceed if necessary with voltage dividers stop this tension Result of the routine is the ADC value thus 0 for 0 Volt and 1023 for V_ref Volt uintl6 t ReadChannel uint8 t mux Unione e aL uintl 6 _t result 0 Initialization importantly since local variables not are initialized automatically and coincidental values to have Otherwise knows rubbish get a LONG ADCSRA 1 lt lt ADEN 1 lt lt ADPS1 1 lt lt ADPSO frequency prescaler Ve SeenON ml wate ADC 2CEiy 4 ae ADMUX mux channel select ADMUX 1 lt lt REFS1 1 lt lt REFSO internal reference tension use after activating the ADC
94. of ISP on the attitude of the EESAVE Fuse see data sheet section Fuse bit the previous data EESAVE programmed 0 their position possibly no longer with the allocation in the current program agrees dependent or the default value after chip Erase OxFF EESAVE unprogrammed 1 As safety device one can reproach during the reading for OxFF examine the default values new in the program and use a default value if necessary Bytes read write Avr libc the function for reading a byte is called eeprom read byte Parameter is the address of the byte in the EEPROM Over the function eeprom write byte with the parameters address and contents are written Example of use V7 tle uint8_t myByte myByte eeprom_read_byte amp eeFooByte read myByte have now the value 123 ee myByte 99 eeprom_write_byte amp eeFooByte myByte write Vee myByte eeprom_read_byte amp eeFooByteArrayl 1 myByte has now the value 3 ee example for the safety device newst empty EEPROM after chip Erase e g if the eep file after programming of a new version of the program is not into the EEPROM it became necessary to transfer it and EESAVE is deactivated unprogrammed 1 A caution if EESAVE is programmed this safety device does not continue to help since the memory address meals in a new extended program Then amp eeFooByte were possibly shifted in its place stands possibly the value of a
95. of the CCU clock count let now the Timer0 into operation we write the following command line ECE OM ik lt C S00 es5 07 The counter counts now upward to 255 in order to then begin again with 0 The current count stands in TCNTO With each overflow of 255 to 0 timer is set the OVERFLOW flag TOVO in the timer interrupt flag TIFR register and released if configures in such a way an appropriate timer OVERFLOW interrupt and processed the interrupt routine bound to it The TOV flag leaves itself by writing a 1 and not as expects 0 again to put back 16 Bit timer Counter Many AVR models possess 16 Bit timer except the 8 bits timers also The 16 Bit timer Counter is somewhat more complex developed more possibilities than the 8 bits timers Counter offers for it in addition many than are there e The PWM mode of operation production of a pulse far modulated output signal e Reference value examination with production of an output signal output Compare match e Catch an input signal with storage of the current counter value input Capturing with insertable intercarrier noise suppressor Noise Filtering The following registers are assigned to the timer Counter 1 Timer Counter Control Register A Timer 1 In this and the following register we adjust as we would like to use the timer Counter The register is developed as follows Bit 7 6 5143 12 1 0 Name COMIA1 COMI1A0 PWM11 PWM10 R W R W R W RR RR RW R W Initial value
96. ons that of status register with the bit UDRE depends on microcontroller types see data sheet V7 When TAVR Witte a VART classic AVR ecg Aro0Ses1 5 while USR amp 1 lt lt UDRE waits for possible sending UDE see Slew i Molenn tl On wit tees 6 oe PRE OR E A with newer AVRs stands the status in UCSRA UCSROA UCSRIA here e g for ATmegal 6 while UCSRA amp 1 lt lt UDRE waits for possible sending UDR x ERA ie me een a a S O e inte ais eon Write to a character string stringer The task stringer send by two functions one processes The universal microcontroller independent function uart puts hands in each case an indication to the character string over to a function uart_putc which must be implemented dependent on the existing hardware In the function for sending an indication is to be made certain that before sending it is examined whether the UART is ready the transmission job to receive pute for AVR with a VART e g AT90S8515 IoC Garl PU el UmswWoned Citar C SoLL US Re I UDR Welty CO R eae 7 UDR C Send GO Indra tions 7 return OF with newer AVRs other name for the status registers here ATmegal Ine Uart PUC UiaS Nome cl CNar o while UCSRA amp 1 lt lt UDRE waits for possible sending UDR C Loena O Inda CaL Oe 7 Tecuo oO PUTS is independently of the type of microc
97. ontroller vord Wath Puro Rar e while s PATSO bong sl S 0 Goes uncegually Ne seringe end character 7 Gre a ON Sit Waiting loops are to that extent somewhat critical since during sending a stringer no more will not react to other events can The use of FIFO first in first out is more universal buffers in which and or the received indications byte buffered and by means of interrupt routines at the U S KIND which can be sent are passed on and or selected In addition finished components libraries Libraries exist which one can integrate quite simply into own developments It is advisable to use these components and not to invent the wheel again Write of variables contents If contents of variable integers floating point in more human being readably form are to be sent a transformation is necessary in indication ASCII before the transfer With only one number this transformation is relatively simple one adds the ASCII value from zero to the number and can this value directly send Ve are 74 here uart pure S20 expenditure of 0123456789 leis er for Wine 6 e 10 I oe Fr Caa a 0 uae EU CE R SPOT C enS e puree 1 O If more than one number is to be spent one avails oneself of appropriately existing functions for the transformation of numbers in character strings stringers The function avr libc for the transformation of signed 16bit Ganzzahlen int16 t in character strings
98. ourse S int main Count r o Uac pu a te Counter l Bare OU aa Ze A further elegant possibility is offered of bending the expenditure stdout on own functions tinc ude odio i Lat Gare pU Aar eaor e FIE serean skace PILE mye dout FPE OFRIO TREAN uart ue har NULL eee Diao OUI ANRT TES I Ine Gare Poe Nar enar e FELE r an ven Vn i art eureham i TArt otr an loop uni lipi is eet C UC Sry as UDG ODE Cs return O int main void TaLe Gari ee stdout amp mystdout Pier TH le wer lc Vn reorua o Jj oUr e a e e ana 4 aa oa 7 If floating point numbers are to be spent another larger version must be merged printflib in the Makefile The disadvantage of all printf variants They are quite memory intensive Assembler and Inline assembler Occasionally it proves as useful to use C and assembler code in an application Typically the main program in C is written and few extremely time critical or hardware near operations in assembler The gnu Toolchain offers for it two possibilities e Inline assembler The assembler directives are integrated directly into the C code A source coding file contains thus C and assembler directives e Assembler files The assembler code is in own source coding files These are assembled by the gnu assembler avr as to Object files compiles and with the Object files provided from the C code tied together linked
99. piler supports this without this detour The designation is the functions only for registers with addresses in the lower storage area into the assembler directives cbi and sbi to be actually translated anyway misleading there a sbi PORIE PB2 CHINPORI CA POI new also not more really new POREB iar Boy PORTC 6 amp lt lt P Cl Wants or if one cannot portieren the code the header file 1s to be merged compat deprecated h for the further use of sbi and cbi Who wants absolutely can naturally own macros with more meaningful names define itself For example define SET_BIT PORT BITNUM PORT 1 BITTNUM I define CLEAR_BIT PORT BITNUM PORD S 1 BITNU define TOOGLE_BIT PORT BLITNUM PORT ns E B TENUM I Self defined non standardized integral data types With in the following the type definitions mentioned it is to be noted that the names for words are partly used depending upon processor platform differently The indicated definitions refer to the bit widths usual in connection with AVR 8 bit Microcontrollern in explanations concerning the ARM7TDMI often 32 bit Integer with word are e g designated without further addition It is advisable to use during the revision of old code the integral data types standardized in the section described data types stdint h and prevent thus misunderstandings which can occur e g with the Portierung of C code between different platforms
100. place then SO Uine sie templ Uline le c temp Templ eeercm weac lots ee valve e Se omom Sac wore eS wowc dll Whether in avr libc the existing functions for it can be used I do not know But in some cases one must build oneself anyway own functions which the specific requirements interrupts atom problem etc to fulfill The possibility described above is only one possibility how one can realize this It offers a relatively simple kind the EEPROM values in arbitrary addresses to put or addresses change The other possibility consists of occupying the EEPROM values as follows VU TIO a a file eeprom c their own project VL ITD I I I ae include eeprom h own EEPROM header file merge uint8 t ee mem EESIZE EEMEM 0x00 ee dummy 00n ee a e OxOl1 ee _wordiL 0x00 fe E a a OxFF V Cen Value I Here one knows variables which are larger than more simply define 1 byte and one must define only the Highbyte or Lowbyte address in eeprom h However one must watch out here h llisch that one slips one or more positions not around Which of the two possibilities one begins it depends above all on the fact how many byte Word and other variable one use To accustom one should be able oneself to both variants Small concluding remark e The avr GCC supports the variant 1 and the variant 2 e Icc avr the compiler supports only the variant 2 Admitted problems with the EEPROM func
101. r A In this register we adjust as we would like to use the ADC The register is developed as follows 0 l 2 3 4 5 6 7 Bit ADPS0 ADPS1 ADPS2 ADIE ADIF ADATE ADSC ADEN Name W R R W R W RW R W RW RW R W 0 l 0 0 0 0 0 0 Initial value ADEN ADC Enable This bit must be set in order to activate the ADC at all If the bit is not set the pins can be used like normal I O pins ADSC ADC start Conversion With this bit a measuring procedure is started In the freely running mode of operation the bit must be set in order to activate the continuous measurement If the bit is for the first time set after setting the ADEN bit the microcontroller implements first an additional transformation and only then the actual transformation This additional transformation is accomplished for initialization purposes The bit remains now so long on 1 until the transformation is final in the case of initialization to the second transformation took place accordingly and goes to it on 0 ADATE ADC Ato trigger Enable With this bit the mode of operation 1s stopped A logic activates the ADC with a trip trigger adjusted in the SFIOR register If no bits are written in the SFIOR register the ADC in the freely running mode works The ADC now constantly measures the selected channel and writes the measured value into the ADC DATA registers ADIF ADC interrupt flag This bit is set by the ADC if a transformation taken place and the ADC DA
102. r interface it s however along installed with WinAVR amp however as TCL TK program which is executable on almost all platforms The following remarks refer to the WinAVR example Makefile There are three parameters in the Makefile which are handed over the shell and or the Windows command prompt cmd exe command com as parameters to make The program make looks for itself automatically the Makefile in the current work dierctory and accomplishes the operations for the appropriate call parameter defined therein Generates from the source codes a hex file and if necessary also eep file indicated in the ORELI Makefile make program The hex file and alternatively also the eep file for the EEPROM transferred to the AVR make clean all temporary files thus also the hex file are deleted These calls can be merged into the very most editors in Tool menus This saves the contact with the command line With WinAVR are already in the Tools menu of the provided editor Programmers Notepad inserted calls Usually the following data in the Makefile are to be adapted e Type ofmicrocontroller e Source coding files C files e Type and connection of the programming device Rarer the following parameters are to be accomplished e Degree of the optimization e Method for the production of the Debug symbols Debug format e Assembler source coding files S files The Makefile cutouts shown in the following subsections are for
103. rdingly to be supplemented Program the device program TARGET hex TARGET eep without Fuse Lock parameters after WinAVR collecting main conditions 4 2006 S AVRDUDE S AVRDUDE_FLAGS S AVRDUDE_WRITE_FLASH S AVRDUDE_WRITE_EEPROM with Fuse Lock parameters S AVRDUDE AVRDUDE_FLAGS AVRDUDE_WRITE_LFUSE S AVRDUDE_WRITE_HFUSE AVRDUDE_WRITE_FLASH S AVRDUDE_WRITE_EEPROM S AVRDUDE_WRITE_LOCK Far possibility consists of letting the Fuse and LOCK bit parameters of the pre processor compiler generate The Fuse bits are then written when using AVRDUDE into own Hex files For this one can use the e g following Construct Into one the C Source is defined a variable for each Fuse byte of the type unsigned char and packed into extra a section This can be passed either in an existing file or be written into a new e g fuses c The file must be compiled and linked in the Makefile however in any case with tiny 2313 fuses low byte define CKDIV8 7 define CKOUT 6 define SUT1 5 define SUTO 4 define CKSEL3 3 Ol time COSI 2 define CKSELI 1 derine F ELO 0 tiny2313 fuses high byte define DWEN 7 rder rne ERO AVE Aer T EN define WDTON define BODLEVELZ define BODLEVELL define BODLEVELO define RSTDISBL I GO ms GC OF tiny2313 fuses extended byte define SELFPRGEN 0 define LFUSE _ J eabEriIbDUre Atsection Liuses define HFUSE Jere ecibure sect aon htus
104. re are functions which wait in the library even until a certain condition on a bit is reached It is however normally a rather unpleasant programming techniques since in these functions becomes blocking waited That is called the program sequence stops here until the masked event took place If one uses the Watchdog one must make certain that this is also still triggered to put back the Watchdog timers The function loop_until_bit_is_set waits in a loop until the defined bit is set If the bit is already set with the call of the function the function is again left immediately The least significant bit has the bit number 0 a naclude lt ayr alone N gt A SCOMERO Tr OOM CODIE NO ehee r O e an reg ster RINAT IDE define WaitingPin PINA define WaitingBit PA2 Vy wich ave Libe tche function Le Sets locpnuntal on EARN WARTEBIT meaning in C standara goes through empties the loop the WAITING BIT in register waiting Pin LAA F NOT DOvVe ve sO Onn 0 4 ELC OI Nis NObsequal Marlenna Naena nae Ne lt lt iclaliesli iejealic as ar The function loop_until_bit_is_clear waits in a loop until the defined bit 1s deleted If the bit is already deleted with the call of the function the function is again left immediately The least significant bit has the bit number 0 Hl MekuGe lt avr Lo hi gt OnE TOL Er O EOT bi ENOT EE e a bat a E RRINE O define WaitingPin PINB define WaitingBit PB4 i avr li
105. rection on output place From it the succession input results gt set PORTx internal Pull UP actively gt set DDRx Output high With the order only DDRx and PORTx can come it to a short low pulse the also exterene of Pull UP resistors outvoted Unfavorable the succession Input gt set DDRx Output on low there PORT after RESET 0 gt set PORTx Output on high Comparisons to it also the data sheet section Configuring the pin Inputs as signals come into uC The digital input signals can arrive at different kinds at our logic Signal coupling It is simplest if the signals can be taken over directly from another digital circuit The output of the appropriate circuit TTL level knew then we even directly the output of the circuit with an input pin of our microcontroller to connect The output of the other circuit a TTL level did not have in such a way we the level over appropriate hardware e g optocoupler voltage divider Level shifter aka level transducers to adapt The mass of the two circuits must be interconnected naturally It is naturally finally no matter to the software how the signal is fed We can examine anyway only whether against a pin of our microcontroller a logic 1 tension more largely approx 0 7 Vcc rests or logic 0 tension smaller approx 0 2 Vcc Detailed information about it starting from which tension an input as 0 low and or 1 high is recognized the
106. rge also the header file lt stdbool h gt and to be put on then as used a Booltyp Variable this type need nevertheless 1 byte memory make however an exact distinction possible between number variable and boolscher variable Fundamental program structure of a uC program We differentiate between 2 different methods in order to write a microcontroller program completely independently of in which programming language the program is written Sequential program sequence With this programming techniques a continuous loop 1s programmed which has essentially always the same Structure Interrupt controlled program sequence With this method with the program start first the desired sources of interrupt are activated and then go into a continuous loop in which things to be settled to be able which are not time critical If an interrupt is released automatically the assigned interrupt function is in such a way implemented General accesses to registers The AVR microcontrollers have a multiplicity of registers Most of it are so called write read registers That is the program can pick out and describe contents of the registers both Some registers have special functions others again can for general purposes memory of data values be used Individual registers are present with all AVRs others again only with certain types So are for example the registers which are necessary for the access to the UART naturally only with those mode
107. ro eony Aa a 77 endif jj auxiliary macro for UBRR computation formula according Co data sheet define VART UBRR_CALC BAUD_ FREQ_ FREQ_ BAUD_ 16L 1 define UART_BAUD_RATE 9600 Age manod UBRRH Uin t VARI UBRR CALC UART BAUD RATE FE PU gt gt 6 gt UBRRL Gints CIUARI VERR CALC UART PAUD RAIE F PU A aleer na aae y with avr tabe directly the oo a UBRR VARI UBRR CALC VARI PAUD RAIE F PU Vee Partly one can look up the appropriate value in the data sheet of the respective CCU also An example of a ATmega32 with 16MHz and of 19200 Baud in the data sheet of the ATmega32 table Examples OF UBRR Settings one reads off the value 51 for these defaults This is distributed now on registers UBRRH and UBRRL The initialization for the USART could look then in such a way Ae Maln Oo Ike 7 USA biank INIT 19200 Baud with LOMI for MegasZ 7 UCSRB I lt lt TXEN UART TX switch UCSRE a UR ELIN a Ueo A asynchrones N UBRRH O High byte is 0 UBER sl Low byte is 51 decimally ie The above code is define in relation to the versions with not so portably but however somewhat more clearly Send individual indications In order to spend now an indication on the interface we must write the same only into the UART DATA registers Before it is to be examined whether the UART module 1s ready the indication which can be sent to receive The designati
108. rupt routines which are defined by means of INTERRUPTS there is no direct replacement in form macros Such routines are to be defined according to documentation avr libc in the following form vordi vece VO Eae r oaee N ner rupe Void XXxx vecli vold 4 Example include lt avr io h gt include lt avr interrupt h gt Vi oe INTERRUPT silG OVERE LOwo I5 K new XA Ay tinclude ary ie io Vi eae vonde TIMEROVOVE Vvece void Ss attribure interrupt void TIMERO OVF_vect void f Wants or if one cannot portieren the code the header file is to be merged compat deprecated h for the further use of INTERRUPTS One should however new examine on this occasion whether the functionality of INTERRUPTS is actually intended In many cases INTERRUPT was used where SIGNAL now ISR should actually have been used Became outdated functions to the Port access inp and outp to reading in and or writing registers are not necessary any longer the compiler supports this without this detour unesie d char als 64 2 VE BON ek Sgyos BAIN she Oia tree CUE OPO TE E new no longer really new L PINA T O PORTB j Wants or if one cannot portieren the code the header file is to be merged compat deprecated h for the further use of inp and outp Became outdated functions to the access to bits in registers cbi and sbi to resetting and setting bits are not necessary any longer the com
109. s Interrupt routines should be as short and fast processable as possible from this follows e No extensive computations within the interrupt routine e No long program loops e Although it is possible to permit during the processing of an interrupt routine other one or even the same interrupt again without exact knowledge of the internal operational sequence urgently one advises against Interrupt routines ISRs should be as short as possible thus and contain no loops with many runs Longer operations can be usually isolated into a interrupt part in a ISR and a working part in the main program E G memory of the condition of all inputs in the EEPROM in certain time intervals ISR part Time comparison timer RTC with log time interval During agreement a global flag set volatile with flag declaration forgotten do not see below Examine then in the main program whether the flag is set If the data in the EEPROM placing and flag delete Note There is however the rare situation that one must process straight read in ADC values immediately Particularly if one gets several values very fast clean other Then nothing else remains for one to process as the values still in the ISR Occurs however very rarely and should be avoided by suitable choice of the system clock and or selection of the microcontroller Sources of interrupt The following events can release an interrupt on a AVR AT9082313 whereby the sequence of the l
110. s are correct a file develops main hex in which the code for the AVR is contained 4 Programmers Notepad 2 File Edit View Window Help le Cal Line Endings F si W Lise Tabs L Win vF Make Clean EZ winavR Program Options W D tmp gcc_tut quickstart gt make all avr gcc GCC 3 4 6 Copyright C 2006 Free Software Foundation Inc This is free software see the source for copying conditions There is NO warranty not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE Compiling C main c avr gcc c mmcu atmegal6 I gdwarf 2 DF_CPU 1000000UL Os funsigned char f unsigned bitfields fpack struct fshort enums Wall Wstrict prototypes Wundef Wa adhlins obj main lst std gnu99 Wundef MD MP MF dep main o d main c o obj main o Linking main elf avr gcc mmcu atmegal6o I gdwarf 2 DF_CPU 1000000UL Os funsigned char funs igned bitfields fpack struct fshort enums Wall Wstrict prototypes Wundef W a adhlns obj main o std gnu99 Wundef MD MP MF dep main elf d obj main o output main elf W1 Map main map cref lm Creating load file for Flash main hex avr objcopy 0 ihex R eeprom main elf main hex arate Contents of the hex file can be transferred now to the microcontroller This can be made e g by in system Programming ISP described in the AVR Makefiles after the WinAVR Mfile main information collecting are prepared for the use of the program If
111. s that for the assignment by means of all pins are always indicated at the same time One should read thus if only certain outputs are to be switched first the current value in of the Port and let the bit of the desired Port into this value flow If one wants to set thus only the third pin bit No 2 at Port B on high and to leave the status of the other outputs unchanged one uses this form include ay Gy aon a PORTB PORTB 0x04 better PORTB PORTB 1 lt lt PB2 simplifies by use of the operator PORIB 1 lt lt PB2 e aoaaa a a ae a PORTE STT PEAT PES a a PATa a a 7 A switching off thus outputs on low set affected similarly include lt avr io h gt PORTB amp 1 lt lt PB2 bit resets 2 in PORTB and sets thereby for pin PB2 on low PORTB amp 1 lt lt PB4 1 lt lt PB5 pin PB4 and pin PB5 low In source codes which were developed for older version that of the avr GCC avr libc individual bits are set and or reset by means of the functions sbi and cbi Both functions are in current versions avr libc the no more contained and also not more necessarily If the initial condition of outputs is critical the sequence must be considered with which the data direction DDRx is stopped and the expenditure value PORTx is set For output pins which are initialized with Initial value high first the bits in the PORTx register set and afterwards the data di
112. s the sleep mode If the bit is deleted then the Idle mode is implemented If the bit 1s set then the power down mode is implemented for other AVR microcontroller see section Sleep mode ISC11 ISC10 Interrupt Scythe Control of 1 bit These two bits determine whether the rising or the falling flank for the interrupt recognition at the INT1 Pin is evaluated ISC11 ISC10 Meaning Low level at INT1 produces an interrupt j 2 In the description it is called the interrupt is triggered as long as the pin to 0 remains thus actually uselessly 0 l Reserved 0 The falling flank at INT1 produces an interrupt l l The rising flank at INT1 produces an interrupt ISC01 ISC0O0 interrupt scythe control 0 bits These two bits determine whether the rising or the falling flank for the interrupt recognition at the INTO Pin is evaluated ISCO1 ISC00 Meaning Low level at INTO produces an interrupt J 2 In the description it is called the interrupt is triggered as long as the pin to 0 remains thus actually uselessly 0 l Reserved 0 The falling flank at INTO produces an interrupt l l The rising flank at INTO produces an interrupt General look over interrupt processing If an interrupt arrives global the interrupt Enable bit in the status register SREG is deleted automatically and all further interrupts is prevented Although it is possible to set at this time already again the GIE bit I advise against urgently This is set autom
113. sters If a transformation is final the measured value is in these two registers Only the two least significant bits are used by ADCH Always both registers must be picked out always in the order ADCL ADCH The effective measured value results then too x ADCL Vie ite in Le neo x ADCH lt lt 8 in two lines LSB MSB sequence and C Operator priority guaranteed or x ADCW depending upon AVR also x ADC see avr ioxxx h ADC multiplexer SELECT register With this register the channel which can be measured is selected With the 90S8535 each pin von Port A can be used as ADC input 8 of channels The register is developed as follows 0 l 2 3 4 5 6 7 Bit MUX0 MUX1 MUX2 MUX3 MUX4 ADLAR REFS0 REFSI Name R W R W IW R W R W R W R W RAW R W 0 0 0 0 0 0 0 0 Initial value REFS1 REFSO ReferenceSelection bit With these bits the reference tension can be stopped Reference cutting REFSO REFS1 External AREF 0 0 AVCC as reference l 0 Reserved 0 l Internal 2 56 V l l ADLAR ADC Left Adjust Result ADMA The ADLAR bit changes the appearance of the suppl bite of the AD transformation With logic 1 the result is left justified spent with 0 right justified A change in this bit affects result immediately all the same whether a transformation is running MUX4 MUX0 With these 5 bits the channel which can be measured is determined If a simple 1 channel ADC is used write simply the appropriate pin
114. sts to find the possibility out whether a RESET was released by the Watchdog with the ATmegal6 e g bit WDRF in MCUCSR This information should be also used if a WD RESET were not implemented according to plan in application For example one can hang an LED to a free pin which lights up only with a RESET by the WD or secures however the event WD RESET in the internal EEPROM of the AVR in order the information e g over UART or a display to spend later or simply pick EEPROM contents out over the ISP JTAG interface e see also Documentation avr libc the section Modules Watchdog timer handling Program with interrupts After we taught now all that worth to be known for serial program preparation we now will completely start different topic 1 e programming with help of the interrupts of the AVR As the first we want to lead ourselves again the general program sequence during interrupt programming to mind One sees that the interrupt routine runs off quasi parallel to the main program There we only one CCU have are natural it no genuine parallelism but the main program is interrupted with the arrival of an interrupt the interrupt routine is implemented and to it only again to the main program returns Detailed Thread in the forum iseal ASit Cals 4 heii ai Requirements at interrupt routines In order to prevent unpleasant surprises some basic rules should be considered with the implementation of the interrupt routine
115. t PAx PBx PCx etc these definitions not use or can also simply always use even if that takes place access to bits in DDRx or PINx registers For the compiler the expressions 1 lt lt PC7 are identical 1 lt lt DDC7 and 1 lt lt PINC7 1 lt lt 7 more exactly the Preprocessor directives replaces the expressions 1 lt lt PC7 too 1 lt lt 7 A cutout of the definitions for Port C of a ATmega32 from the 10m32 h file to the elucidation similar for further Port 7 7 PORTC 77 define PC7 define PCE define PCS define PC4 define PC3 define PC2 define PCl define PCO amp WS amp Hs Cl oo Fo IDE Say define DDC7 define DDC6 define DDC5 define DDC4 define DDC3 define DDC2 define DDC1 define DDCO Is amp eS Ci oY 7 PINC 7 define PINC7 define PINC6 define PINC5 define PINC4 define PINC3 define PINC2 define PINCI define PINCO S amp S WS amp es Gi Gy Digital signals It is simplest to seize and or spend digital signals with the microcontroller Outputs If one wants to set defined pins appropriate DDRx bits 1 as output on logic 1 one sets the appropriate bits in the Port register With the instruction e LiiGle lt a 1 own PORTB 0x04 better PORTB 1 lt lt PB2 The output is thus set at pin PB2 consider that the bits are always counted from 0 the least significant bit is thus bit number 0 and not bit number 1 One note
116. t must be paid attention to the fact that the discharge process lasts sufficient long Now pin 2 is put on HIGH The condenser is loaded If the tension over the condenser the tension resting against the input pin reached connects through the comparator The time which is needed around the condenser to load can be consulted now also again as measure for the tension of pin 1 I saved it for me to also develop this circuit for several reasons 1 3 pin necessarily 2 Accuracy comparably with simpler solution 3 Was simply too putrid The advantage of this circuit is however in the fact that thereby directly tensions can be measured DAC digital to analog converter With the help of a digital analog converter DAC we can spend now also analog signals There are here several procedures DAC over several digital outputs If we develop at the outputs of the microcontroller an appropriate resistance network have we the possibility of developing by the control of the outputs over the resistances an adder with whose assistance we can produce a proportional tension for the numerical value The diagram in addition can look about in such a way ViCC Naturally if possible details of resistors should be used thus not necessarily such with a tolerance of 10 or more Further it is advisable to strengthen depending upon application output current over an operation amplifier PWM pulse width modulation We come now to a topic which is
117. t pgmFooByteArrayl PROGMEM const uint8_t pgmFooByteArray2 PROGMEM _ S0 W ail ee Pee ae WW J 7 gt pointer 47 const uint8_t pgmPointerToArrayl PROGMEM pgmFooByteArrayl const uint8_t pgmPointerArray PROGMEM pgmFooByteArrayl pgmFooByteArray2 eee voio fOO void Static const uint8_t pgmTestByteLocal PROGMEM 0x55 static 7 conse Char pgmlestotringLocalll PROGMEM an the Flash j SC NOt Static IS Missing char pomrescstinglocalralscn PROGMEM so not J 7 Byte read With the function out pgmspace h affected that pgm read byte access to the data Parameter of the function is the address of the byte in the Flash memory value of the RAM variables myByte to the value of pgmFooByte sets uint8_t myByte myByte pgm_read_byte amp pgmFooByte myByte has now the value 123 TT loop over an array from byte values in the Flash Uo we AL for i 0 i lt 3 it t myByte pgm_read_byte amp pgmFooByteArrayl i AO RACO WALON When yEy e ee Word read For simple 16 bit broad variable that takes place access similarly to the byte example however with the function pgm read word uinti6_t myWord myWord pgm_read_word amp pgmFooWord Pointers on values in the Flash are likewise 16 bits largely conditions avr GCC 3 4 x Thus the possible storage area for Flash constants is limited on 64kB urio ont wiciene
118. table DC Characteristics supplies in the data sheet of the used microcontroller The inquiry of the conditions of the Port pins is made directly by the register name About is important to use for the inquiry of the inputs not Port register PORTx but to input register PINx The inquiry of the pin conditions over PORTx instead of PINx is a frequent error with the AVR first contact Otherwise one reads not the condition of the inputs but the status of the internal Pull UP resistances If one wants to query signal statuses of Port D and into a variable named bPortD store current one writes the following command lines tinclude ari ier h gt tinclude stdin N uUlo e ole ence D bPortD PIND With the C Bit operation one can query the status of the bits saa e Ikke e aa o emo lement S ecaion ati bat Noa ue Ene Ssecoma DI To Seu n PIN a7 dee le UNG a C Ly y ae o a amplementes action 22 bre No 2 ene Eira bit 25 deterred am PINs 0 77 ft UP INBs 6 PTE a ae meri 7 i Keys and switches The connection of mechanical contacts at the microcontrollers becomes likewise completely simple whereby we must differentiate between two different methods Active Low and Active High Active High CC Eey INPUT AWR Here the contact is switched between supply voltage and the input pin So that during open switching position no undefined signal at the microcontroller is applied between the input pin an
119. te if denounce amp PINB PBO case button pressed to pin PBO PORTET APINE lt lt PD 7 2 re we PO Phy on and or swiech on 7 7 With this example it is to be considered that the AVR waits in case of a depressing the key 200ms therefore fallow lies Time critical applications should select another procedure To the topic debouncing see also e Article Debouncing Analog The processing of analog input values and the expenditure of analog values in chapters analog input and output are treated 16 Bit Port registers ADC ICR1 OCR1 TCNT1 and UBRR Some of the Port registers in the AVR Controller are 16 bits long In the data sheet these registers are usually with the suffix L LSB and H MSB provide Avr libc additionally most define this variables the designation without L or H These can be assigned and or accessed directly The conversion from 16 bit word after 2 8 bit byte takes place internally bake ble sive ae a include lt c tdine o uint 6_t foo fOO ADC 7 the word variable sets foo to the value of Ehe last AD transformation If needs a 16 Bit variable can be divided also quite simply manually into its two 8 bits of components The following example demonstrates this on the basis the pseudo 16 Bit of register UBRR rrn lude enya io h Pin uda e Sr Cliche 2a Pit Meet F CPU define F_CPU 3686400 endift define UART BAUD RATE 9600 typedef union babe dio wie
120. tern to an existing variable in addition with the keyword com m the necessary number of bytes for a variable is reserved zaehl asm S tine luce Tovro lav temp 16 iy comm zaehler 1 global INTO_vect INTO vecrt In the header file then to the variable only one refers keyword extern zaehl asm h ifndef ZAEHL_ASM_H define ZAEHL_ASM_H extern volatile uint8_t zaehler endif Contrary to global variables in C variables so put on are not initialized automatically with the value 0 Variable one more largely than 1 byte Variable ones which are larger than a byte can be responded in assembler to similar kind For this enough bytes must be only requested in order to take up the variable If a variable is to be used of the type unsigned long thus uint32_t e g for the counter then 4 bytes must be reserved 4 byte in the RAM for the counter reserve comm zaehler 4 The pertinent declaration in the header file would then be extern volatile uint32_t zaehler With variables which are larger than a byte the values are put down beginning with the least significant byte in the RAM The following Codes shows how can be accessed under assembler the individual bytes In addition in the interrupt now a 32 Bit counter is increased Hine Inala Toyir chy las een 16 4 byte in the RAM for the counter reserve zaehler counter just as notice Ahmed comm zaehler 4 global INTO_vect INTO vect R
121. terrupted by other interrupts with ISR are defined see section in the main part Also the designation were standardized and adapted to the usual designations into the AVR data sheets In the documentation avr libc old and new designations in the table are confronted The necessary steps to the Portierung e include from avr signal h remove e SIGNAL duch ISR replace e Name of the interrupt vector adapt SIG _ vect by appropriate As example of the adjustment first a old code include lt avr interrupt h gt include lt avr signal h gt Timer2 output Compare with a ATmega8 SIGNAL SIG_OUTPUT_COMPARE 2 In the data sheet the vector with TIMER2 COMP is designated The designation in avr libc corresponds to the name in the data sheet blank through would underline _ replaced and vect attached The new code looks then in such a way include lt avr interrupt h gt signal h escapes ISR TIMER2_COMP_vect With ambiguity concerning the new vector labels still a view helps into the header file of the appropriate MICROCONTROLLER For the previous example thus the view into the file 1om8 h for the ATmega8 there one finds the outdated designation below the current J ete Oma tia OOS Oy SO ae all eis at Oe GG tin Sein em ty J Bye Lone sdekini eros for Amegas 7 7 Timer Counter2 Compare Match define TIMER2 COMP _vect EVE TOR define SIG_OUTPUT_COMPARE2 EVECTOR For interruptible inter
122. terval between the change over of unloading on loading and the change of the input signal of High on Low is a measure for the resistance stopped at the potentiometer For time measurement one can be used in the microcontroller existing timer The 220 ohms resistance serves the protection of the microcontroller It would flow otherwise during maximum attitude of the Potentiometers here 0 ohms a too high river which destroys the input stage of the microcontroller With a further input pin and little software can we also a calibration realize around the measured value into a reasonable range e g to convert 0 100 or in such a way A sample program is on Christian Schifferles web page in archives ATMEL ZIP which under the title Tutorial programming with C for Atmel microcontroller can be downloaded ADC over comparator There is a further way to measure a analog tension with the help of the comparator which is integrated in nearly each AVR See in addition also the Application note AVR400 von Atmel The signal which can be measured is led on the inverting input of the comparator Additionally a reference signal is attached to the not inverting input of the comparator The reference signal is produced here also again over an RC element however with firm values for R and C VCC The principle of the measurement is now quite analog to the preceding By creation of a LOW level at pin 2 the condenser is first once unloaded Also here i
123. this bit is set with an overflow of the data pointer timer Counter 0 a timer OVERFLOW 0 interrupts is released Global the Enable interrupt flag must be naturally also set Timer Counter Interrupt flag Register Bit 7 6 514 3 2 1 0 Name TOV1 OCFIA ICF1 TOVO R W R W RAW RR R W R RW R Initial value 0 0 00 0 0 O 0 TOV1 Timer Counter Overflow flag timer Counter 1 This bit is set by the microcontroller if at the timer 1 an overflow of the data pointer takes place In the PWM mode of operation the bit is set if the counting direction from open closed downward and in reverse 1s changed counter value 0 The flag is deleted automatically if the associated interrupt vector is called It can be however also deleted by a logic 1 into the appropriate bit one writes OCFI1A Output Compare flag timer Counter 1 This bit is set if the current value of the data pointer of timer Counter agrees with that in the comparison register OCR1 The flag is deleted automatically if the associated interrupt vector is called It can be however also deleted by a logic 1 into the appropriate bit one writes ICF1 Input Capture flag timer Counter 1 This bit set if an Capture event arose which indicates that the value of the data pointer became to transfer timers Counter 1 into the input Capture register ICR1 The flag is deleted automatically if the associated interrupt vector is called It can be however also deleted by
124. ting of the vector designation 1s to be paid attention The GCC compiler examines only starting from version 4 x whether a signal an interrupt of the indicated designation is defined in the Inc loading file actually and spends otherwise a warning With WinAVR starting from 2 2005 the examination was integrated also into the provided compiler of the version 3 x From the GCC source code version 3 x provided compilers do not contain the examination see AVR GCC During the execution of the function all further interrupts are automatically closed When leaving the function the interrupts become again certified If a further interrupt same or other source of interrupt should arise during the processing of the interrupt routine then the appropriate bit in the assigned interrupt flag register is set and the appropriate interrupt routine after terminating the current function is called automatically A problem actually results then only if during the processing of the current interrupt routine several homogeneous interrupts arise The appropriate interrupt routine afterwards called however to know we not whether now the appropriate interrupt arose twice or still more frequently once Therefore it is to be again stressed here that interrupt routines will possible again leave as fast as only at all should Interruptible Interrupt routine Rule of thumb in the doubt ISR Those in the following described method use only if one realizes oneself the
125. tion as an output switch all connections of the port B become with DDRB Oxff as outputs e 4 Initialized values of the outputs Those first two bits of the port assigned port PBO and PB1 reach 1 all other connections of the port B PB2 PB7 0 If activated outputs logic 1 or high are on operating voltage VCC usually 5 V non activated outputs lead 0 V GND reference potential e 5 Is the major loop in such a way specified Main loop This is a program loop which contains continuously returning instructions In this example it is empty The microcontroller goes through the loop again and again without which something happened except river one uses Such a loop is necessary since there is no operating system which could take over control after completion of the program on the microcontroller If the loop would be missing the condition of the microcontroller became undefined after the program end in another words the program crashes TranslaToR cOMMent e 6 Tells us that the program ends here Contained only for reasons of C compatibility int Main void means that the function returns a value The instruction is however not reached since the program never leaves the major loop In order to translate this source code into a program executable on the microcontrollers a Makefile is used here The used Makefile is on the side example Makefile and is based on the Makefile generator the Makefile template in WinAVR is prov
126. tions Caution With old versions avr libc not all AVR MICROCONTROLLERs were supported E G with avr libc the version 1 2 3 with AVRs the functions do not function to the new generation ATmega48 88 168 169 in particular correctly a cause different storage addresses of the EEPROM registers In newer versions e g avr libc 1 4 3 from WinAVR 20050125 the number of the supported MICROCONTROLLERs was extended clearly and a method for easy adjustment to future MICROCONTROLLERs was introduced In each data sheet to AVR Microcontroller with EEPROM short example codes for the writing and read access are contained Wants or if one cannot update on the new version the code shown there can be used also with the avr GCC without avr libc eeprom h Copy paste if necessary protection from Unterbrechnung interrupts supplements uintS_t sreg sreg SREG cli EEPROM code SREG sreg return see section interrupt In the doubt a view helps into the assembler code lst Iss files produced by the compiler e see also Documentation avr libc the section module it EEPROM handling The use of printf In order to transact comfortably expenditures on a display or the serial interface offers itself printf sprintt a Ue oe cukon le ele lt Site Cristie A 77 not represented Implementation of uart_puts see section UART es Ubi igie E a void uart puti uintlo t value Hinto e Sol PENE eS Oe cell wellue a Dabew
127. to this register is calculated according to the following formula UBRR begin matrix mathrm UBRR frac mathrm Taktfrequenz mathrm Baudrate cdot 16 1 end matrix UDR There is more highly possible for Baud rates up to 115200 Baud and The hardware The UART is based on normal TTL level with OV LOW and 5V HIGH The interface specification for RS 232 defines however 3V 12V LOW and 3 12V HIGH Besides the signal exchange between AVR and partner equipment must be inverted For the adjustment of the levels and inverting the signals there are finished interface modules The most well known of it is probably the MAX232 If communication strikes by UART then an incorrect attitude of the Baud rate is often the cause The configuration on a certain Baud rate depends on the clock frequency of the microcontroller Straight ones with again developed circuits and or again bought control learn one should therefore make sure again that the microcontroller also actually works with the assumed clock rate and not e g uses the internal oscillator adjusted factory installed with some models instead of an external quartz The values of the different fuse bits in the event of an error thus for example with AVRDUDE control and if necessarily adapt In principle also always a view is recommended into the AVRChecklist Send with the UART We want to spend now data with the UART on the serial interface In addition we must initia
128. to unwanted side effects The proceeding evident from the following example is to be preferred in such cases include lt ayr wo lt include lt avr interrupt h gt e IMUCles lt ilighe ie joie 1a A vas Void NichtUnterbrechenBitte void uint8 t tmp_sreg of temporary memory for the status register tmp_sreg SREG status register thus also the I flag therein secure CEES interrupts global deactivate more unterbrechnungsfreier code example at the beginning of JTAG interfaces of a ATmegal6 by software deactivate here and thus the JTAG pins at PORTC for general I O usable make without the JTAG Fuse bits to change In addition one is timed sequence to keep vgl data sheet ATmegal6 Conditions 10704 FP 229 The JrD bit muse be Written twice within 4 clock ycles An interrupt between the two write accesses the necessary sequence to break the JTAG interface would remain further active and the IO pins further reserved for JTAG i MEUCSE E MCUCSR 4i lt lt 0 D gt J gt 77 2 bimes an consequence See data sieee fOr More in tormaelon example end SREG tmp_sreg status registers repair thus also the I flag on secured condition set vord Ni NE OCU elit more unterbrechnungsfreier code here o N IOC marn Ol Laer elas i interrupt global deactivates NichtUnterbrechenBitte yo PS Oued Ger 2G a aed e Emme Gaon MOCeCr an
129. touts from the source code exact error messages and or description of the failure In the case of control of external devices describe or outline the wiring e g with Andys ASCII Circuit See in addition also smart questions place Generating the machine code From the C source code the avr GCC compiler together with the Preprocessor directives and the linker produces machine code for the AVR microcontroller Usually this code lies in the Intel Hex format pronounced Hex file The programming software e g AVRDUDE PonyProg or AVRStudio STK500 plugin reads this file in and transmits the contained information the machine code into the memory of the microcontroller In theory only the avr GCC compiler and the linker with the correct options or parameters is able to generate a Hex file from C code however there is two main ways to generate this machine code e The use of an integrated development environment IDE with which all parameters can be accomplished e g in dialogue boxes Just as AVRStudio which can be used starting from version 4 12 free of charge with atmel com with WinAVR as plug in to form together an integrated development environment for the compiler avr GCC you must have AVRStudio and WinAVR to be installed on the computer Further IDEs for the avr GCC without requirement on completeness AtmanAvr C relatively favorable KamAVR free VMLab starting from version 3 12 likewise free of
130. uC that completely without effort of the program by hardware one counts up That alone would not be yet all too useful if not this hardware register could release an interrupt with certain counts Such an event is the OVERFLOWs Since those is limited bit width of the register it naturally also occurs that the counter counts so highly that the next count with this bit width is no longer representable and is put back the counters 0 This event one calls the OVERFLOWS and it is possible to this event an interrupt to be coupled Another area of application is the counting of signals which can be supplied by way of a I O pin The following remarks refer to AT90S2313 For other model types you must if necessary make some adjustments from the data sheets of the appropriate microcontrollers pick out We differentiate in principle between 8 bit timers which exhibit a dissolution of 256 and 16 Bit timers with logical proves a dissolution of 65536 When input clock for the timers Counter knows either the CCU clock frequency the output prescaler or a signal set on a I O pin is used If an external signal is used then its frequency may be not higher than half of the CCU clock The prescaler The prescaler serves to reduce the CCU clock for the time being by an adjustable factor In such a way divided frequency is supplied to the inputs of the timers If we work with a CCU clock of 4 MHz and adjust the prescaler to 1024 the timer is thus supplied
131. versions of the compiler support the access now directly and outp are no longer necessary Example Tloclude ayi conn INCM IAN VOL sets the direction register of the PORTA on Oxff all OTS aS OU CPU 7 DORA OII APOC CANS eC Ser ma Pa n Jel 00s a Dre T O and EEn n a To a PORTA 0x03 Write of bits One sets individual bits standard C conformal by means of more logically bit operations With the expression XS xe Veiner A 4 el o an a ls e X amp lt lt Bitnumber a bit is deleted in x The least significant bit for 1 of a byte has the bit number 0 the most significant for 128 the number 7 Example include avr io hN define MyBIT 2 PORTA 1 lt lt MyBIT MiSeES UO Nae e o e on 6 a PORTA amp 1 lt lt MyBIT deletes bit 2 at PortA With this method also several bits of a register can be at the same time set and reset Example LINC bela e aaa ao ae DOURAR 0 I lt PAON ent a PA ne PAO and PAS as Inputs 77 PORTA I lt lt PA0 1 lt lt PA3 Sineerneal Uli UP ET Or Ol Swi ech Onm In source codes which were developed for older version that of the avr GCC avr libc individual bits are set and or reset by means of the functions sbi and cbi Both functions are not necessary any longer See also e Bit manipulation e Documentation avr libc the section Modules Special Function of register Control rooms on a certain condition The
132. war oo sel jj interrupt global activates NichtUnterbrechenBitte Ve euGigiMate Veale alias oS Va elucidation of the unfavorable proceeding with cli sei elt interrupt global deactivates now Nichioocui ty after call of the function are interrupts this are global activated mglw Inadvertently Lae After now the interrupts are activated it needs naturally still the code which can be required which is to run off if an interrupt arrives In addition the definition a macro exists to ISR SIGNAL should not be used no more to the Portierung from SIGNAL to ISR sees section TODO left in the appendix ISR ISR replaces with newer versions avr libe the SIGNALS see appendix include lt avr interrupte h gt la ae ISR Vectorname before times SIGNAL siglabel with it Vectorname siglabel Interrupt Code With JSR a function for the treatment of an interrupt is introduced As argument for it the designation of the appropriate interrupt vector must be indicated These are to be found in the respective Inc loading files IOxxxx h The designation corresponds to the name from the data sheet with which through would underline the blanks are replaced and is _vect attached As example a cutout from the file of the ATmega8 with WinAVR standard installation in C WinA VR avr include avr iom8 h in the meantime the SIGNAL SIG_ no longer current apart from the current names for J
133. with a frequency of 4 MHz 1024 thus with approx 4 kHz If thus the timer runs then the data and or counting register TCNTx with this frequency is incremented 8 bit timer Counter All AVR models have two 8 bit timer at least partly even The 8 bits timer is addressed e g with AT90S23 13 via the following registers with other types as far as possible similar Timer Counter Control Register Timer 0 In this register we adjust as we would like to use the timer Counter The register is developed as follows Bit 71615413 2 l 0 Name j CS02 CS01 CS00 R W RRRRR R W RW R W Initial value O 0 00 0 0 0 0 TCCRO CS02 CS01 CS00 Clock SELECT bit These 3 bits intends the source for the timer Counter CS00 CSO1 CS02 Result 0 0 0 Stop the timer Counter are stopped l 0 0 CCU clock 0 i 0 CCU clock 8 l l 0 CCU clock 64 0 0 1 CCU clock 256 l 0 1 CCU clock 1024 0 l 1 External pin TON falling flank l 1 External pin TON rising flank If as source the external pin TON is used then a flank change is also recognized if the pin TON is switched as output Timer Counter data register timer 0 This is realized as 8 bit upward counter with writing and read access If the counter the value 255 reached begins it with the next cycle again with 0 TCNTO Bit 7 6 5 4 3 2 1 0 Name MSB LSB R W R W R W R W R W R W R W R W R W Initial value 0 0 0 0 0 0 0 0 In order to thus put and it with a frequency of 1 1024 tel
134. y the appropriate bit must be set on the Port If the pin is to be used as input the appropriate bit must be deleted We want to define thus for example pin 0 to 4 of Port B as outputs to write in such a way we the following line include lt a 7 ito be J RSerel nog menen on pen0 se sand 4 Vie ay sone OOO II Inercsloe aime dh DURE Oxi 7 SOL Trecteasstonment sine eariy a7 more tapping work however more clearly DIDI Vl lt lt DIDS i lt lt Ibis ib lt lt IDIDIS2 1 lt lt Iie il SDE some compilers permit the input of constants in the binary format e g GCC in WinARM starting from 1 2006 and in WinAVR NOT however from GNU GCC sources themselves erstellter compiler These writing wise thus do not use if code with others is to be exchanged DORB OOO Was direct assignment Clearer INOS sc eine 16 OOM orgie Is suede JOO Tany On bya wie ie mociiinneaw GCC 4 The pins 5 to 7 are switched there 0 as inputs Whole one of Port In order to define a whole Port as output the following instruction can be used DDRB Oxff In the example the Port B is switched as a whole as output In addition the header file must be merged avr io h in it DDRB is defined among other things Pre defined bit numbers for I O registers The bit numbers e g PCx PINCx and DDCx for the Port C are defined in the 10 h files avr libc and serve only the better legibility One mus
135. yStruct f Index 1 Te read of the data EEPROM index O in work eeprom_read_block amp work amp eeMyStruct 0 sizeof tMyStruct IA work label has now Che contents of corridor ieee TE EEPROM memory map in eep file A special function of the avr GCC is that with appropriate options in the Makefile from the start up values of the variables in the source code a file can be produced which one can program on the microcontrollers eep file Thus very elegantly default values for EEPROM contents in the source code can be defined The proceeding becomes evident from the WinA VR example Makefile See in addition the explanations in the section Exploring Makefiles EEPROM variable on firm addresses put Equal to beginning I would like to refer to that this procedure is only a Workaround with which one the problem that coincidental distribution of the EEPROM variables by the compiler something into the grasp apparent can get Helpfully this can be above all if one e g over a command interpreter 0 4 Functions directly determined EEPROM addresses to manipulate would like Even if one liked to manipulate the program sequence over an JTAG adapter mk I or mkII by changing the EEPROM values directly this technology can be helpful In the following now two SOURCE listings with an example GUT PPT TET PAID IITA ITI ALT II III ITT file eeprom h their own project GI TIT ET TE I I a F include
136. ype Bit fields When programming micro control learn must to each byte or even each bit be paid attention Often we must store the condition 0 or 1 in a variable only If we take to the smallest well known data types 1 e unsigned char now for the storage of an individual value then we waste 7 bits since unsigned char an 8 bit is broad Here the programming language C offers a powerful tool with whose assistance we can seize and nearly to us like 8 individual variables address 8 bits into an individual byte variable together The speech is from so called bit fields These are defined as structural components We regard in addition nevertheless best equal an example Stuer Unsetoned oStatmcr 77 wi SOne ror a Vacone do aa ae 7 Si ROtENGOre bc Grice Unsigned bNochNBit 1 and here once again a bit Unie tome cela Zin mins 72 VS ane ee Me Nels es OA GS Rhona universe that has in only one byte variable place 3 the remaining bits remain unused X That access to such a field effected now as with the structure access admits over the point or the Dereferenzierungs operator MOS terus eE x D9tatus 2 ZD BICOS a However perhaps bit fields save place in the RAM debited to of place in the Flash worsen the Les and maintenance of the code For beginners a whole byte uint8 t will turn out will use even if only one bit value to be stored is If one liked to use only a few variables of the type bool one can me

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