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ABCmini/ABCmaxi Manual

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1. OONOaRWDHD Port Group A Port 2 Also an A D converter input port digital I O when ADC disabled Port Group A Port 1 Also an A D converter input port digital I O when ADC disabled Port Group A Port 0 Also an A D converter input port digital I O when ADC disabled Port Group B Port 0 Port Group B Port 1 Port Group B Port 2 Port Group B Port 3 Port Group B Port 4 GND Second 5 Volt Supply for easy access on the opposite side of the ABCmini VCC Second 5 Volt Supply for easy access on the opposite side of the ABCmini Documentation for the ABCmaxi and ABCmini Version 5 2 Page 36 Ki Pin Functions and Circuit Details of the ABCmaxi The plethora of items on the ABCmaxi board is actually simple to understand have outlined the items can identify The pinouts for the screw terminals are shown in the ABCmaxi Circuit Diagrams section The Atmel AT90S8535 microcontroller in located to the right of the LCD connector The four small black components to the left of the MOSFETS are the opto couplers The MOSFETS are the four upright black components with a metal tab for a heatsink and three legs The chip with the marking LM4860M is a surface mount version of the LM480 audio amp The volume for this is controlled by the small variable resistor to the upper right of the 8MHz crystal below the LM480 chip The component to the right of the memory socket which is screwed to a heatsink is a 7805 fix
2. Not Connected Not Connected Not Connected Not Connected Not Connected Not Connected Port A 5 DB5 Port A 4 DB4 Port A 7 DB7 Port A 6 DB6 1 2 3 4 5 6 T 8 9 The original Maxi had three unused pads for a 10K ohm variable resistor for the LCD contrast Before production the variable resistor was removed and a zero ohm direct connection resistor was placed between the contrast pin and GND because the Maxi designer curse him decided that a contrast pot was not necessary although it certainly is on some LCD screens but the three pads were included If you have the original Maxi board you can remove the zero ohm resistor on the board and replace it with a 10K ohm trimpot Version 2 of the Maxi board does not have this zero ohm resistor at all and so an external pot must be used Some Extended Temperature displays require a negative voltage on the contrast pin to function In these cases you will need to find your own way to get a negative voltage to the CONTRAST pin of the LCD E Extra LCD wiring notes If your programming language or your code does not need the LCD R W Read Write Select Pin you can save yourself a port pin by connecting the pin straight to ground constant write mode It is also a good idea to connect all the unused Data Bit DB pins to ground to prevent scrambling of LCD text if the data bit pins are set momentarily high due to stray AC radiation Pushbuttons can be attache
3. VCC being positive voltage and RESET to reset the microcontroller s program once it is connected to either VCC or GND Later found out that this is activated by a low signal lasting more that 50ns assumed RxD and TxD were to do with transmitting data and receiving it by way of the serial UART black connector at one side of the board The white 5 pin connector identified by CONS on the diagram as a six pin connector but with only 5 leads from it that is used to communicate via the parallel port for programming had obvious functions connector pin 1 GND the computer ground was unused according to the Documentation for the ABCmaxi and ABCmini Version 5 2 Page 35 diagram pins 2 4 was programming in out and pin 5 the microprocessor reset Interestingly pins 2 4 are actually Port Group B Port 5 7 It seems that having an easy way to program the microcontroller sacrifices three of the I O ports Connector 1 power was also as obvious connector pin 2 was fed directly to the board s ground GND 5 volts and the power filterer and regulator a small 8 pin chip the middle row of its markings showing 2931 to the above right of the two pin power connector The connector pin 1 was fed into pin 8 of the power regulator whose output was connected to the board s VCC 5 volts m The miniature 3 pin IC marked with ABMY on my Hot Chip is a MAX6440UTEISD3 in charge of the RESET pin It is
4. The RS 232 serial communication protocol is a standard for device to device communications Most computers have a RS 232 communication port also known as a COM or Serial port although some modern computers are forgoing such legacy connections as the parallel Printer and serial ports in favour of USB Digital communication takes the form of a series of 1 s and O s A digital 1 is the logic voltage in the case of the AT90S8535 chip it s 5V or 12V for RS 232 serial and a 0 is ground negative power terminal on the AT90S8535 or 12V for RS 232 serial To translate signals from a series of 1 s and O s a language called binary is used Binary is a base 2 number system Each digital bit either O or 1 represents a power of two The first bit of a byte if one represents 2 0 or 1 the next bit being 2 1 2 and so on To convert a binary number from binary to decimal the base 10 system you use every day you need to add up all the bit values together A fantastic tutorial on binary can be found at http en wikipedia org wiki Binary numeral system and is definitely worth reading Because computers can only store numbers computer engineers needed a way of storing characters as numbers Eventually each character was given a specific numerical code which was called ASCII see http en wikipedia org wiki ASCIl To transmit data between devices the characters ASCII numbers are sent along a wire to the receiving device
5. The latest versions are already equipped to function with the HotChip boards but if you happen to have an old version open the prog settings file from your Bascom directory in Notepad Scroll down and if you do not see a HotChip or ABCMAXI entry add the following code HotChip BASE 378 MOSI BASE 1 CLOCK BASE 2 RESET BASE 4 MISO BASE 1 64 And save the file To select the programming method click Options Programmer and select Universal MCS Interface from the Programmer drop down box and HotChip or ABCmaxti either one will work for both ABC boards from the Universal Tab The next image shows a correctly configured programmer Documentation for the ABCmaxi and ABCmini Version 5 2 Page 41 BASLUM AVH Options Compiler Communication Environment Simulator Programmer Monitor Printer Programmer Univerzal MCS Interface Play sound e Z Erase waming Auto Flash vw Autoventy Upload Code and Data Parallel Serial Other Universal Default wu Ok x Cancel The above instructions need only be performed once after which programs can be downloaded by first connecting the 9V battery and parallel program lead then clicking Program Send to Chip and the Auto Program small green rectangle with black line button All users can purchase BASCOM AVR from the friendly and reliable Australian company Dontronics The Dontronics BASCOM purchase page is at http www dontronics
6. approximately 350ma please check the exact figure before approaching this value at 5V While this is perfectly adequate for the serial communications LEDs small circuits and even an LCD without backlight connecting high current devices will inevitably kill the regulator or cause it to become very hot As a result you should either use a second regulator to power these devices or adopt another method to limit the current wastage such as a switching regulator The maxi s onboard standard LM7805 with heatsink is designed for high current applications in the realms of a good half amp or so Polarity The cable which comes with the ABCmini is keyed so that it will only fit onto a 9V battery one way While this ensures that the battery can only be connected in the correct polarity the user may inadvertently touch the battery to the clip in the reverse manner giving 9V at reverse polarity into the delicate regulator Even the best regulators hate being powered in this manner so you should add your own method to ensure that this will not occur A standard diode would cause approximately a 7V drop on the supply input lowering the circuit efficiency and possibly degrading the life of the connected battery not to mention the lack of available space The easiest method to implement reverse polarity protection without the voltage drop is to use a fuse and a diode installed in reverse on the main power line before the regulator This is sho
7. or similar when soldering desoldering on the ABCmini board The 32 768KHz crystal on the ABCmini is circled red below And the maxi have had a report from a professional that the removal of the crystal is not necessary unless you are using a rapidly changing signal or high impedance signal the crystal can keep the port high after power is removed Leaving the crystal in place adds approximately 30pF of capacitance suggest leaving the crystal in place and only removing it if you experience trouble with the ports E Using Ports CO DO D1 and D2 ABCmaxi Port CO and port DO D1 and D2 are usually tied up with serial communications via the serial MAX232 chip or the RS 485 communication chip LT485 However the maxi board accommodates several jumpers for the selection between these two protocols located near the memory expansion slot and the left of the board To use the aforementioned ports all of the selection jumpers must be removed and connectors must be added in their place You could use a connector from an old PC case the jumper like connectors that link the case switches and LEDs to the motherboard or another method RS o Documentation for the ABCmaxi and ABCmini Version 5 2 Page 11 The jumper on the left is J18 located by itself at the left of the board The other jumpers J17 are located near the memory expansion slot E Earth Bonding the ABCmaxi cable After a power supply has been plugged in
8. com basc avr html E Programming in WinAVR firmly believe that the best software is free This is usually because free and open source software is embraced by the tightwads of the world and thus modified to death until the resulting application is as good as the writers can make it If you dislike the time consuming ASSEMBLER language and think BASIC lacks the flexibility you desire you may want to try WinAVR Pronounced Whenever this is a complex but powerful package containing amongst many other useful AVR tools the AVR GCC C language compiler for AVR microcontrollers Programs are written in a text editor of your choosing the free and brilliant Programmers Notepad program is included with the WinAVR installation package and compiled with the GCC compiler di ka ipla ti int ketucin weld 17 EAT mni npe iu T ader 1a ui Levi oni vl a mi cmo te Ti rt ime ET E Declara Imager vacat Pri Hn iam nue a mi j am ESTA 25 lan i JE adr X nm T4 ip He a EN ratur Er ey aif elise r ot opr ee Ti aj J fe LEGI me bres we zeta sui 5 Se ee ete EET D ayia Ea ima gei ba f z ef i ET 3 i apa E m iub VNUBER ri Piisi E lan T e I PTSCEN E F ur 1 To wah Pa piima rr r Tg Dac a q Piet 4F Pade The Programmers Notepad Interface Documentation for the ABCmaxi and ABCmini Version 5 2 Page 42 You can download the latest version of WinAVR at http winavr sourceforg
9. connected to the same ground as the regulated 5V The device s negative terminal should be connected to the Out on the MOSFET and the external supply e g 12V should be connected to the device s positive terminal The GND on the MOSFET should be connected to the common ground By applying a small voltage to the gate of the MOSFET via the 100 ohm resistor and 5V 20ma output of the AT90S8535 chip the MOSFET will conduct its GND and Out switching on the device Here s an example 12V o4 12V Relay 100 Ohms a 5V 20ma HotChip Output Comm nin round Both 12V and 5V E Multiplexing LEDs In many applications you will need a circuit that can drive many LEDs at once Regardless of the amount of I O s a microcontroller has you will inevitably run out or it will become impractical to program so many ports Consider the following display Documentation for the ABCmaxi and ABCmini Version 5 2 Page 29 This has four LED digits the active digit selected by a positive voltage to the Digit pins at the top and GND on the segments at the bottom Each segment should be attached to a port with a 220 Ohm resistor This is compact and easy to use but has the problem of only being able to light one digit at a time Fast microcontrollers such as the AT90S8535 used in the ABCmaxi and ABCmini can overcome this problem using a method called multiplexing COW pols cole poli Transistors are connected on the Digit pins as s
10. document before acting on any instructions and or advice Thanks to the following people for their correspondence apologies to anyone omitted e Malcom e Jim Manuel Gamelis Technichem e Philip e Nigel George Austrol e Tom e Jeffrey Gibson e Vignesh e Robert Gibson e AVR Technical Support Atmel e Ken Goldsmith e David Cary e Kel Skinner Investment Technologies e Carl Charpentier e James Stevenson e Erik Damen e C Thierry e Stuart Forge e Robert Turner e Neil Wrightson e Supplied Information e Requested Information e Gave Comments E Disclaimer ALL CARE HAS BEEN MADE TO ENSURE THE ACCURACY OF THIS DOCUMENT BUT ALL INFORMATION OUTLINED IS TO BE FOLLOWED AT THE USER S OWN RISK SOME CIRCUITS DESCRIBED ARE PHYSICALLY UNTESTED THE AUTHOR OF THIS DOCUMENT IS NOT LIABLE FOR ANY DAMAGES CAUSED AS A RESULT OF THE INNACURACY OF ANY INFORMATION OUTLINED IN THIS DOCUMENT OR ANY DAMAGES OCCURRED AS A RESULT OF THIS DOCUMENT BY ACTING ON ANY ADVICE INSTRUCTIONS INFORMATION CONTAINED IN THIS DOCUMENT YOU AGREE TO ALL TERMS DESCRIBED IN THIS DISCLAIMER IT IS IMPORTANT TO READ AND FULLY UNDERSTAND ALL WARNINGS AND OR CAUTIONARY NOTICES BEFORE ATTEMPTING ANY HARDWARE AND OR SOFTWARE MODIFICATIONS THIS INTELLECTUAL WORK IS PROTECTED BY INTERNATIONAL COPYRIGHT LAW IT MAY NOT BE MODIFIED WITHOUT PRIOR CONSENT FROM THE AUTHOR lt Me December 1 2004 Aged 15 This document is O Dean Camera 2004 2005 It may be photocopied
11. down low logic input Low Digital O Pull down high logic input High Digital 1 Port E Standard Transistors MFN FNP Unlike MOSFETs the humble signal transistor is not designed for switching high voltage high current loads although high power transistors are avaliable Transistors are cheap and very useful for switching circuits using a standard voltage With the ABCmaxi and ABCmini the power supplied is 5V via an onboard regulator and several hundred milliamps Due to the Atmel chip s design and the microscopic size of the parts inside the chip the AT90S8535 can output the full supply voltage of 5V but at only 20ma or so per pin This is only enough to run one low current LED not very useful A transistor coupled with a 1K ohm resistor at the output will switch the full supply voltage and current provided that the supply current is lower that the maximum rated for the transistor PCE PC5 Pod FCS PC2 PC1 FCO LEDI LED PIP DF PIFDE H m PAP DA GND Documentation for the ABCmaxi and ABCmini Version 5 2 Page 28 There are thousands of available types of transistors around in the world so you will need to check the specifications of your part In my examples use a bog standard BC547 approximately 40 cents from Jaycar This is a NPN type signal diode suitable for the above example Turning on PC1 will turn on both of the LEDs attached to that port s transistor Ela MOSFET Transistors MOSFET
12. each act as a digital signal NPN Open Collector Relays Requiring two I O connectors like the keypad module this board will switch 8 light duty less than 100ma loads via 8 separate open collector BC547 NPN transistors LED Board This add on board provides 8 LEDs powered by two 4 bit connector ports They each have current limiting resistors and are wired in a reverse logic formation low or digital O signal turns the LEDs on Documentation for the ABCmaxi and ABCmini Version 5 2 Page 6 Quad Relay Module Four relays allow medium heavy loads max 275VAC 5A or 35VDC 5A to be switched via a single I O connector Documentation for the ABCmaxi and ABCmini Version 5 2 Page CHAPTER 2 Introduction to Microcontrollers E What is the 8535 microcontroller The AT90S8535 microcontroller is a chip designed by the Atmel company to offer a fast and reliable way to perform many operations a second and have a wide range of uses Atmel makes a huge variety of these chips the latest series is the MEGA but the HotChip is based upon the slightly older 90x series Each microcontroller has a different amount of memory FLASH plus EPROM or SRAM or even all three Flash memory is present in every Atmel microcontroller and holds the program Flash is non volatile it is not erased when power to the chip is removed The
13. hiat ih oh eai b bm d e Biberi L m rs A modified version of Multiplexing exists called Charlieplexing a small diagram of which is shown above The Charlieplexing form of multiplexing uses even less pins to control many LEDs but requires more code for it to work correctly An application note on charliplexing is available at http www maxim ic com cn pdfserv en an AN1880 pdf E Multiplexing Pushbuttons Another form of multiplexing is a keypad This has a number of buttons joined into a matrix so that many buttons can be scanned using only a few ports The ABCmaxi or ABCmini is instructed to pull each output line rows low while another pin reads the column A logic high 5V indicates an un pushed button via the internal pull up resistor while a low logic level indicates an pushed button You will need to enable pull up pull down resistors or place pull up resistors externally for this method to work correctly A typical push button matrix looks like this Uu I m DL I As shown of the diagram you should place 1k resistors on each of the matrix rows and columns when connecting up the keypad matrix to your microcontroller This limits the current flowing from the output scan into the input and prevents damage if shorts occur There are several methods of scanning for pushed keys One way is to set all the columns as outputs and the rows as inputs with pull ups enabled Set all the columns hi
14. holds special chip options A good analogy for a fusebit is a row of DIP Dual In Line Package switches These are commonly used to set options on a circuit board and can be either Off or On The AT90S8535 and hence both of the ABC boards comes with two fuses and two lockbits Lockbit one is used to disable read write operations to the chip When this is set you cannot program the chip or perform and reading or writing operations until this lockbit is reset Only ChiplD Verify and Erase functions will work so you will have to erase the whole chip to be able to reprogram it This is ideal for commercial purposes after programming the chip and inserting it into the circuit set the lockbit to prevent hackers from stealing your code Lockbit two is slightly more secure it disables all commands except for Erase This means that hackers can t event tell what type of chip it is but it can lead to irritation when programming as the computer cannot tell when the Atmel chip is plugged in or not recommend setting this lockbit ONLY once the final tested code has been programmed onto the chip Fusebit One named SPIEN disables all serial programming This could be used if the SPI ports PDO and PD1 are needed for normal I O operations As a by product this also acts as the highest security setting on the chip as no more programming of the chip is possible via the supplied ABCmini cable DO NOT ALTER THIS FUSE ON THE ABC BOARDS and you will n
15. is placed inside a register A register shorthand for shift register is a special hardware circuit that can hold a single byte of information in binary form ready for manipulation In an 8 bit microcontroller a register can hold a value between binary 00000000 decimal 0 and binary 11111111 decimal 255 If a larger number is being calculated or manipulated six of the registers can be grouped together in three pairs to hold 16 bit numbers between decimal 0 and 65535 When performing an operation the microcontroller s processor uses registers For example if the microcontroller was instructed to add 16 with 3 and then subtract 8 it would e Store the value 16 into a free register e Store the value 3 into a second free register Add the two registers store result in the first register e Store 8 in the second register e Subtract the second register from the first and store result in first register Even though the task is only two simple mathematical operations the microcontroller requires 5 clock cycles to perform it The AT90S8535 micro runs at 8MHz 8 million cycles per second so each instruction would take approximately 12 5 x 10 seconds 0 000000125 seconds per cycle so the 5 cycles would take approximately 6 billionths of a second to complete The 8535 contains 32 registers that can be used for arithmetic mathematical operations plus many other control registers that change or return the status of the I O
16. non conductive sheet to raise the board hight enough for the tops of the pins to make contact with the pads if you choose the latter solderless method Because the pins are round as opposed to flat in a standard IC you can use Machined Pin sockets These are similar to regular IC sockets but have rounded holes at the top Two 20 pin machined pin sockets will also work you can use more than one together to make up the total 40 pins that the microcontroller s board uses If you cannot find a suitable machined pin socket s you can alternatively purchase a row of snap off machine pin sockets in groups of 32 you will need two of these at approximately AU 2 80 These are actually preferable as the supplied pins do not quite clear the crystal soldered to the bottom of the board and subsequently may not slot into the socket correctly Using the rows of pin sockets will ensure that the pins connect properly into the socket Another fix suggested by users is to cut the plastic connecting the IC sockets two halves together or to remove the extra crystal thus freeing up Port Group C ports 6 amp 7 but this will disable some of the timing functions see later section on how to do this To make Port A work even for non A D operations you will need to set up the AREF AVCC and AGND pins see circuit diagrams in Appendix chapter E Setting up the ABCmaxi Investment Technologies specifically designed the ABCmaxi like the ABCmini so it could be
17. ports and MPU features El The DDR PORT and PIN Registers The DDR register controls the function of the port Setting a DDR bit high will set the corresponding port bit as an output while a low value will configure the pin as an input Each port has its own DDR register named DDRA for port A DDRB for port B and so on To read the value of an input pin you must read the PIN register For example if Port A 3 was an input you would read its value from third bit of the PINA register When the pin is configured as an input the PORT register controls the pull up on that port pin As with the DDR register there is a separate PIN register for each port Outputs use only the PORT and DDR registers the PIN register does not affect the port s function Setting a bit high on a PORT register will set the corresponding port pin high Port Register Mode PORT PIN DDR Output High 1 ignored 1 Output Low 0 ignored 1 Inpt NoPul up 0 Pin Value 0 Input Pull up Enabled 1 Pin Value 0 You should be very careful when switching an output pin to an input pin as the PORT register may be set to an unexpected state causing problems in the program s execution EQ Internal and External Interrupts All the AVR devices include several interrupts An interrupt is similar to a Visual Basic Event a section of user defined code that is executed
18. resistors you must connect the sensor to GND not VCC For example a switch connected to the port must be connected directly to GND for the pull ups to work The internal pull up resistors can be activated by configuring the PORT and DDR registers see The DDR PORT and PIN registers section The Atmel microcontrollers use a balance system for determining whether a port is logic O or 1 A good analogy of the port pins is a set of old fashioned scales with positive at one end and negative at the other The port is read as high if there is more current flowing from VCC 5V to the chip than is flowing Documentation for the ABCmaxi and ABCmini Version 5 2 Page 26 from the chip to ground and vice versa Even if the current is very small like that which flows via the pull up resistor the port will still read high or low accordingly Note the negative symbol is used because it corresponds to the symbols on a normal battery The AVR microcontrollers cannot be operated with negative voltages over 1V Documentation for the ABCmaxi and ABCmini Version 5 2 Page 27 Graphical Representation High Impedance no input Fluctuating between High and Low the pin picks up stray charges in the air This can be used a seed for a random number generator Pull up no input High Digital 1 Pull up low logic input Low Digital O Pull up high logic input High Digital 1 Pull down no logic input Low Digital O Pull
19. the LCD connector on the maxi board Connect the circuits to the pins shown above on the ABCMaxi You should place three jumpers in the manner shown NB Although reversible this modification may damage your board if incorrectly wired Please read the disclaimer at the end of this document before attempting this modification E The SPI Port The AT90S8535 chip is equipped with a SPI port for serial non RS 232 communications Usually the TTL level signals produced to and from this port via the microcontroller and computer are for programming but it can also be connected to a large range of special function chips the most popular of which are external EEPROMs Other chips such as programmable frequency and A D chips are also available The programming cable used for the AT chips uses 5 wires the three outlined above the RESET pin on the microcontroller and a GND for the logic signals Several slave devices can be connected to a single master but the slave chip select pin SS must be held ow on the active chip and high on all other slaves Interestingly the slave devices cannot send data to the master until a transmission from master to slave has occurred because the incoming data activates the slave s internal shift register 8535 Pin Port B 5 MOS Serial Out Port B 6 MIS Serial In Port B 7 SCK Serial Clock Unlike the I C bus outlined below the SPI bus uses the slave chip select pin SS to activate chi
20. the arrow on the socket specifies Sources on the Internet indicate that this chip has been superseded with another chip that does not come in the correct PLCC socket so it may be difficult to find a place to purchase this device A 12V 100ma plug pack Dick Smith 12V 500ma plug pack is suitable must be connected to the power socket located at the front right or two wires of the same voltage to the screw terminal to the right of the power socket wire to the right or the centre pin on the DC jack Read the section on Earth Bonding before attaching any cables If you have a serial cable identical to that of the ABCmini plug it into the small black and rectangular socket located at the Maxi s front left Plug the parallel cable into the long black socket to the right of the serial port To indicate the use of the RS 232 Serial port you will need to set your jumpers appropriately These jumpers are located to the right of the memory socket Indicates not connected Indicates a jumpered connection Once you have set the jumpers and attached your inputs and outputs to the appropriate screw terminals see ABCmaxi circuit section you are ready to start programming and using the Maxi board Documentation for the ABCmaxi and ABCmini Version 5 2 Page 38 E The Included Software The software included on the CD is called ABCEDIT This has an industrial appearance read complex with many menu commands This software can also be d
21. you can use a simple circuit connected to the maxi to allow transmission and reception from both protocols so long as only ONE protocol is active at a time 234 Rx JP2 Above is the dual receive circuit The XOR you can also use an OR chip allows either signal to enter the UART Receive pin or the Rx pin on the AT90S8535 If both signals are received at the same time the XOR will give a constant low logic 0 output standard OR chips will give a logic 1 If the chip is halfway through a transmission when the other communication protocol sends a message the AT chip will become confused resulting in a garbled input A more advanced version would use a port pin to control access to the input 232 Ix UART Tx This dual transmission circuit is slightly more complex than the receiving one above A high signal on the Select Port pin will send data through the RS 232 communication port and a low will result in data being sent through the RS 485 protocol The circuit relies on standard TTL logic gates to perform the switching the inactive protocol will be pulled low Both circuits can be integrated into a small board and connected to the correct jumpers on the maxi The logic chips will also need an appropriate 5V supply from the on board regulator Documentation for the ABCmaxi and ABCmini Version 5 2 Page 17 232 Rz faz Tz 485 Tz AYR Rz These jumpers are located to the right of the memory expansion slot and near
22. 11 amp 12 TxD RS232 J17 short 5 amp 6 RS485 J17 short 9 amp 10 Opto 3 or Con 4 3 J11 amp J15 or RS232 CTS J18 Opto 4 or Con 4 4 J12 amp J16 Con 5 8 Con 5 7 and Audio amp Con 5 10 Con 5 9 and RS232 RTS Documentation for the ABCmaxi and ABCmini Version 5 2 Page 3 CHAPTER 7 Programming the ABC boards E Incorrect ABCmini Cables When the ABCmini was first being manufactured a batch of programming cables for the ABCmini were made but were incorrectly wired These cables will not work but as far as know these bad cables will not permanently damage the ABCmini although it would be a wise course of action to check the wiring of your cable against the table below You could use a multimeter continuity tester or any other go no go device The cable issue was sorted out many years ago before Austrol took over the manufacturing reigns but there are several companies mostly outside of Australia that may still be selling old stock Connector Pin 1 Connector Pin 4 Connector Pin 2 Connector Pin 3 Connector Pin 3 Connector Pin 10 Connector Pin 4 Connector Pin 2 Connector Pin 5 Connector Pin 19 E Preparing the ABCmini for programming To prepare the ABCmini first attach the 9V battery connector to the board This connector is keyed in such a way as to ensure that it can only be mated to the small 2 pin white connector on the ABCmini board in the correct orientation The serial cable should be connected ne
23. 2 PORTE 3 I O DPTO PORTC 5 I O MOSFET Plot ase eee Sees sees SS MAY BE CONNECTED aid T T Ji 1 2 e 3 g 3 PORTD 2 10 PORTE 0 I D MOSFET a w IN TECH BN JIS l z khkk hak ag ABC MANDA 27 1 s SS Ju Jl E m 47 B CIN4 a e BS SEs simis SEs airs oia e cae lale a 2 oe Izo E al Me 1 8 een 99 scr pom tores eso 00 oos ood OL UME Sv 14A lare amp olga Iure o g 2 z als sjaje oiie sjujo 9 oi u T0525 ves JdALOLO d LILLE BERE Hole og mG od oo jo oie ict Cc anpnocoomocuoaocuD CON T EB n0 mo Bore ae ee Bock m hva ce AD Drees rept tf Tarh ois i f ABCmaxi Overlay Version Z C Investment Technologies PRES PARALLEL PROGRAMMING FS 85 POWER IM 9 TO J5 in m s EQ Circuit Diagrams for the ABCmini and ABCmaxi li ba DCD 1 1 F G j arri DES R D 2 2 THO i i fe THO 3 3 A O OTR 4 4 ATS amp sa 5 3 CTS DSA 5 5 OSA z RTS T T SG e CTS 8 DCO Ring Indicator Sx 20 OTR E Serial Cable for Mini Maxi 9 pin to 25 pin Serial Cable Documentation for the ABCmaxi and ABCmini Version 5 2 Page 48 Load 1 IR F512 100 Ohms Port 4 OOo 47K Load IR F512 100 Ohms Port C 5 ma 47K T Load IRF51Z 100 Ohms Port B 0 3 j 47K T Load IRE a he PertB zi 100 ohms Voltage MAX 6 AMPS EE aK gt EG AT90S8535 package diagrams TRITT E 40P6 Package 44A Packag
24. AT90S8535 has 5Kb of Flash memory which will hold several thousand assembler commands of code Flash is a robust memory but has a relatively small write cycle lifetime that of 1000 for the 90x series After the chip has been reprogrammed more than approximately 1000 times programming errors will occur and a new microcontroller is needed The newer MEGA series have a write endurance of about 10 000 cycles EEPROM Electronically Erasable Read Only Memory is similar to Flash but it stores data that is not part of the actual program such as data logging data variables or settings and is also non volatile EEPROM is programmed separately to Flash and can be modified by the microcontroller program Most designers will make a generic program and have the settings for a specific device stored in EEPROM EEPROM s 100 000 write cycle rating makes it a good choice for storing data The 8535 has 512 bytes of internal EPROM Finally SRAM is similar to the RAM inside a normal computer it holds variables and other data in real time All declared variables that are not stored in EPROM are stored in SRAM and can be updated or read at any time SRAM is volatile wiped when power is removed and will last as long as power is supplied to it SRAM has an unlimited rewrite cycle rating and the 8535 contains 512 bytes All microcontrollers just like a computer CPU require a clock source Each pulse from the clock tells the microcontroller to execute an i
25. Australian Wiring Standards ensure that all households have an earth spike connected to the mains earth NB NEVER PLUG YOUR MAXI OR ANTI STATIC GROUNDING WRIST STRAP INTO A MAINS PLUG THAT DOES NOT OFFER COMPLETE INSULATION FOR THE ACTIVE AND NEUTRAL PINS UNLESS IT IS PASSED THROUGH A TRANSFORMER TO A SAFE VOLTAGE LEVEL FIRST E Running two chips from one crystal Interestingly have found that two AT chips can be run off a single which will make certain both chips are in perfect sync This is a good idea to reduce the number of parts lower the price and simplify the wiring of a large project Only two chips can share a TTL level crystal so more than two chips will require more crystals The diagram below shows how to connect a single 8MHz crystal to two AT90S8535 s using this configuration both chips will run at the crystal speed of 8MHz ole Le LT Ta Any clock source can be connected to the XTAL inputs of the AT chips an active oscillator provides a clock source with only one wire needed can be connected directly to the XTAL1 input or passive oscillators like quartz crystals can be connected to both inputs for the internal oscillator All passive oscillators must be parallel resonance to work correctly E Overclocking your 8353 chip have read on the Internet and seen many examples of overclocked Atmel chips i e chips that have a higher speed crystal attached than officially recommended The AT90S8535 chip
26. Dick Cappel s Hs Mostly wireless and YeYeYvdvo BEDV spoliis iiti www binary Very advanced page on connecting an IDE hard drive to an AVR EM www ingdm se avrdev avrdev htm dm se avrdev avrdev htm Minimal information with a small amount of projects and software www omegav ntnu no avr resources php3 Hundreds of AVR links but many are dead www riccibitti com index html Fantastic simple projects Shows how to send and receive a SMS from an Ericsson T10S YTYTYIYITYT GSM Mobile www site uottawa ca jdesa066 avr1 html Good but small site with a Getting Started for AVR microcontrollers and the C language www serasidis gr Some great projects Reading SMS Messages Phonecards as Keycards Graphical LCDs etc ages zoom co uk andyc A fantastic attempt at connecting a B amp W images on a computer at 8fps No AVR s here but another attempt at ARA O interfacing with a GameBoy Camera WWW zWs com products index html A couple of interesting Microcontroller projects SF5r5F home wanadoo nl electro1 avr outlines htm Shows the different component packages E Crore www avrbeginners net Nice little site Includes a Getting Started for the ASSEMBLY language Documentation for the ABCmaxi and ABCmini Version 5 2 Page 52 www dontronics com Australian company that sells the ABC boards plus many other components and kits Is well dropar pF known for its fantastic customer service www futurlec com au international
27. Documentation for the ABCmaxi and ABCmini Version 5 2 Page 19 With ABCedit the BASIC command to enable the Watchdog is enable watchdog cycles The watchdog cycles parameter can be omitted to set the watchdog to 2048K cycles or one of the following values can be specified 16 000 cycles 32 000 cycles 64 000 cycles 128 000 cycles 512 000 cycles 1024 000 cycles 2048 000 cycles To prevent the Watchdog from resetting your AVR chip you must inset a pat command in ABCEDIT in the main loop To force a reset a kick command must be executed 256 000 cycles BASCOM uses different keywords Config Watchdog xxxx where the xxxx is cycles such as 2048 command is used to set up the watchdog and a Start Watchdog command to start it Instead of the pat command used in ABCEDIT BASCOM uses the keyword Reset Watchdog Watchdog is invaluable when a lockup could cause hardware failure for example when a LED matrix is being driven without current limiting resistors scanning speed prevents LED from burning out to increase its brightness and reduce cost In this situation a lockup would cause the LEDs to destroy themselves The watchdog would prevent this by resetting the AVR when not reset via the program E Fuses on the 8535 Most if not all AVR chips come with fuses and lockbits A fuse is a specially allocated CMOS memory cell able to store ON 0 or OFF 1 fuses use reverse logic that
28. FILL HOLE IN FIN OR GND TO GND FUN DOWN THIN END CC TU WCC DO NOT BRIDGE ce Lo 3 m C e pxo3o d gt Teese oe GNDeE38o ce L2 k c Fo cL Digram C Investment Technologies TYFiCAL ARC MIHI hH LUCHE POWER CROHMD AND REFEREARCE Hn 5 i 5 5 L L L E F 1 d a 5 3 1 a J d 5 j WY doit GROUND AT CENTRAL FO Pl 7J 777 7J ers es es es Bers me aa MMMM TTF eee A SOI Documentation for the ABCmaxi and ABCmini Version 5 2 Page 46 B ABCmaxi Circuit Diagrams ENS eH Me eot oi X Wi e sls dir d F C i won AE 5 A N Lee 3 M oT eR epee Tow DESC zi Mo i EER Si Overlay of the ABCmaxi Version I Released in 1999 Uses a DIL version of the AT90S8535 Note the prototyping area mU pun EESTI i Seria e BOE INAI nx aua maimed x y A ME T nS erg Py ie IET fi ire i p yc oe FA E E Em SSeS S Wo Tom i Mas uem of the Al the ABCmaxi Version 2 Released in 2000 Uses a Surface Mount version of the AT90S8535 Prototyping area wire wrap 20 13 13 Parallel Programming Cable for the ABCMaxi Documentation for the ABCmaxi and ABCmini Version 5 2 Page 47 CIN JUMPERS COUT JUMPERS eau a CINI COLTI TT E PORTE 1 0 PORTE 4 Fall MOSFET r1 Em Sf oo um Pi ika z Le i a ee ee ig ee UTI ii a MOTE Pee ee DEI SO ee ee gt FIR OPTO INPUT CIN2 COUT PROR TOR Ree r rrrzggdggutsg 11 AND 1
29. U oficio Documentation for the Atmel AT90S8535 Microcontroller and Investment Technologies ABCmini amp ABCmaxi Boards Dean Camera 2004 2005 http home pacific net au sthelena Version 5 2 qmm 5 2 MAAAAIIINEYYTYIY asA s SANE ATW PAESE 000000000000900 0909909090009090 0090 0 ABCmaxi The ABCmini and ABCmaxi board are designed by Investment Technologies Pty Ld Boards are manufactured by Austrol Pty Ld Hot Chip is a registered trademark of Dick Smith Electronics www dse com au The ABC Edit program is Investment Technologies The AT9088535 is manufactured by the Atmel Corporation www atmel com ABC is an acronym for AVR Basic Controller AMEL The Investment Technologies HotChip boards use Atmel AVR AT90S8535 microcontrollers Documentation for the ABCmaxi and ABCmini Version 5 2 Page 1 Preface After waking up to a sack bulging full of presents on Christmas day 2003 was delighted to unwrap a white box bearing a large picture of a microchip and the letters Hot Chip Starter Pack had seen advertisements for these Microcontrollers before but to my dismay they all had a price tag of over AU 90 which was well out of my then 14 year old budget for interesting items that had no current need for had saved up my money a few years ago and had bought an AU 379 LEGO Mindstorms 1 5 pack containing LEGO pieces software and a programma
30. a low GND signal for more that 50ns VCC 5 volt power supply GND Power supply ground RxD Data Receive Can be used as Port Group D Port 0 if the UART is off TxD Data Transmit Can be used as Port Group D Port 1 if the UART is off Port Group D Port 2 Also External Interrupt 0 Port Group D Port 3 Also External Interrupt 1 Port Group D Port 4 Port Group D Port 5 Port Group D Port 6 Port Group D Port 7 Port Group C Port 0 Port Group C Port 1 Port Group C Port 2 Port Group C Port 3 Port Group C Port 4 Port Group C Port 5 Port Group C Port 6 Real time Clock Crystal input Port Group C Port 7 Real time Clock Crystal output AVCC Supply voltage for the A D converter Connect to VCC via a low pass filter AGND Ground for the A D converter If the board has a separate analogue ground plane this pin should be connected to it Otherwise connect to GND AREF Analogue reference input for the A D converter For A D operations a voltage in the range of 2V to AVCC must be applied to this pin Port Group A Port 7 Also an A D converter input port digital I O when ADC disabled Port Group A Port 6 Also an A D converter input port digital I O when ADC disabled Port Group A Port 5 Also an A D converter input port digital I O when ADC disabled Port Group A Port 4 Also an A D converter input port digital I O when ADC disabled Port Group A Port 3 Also an A D converter input port digital I O when ADC disabled
31. address is A company that has exceptionally low prices www futurlec com and will ship to almost anywhere www austrol com au Manufacturers of the ABC boards STYTTTYT http winavr sourceforge net Source for the free AVR GCC C compiler TTTTTITTTI http www smileymicros com Free Getting Started manual for the WinAVR GCC package extensive book on learning C SP ET ETP Era for microcontrollers Thanks to Investment Technologies Pty Ld for granting permission to use their copyrighted images in this document Also thank you to Atmel for their kind permission for the use of their copyrighted pictures in this Alm EL document and their help in supplying some of the obscure technical details rem Ms i E A final thankyou to Austrol Pty Ld for their support and assistance The pictures used on this documentation are Dean Camera or sourced from Atmel Corporation Investment Technologies Pty Ltd Austrol Pty Ltd or other website listed above If an image has been included and the source is not listed please contact me with your details This document in its current form is unofficial and thus some or all information contained is unsupported by Atmel Austrol Investment Technologies and or other sources Permission for content has been attained but said companies cannot guarantee the accuracy of information and or suitability of modifications described Please read the below disclaimer for this
32. another refresh cycle LED s can come packaged in a matrix connection like this TCO7 11HWA This has internal connections like the LED matrix shown above Add several together to create a moving or static display lh 4 could not find this part in the DSE or Jaycar catalogues it might need to be ordered specially off the Internet Check your local electronics distributor Documentation for the ABCmaxi and ABCmini Version 5 2 Page 30 When using the LEDs remember that a 270 ohm resistor is needed on the column OR row suggest using the column as there are fewer resistors required Normally when using multiple LEDs the 220 ohm resistance is divided by the total number of LEDs being driven this is ONLY for transistor switched LEDs not LEDs driven directly from the ABCmini ABCmaxi ports to give a final answer but since only one LED is on at any one time but driven so fast as the human eye can t tell the difference the resistance need only be suitable for one LED Larger displays or complex programs may need the transistor as an entire row might need to be shown at a time to prevent flicker but smaller displays or simple programs shouldn t need this E n mE 2 bn rr it TTT UCUFTTT M ME EE uda epu n HI PURA ERU HT x vu Pla 1 i ai i 4 LE a LE F it tb fe fe iol id oso i Beech Budd iy ll ILLE EILILLILLI zsalLL L 1I LLLI m 71 Tre 14 E barinn biisit dirite
33. ath the Processor dropdown list box there should be AT90S8535 repeated in the grey space While not required this step indicates that all is going well and the computer has found the chip successfully The device code for my ABCmini is 30 147 3 indicated in the white box in red text If you receive errors like Atmel Unknown or an invalid device code try changing the battery even if it checks out Ok in a multimeter as this happened to me sending me into oh my god ruined it panic Press the cramped BlankChk Blank Check button If the message BLANK appears then the AT90S8535 s memory is blank and ready to receive a program If the microprocessor is not blank click the Erase button and then Yes to the dialog to wipe its memory The program may also return OK if there is no power to the Hot Chip so make sure the battery is plugged in When the chip is blank and ready click the Program button The progress bar below the File pane will show the download progress When this is complete the program will automatically verify that the program has downloaded successfully You can check at any time by pressing the Verify button on the right of the Program button If your program does not download correctly try increasing the PROG Delay text box at the bottom of the screen from its default 250000 The manual says fast machines may need a delay of 750000 but don t believe it my 1 2GHz PC neede
34. be noted that it is not an exact process and take NO responsibility for any damage to your microcontroller as a result of this procedure An extract from a reply received from the Atmel Technical Support on the subject offers the following caution Even though this might seem to disable the programming interface other functions in the device may also be damaged Characteristics of the device like power consumption life time or ESD structures may change in the process The following pictures are courtesy of SXPilot450 from the AVRFreaks net forums Unaltered 8535 internals Blown pin 2 from top Close up of the good pin Close up of the blown pin If after an attempt at blowing the MISO pin the device can still be verified try applying the voltage for a longer period It should be noted that blowing the pins does not protect your micro against invasive attacks where the pin can be bypassed by skilled hackers with precise equipment and a lot of time on their hands Eta Pulse width Modulation Most microcontrollers the 8535 is no exception have the facility to perform Pulse Width Modulation commands PWM commands to control the speed of motors In short PWM rapidly cycles an output Documentation for the ABCmaxi and ABCmini Version 5 2 Page 21 port at a desired frequency at the supply voltage 5v usually to speed up or slow down a motor Since digital IC s can t output an analogue voltage variable voltage t
35. ble brick LEGO Mindstorms information is available at www legomindstorms com This set was a great introduction to Microcontrollers I still love it as the chunky yellow brick that was the core of the set had a small computer programmable Microcontroller inside This was very easy to use as the software is picture driven and downloads through an IR infra red link to the brick had resisted experimenting with Microcontrollers before was the apparent difficulty programming them and their price read issues of the Australian electronics magazines Silicon Chip and the now ceased Electronics Australia with many of the articles showing complex programming and devices required to program the external EEPROM memory ICs am an avid user of Visual Basic 6 and was even more excited to find that the Hot Chip supports BASIC and ASM Assembler code and has an easy to use cable interface with the computer The words Quick Start Manual and Hints on the box rose my hopes even more When installed the software however found the quick start manual to be mediocre at best With a bit of searching of the software s help file you can find out how to make basic programs in the ABCedit program and with even more searching you can find out how to download a program to the microcontroller chip The software is functional but easier and more powerful software packages do exist For my 15th birthday on the 14th February 2004 Valentine s day
36. can be overclocked to about 10 or 12MHz but would not recommend exceeding this Note that overclocking an Atmel chip can reduce its lifespan or make its performance unstable Overclocking will not cause any heat issues however at higher than rated speeds random instructions may be carried out and features such as the EEPROM may become unstable in operation Overclocking can have some benefits however as the extra speed can come in handy A man named Igor has managed to overclock an AVR chip not an 8535 to directly connect it to the USB port at low approx 1Mbs speed Details of his project are available at http www serasidis gr Documentation for the ABCmaxi and ABCmini Version 5 2 Page 12 Overclocking will most likely lead to an inability to program the device Users suggest using the 8MHz crystal for programming and then switching to the higher speed crystal for running the program after it is completed I m interested in knowing just how far an AVR can be overclocked reliably I ve seen simple programs executed on an ATTINY2313 running at over 20MHz up from 10MHz or so but if you overclock please send me the details including what internal systems your program uses your chip type maximum rated speed and your overclocked speed Documentation for the ABCmaxi and ABCmini Version 5 2 Page 13 CHAPTER 4 Bits Bytes and More E Microcontroller Registers When data is being manipulated inside the microcontroller it
37. controller Why Atmel The separately available AT90S8535 Chapter 3 Getting Started Setting up the separate 8535 chip Setting up the ABCmini Setting up the ABCmaxi An alternative Serial connector Using ports C6 and C7 Using ports CO DO D1 and D2 on the ABCmaxi Earth Bonding the ABCmaxi cable Running two chips from one crystal Overclocking your 8535 chip Chapter 4 Bits Bytes and More Microcontroller Registers The DDR PORT and PIN registers Internal and External Interrupts Introduction to Digital Communication Using the RS 485 communication protocol ABCmaxi Dual communication protocols on the ABCmaxi The SPI Port The C Communication Protocol Using the Watchdog Fuses on the 8535 Pulse width Modulation Chapter 5 Connecting to other Devices A note about power requirements Sinking and sourcing current Unused port pins Interfacing with the ABCmaxi s opto inputs Wiring up an LCD to the ABCmini Wiring up an LCD to the ABCmaxi Extra LCD wiring notes Pull up and Pull down resistors Standard Transistors MOSFET Transistors Multiplexing LEDs Multiplexing Pushbuttons Driving 6 LEDs with 5 ports Controlling 6 wire stepper motors Chip to chip Interfacing Chapter 6 Pin Functions and Circuit Details Pin functions of the separate 8535 Pin functions and Circuit Details of the ABCmini Pin functions and Circuit Details of the ABCmaxi Documentation for the ABCmaxi and ABCmini Version 5 2 Page 3 Chapter 7 Programmin
38. d a delay of 1750000 more than double the stated delay to work correctly Clicking on the Run button will execute the chip s program To stop it click the Reset button Documentation for the ABCmaxi and ABCmini Version 5 2 Page 40 E Programming with BASCOM The included ABCedit software that comes with the HotChip microcontroller boards is functional but I STRONGLY recommend that all AVR users stick to one of the many other programmers available many of which are free Personally use BASCOM AVR This has a much nicer colour syntax interface and many great features Beginners will find the program easy to use and was able to write a complex program after approximately 6 hours 3 hours over 2 days A demo is available from MCS Electronics only programs under 2k can be compiled just search for BASCOM in your favourite search engine AVR Simulator Once you have created your program you can simulate it by clicking Program Compile or F7 When the process is completed click Program Simulate or press F2 By clicking on the small Play button you can execute your code and can see a visual representation of the ports by clicking the Show Hardware button If you find that the program execution is too slow add a Sim command to the start if your program and recompile This will cause the simulator to ignore wait commands it must be removed before programming Downloading your compiled program is easy in Bascom
39. d to the LCD data bit pins if you can enable and disable the LCD via software The pushbuttons MUST have a diode to prevent the data bit lines from being connected together when multiple buttons are pushed at the one time The next image shows how to rig three buttons The above example uses Port D bits 4 8 but you can use any port you wish To read the buttons first disable the LCD and send all the data bit lines Port D bits 4 7 high If Port D 8 is low no buttons are pressed and the LCD should be re enabled or disabled until new text is to be sent to the LCD In the event of Port D 8 being high all the data bit pins are sent low and then each individual pin is pulled high and the control line Port D 8 is read a high value indicates a pushed button You will also need to add a 1K resistor to the control line Port D 8 to ground to act as a pull down resistor See next section or you can enable the internal pull ups and invert the logic There is a brilliant and free LCD documentation available on the Internet at http www mil ufl edu imdl handouts Icd fag htm This page is the equivalent of a datasheet for the Documentation for the ABCmaxi and ABCmini Version 5 2 Page 25 most popular driver chip the HD44780 or clones such as the chip used on the Dick Smith LCDs but with longer and human understandable descriptions and explanations E Pull up and Pull down resistors For a digital chip to register values correctly on o
40. e 44J Package Documentation for the ABCmaxi and ABCmini Version 5 2 Page 49 Package images above are from the Atmel AT90S LS 8535 Documentation see bibliography Ed BASCOM Programming Flowchart Select Chip TyperPraegramming Method Insert Battery and Cables Press Auto Program Button Did program werty gt NO Change batteries and check cables YES Finish Documentation for the ABCmaxi and ABCmini Version 5 2 Page 50 EG ABCedit Programming Flowchart Select Chip Inzert Batters Read Device Codes Replace Battery le C ct Chip Found gt No NE eo and Check Cables YES ls Chip Blank MO Erase Chip YES ls Progrem Verified YES Use In Circuit Ho Increase Timing Delay EQ Standard LCD pin descriptions Vss GND Vdd 5V VO Contrast RS Data Instruction set R W Read Write select E Signal Enable DO Data bus 4 and 8 bit D1 Data bus 4 and 8 bit D2 Data bus 4 and 8 bit D3 Data bus 4 and 8 bit D4 Data bus 8 bit D5 Data bus 8 bit D6 Data bus 8 bit D7 Data bus 8 bit A Optional backlight LED K Optional backlight LED 1 2 3 4 5 6 7 8 9 Ed Microcontroller Errata Atmel have released details of errors in the AT90S8535 microcontroller hardware design You should check out www atmel com and search for the 8535 for the full error list but the most important is the Secondary oscillator High Voltage fail
41. e but the 8535 has modest level of protection from attacks Generally invasive techniques are extremely difficult and as such usually only a dedicated laboratory and a person with sufficient expertise could perform this operation but the other two methods Software and Fault Generation are rather simple Atmel makes a special range of secure microcontrollers which have a SD pin The SD pin is actually short for Self Destruct and will destroy the chip if activated by an external security circuit Commercial products usually protect their IC s and mask the chip part number by covering the entire chip in a black resin Once this resin hardens it cannot be removed as it has a higher melting point than the maximum temperature of the chip it protects To prevent access from the underside these protected IC s are surface mount If you wish to protect your separate AT90S8535 chip don t try this with the ABC boards you can try to blow or destroy the MISO Port B 6 pin internally so that the program cannot be extracted without Invasive methods see above To destroy a pin internally use a 9V battery connected so that the positive lead connects to the chip s negative pin the negative lead of the battery is then connected to the pin to be blown Placing the 9V reverse bias onto a pin on the 8535 for approximately two seconds should damage the pin sufficiently but leave the rest of the chip intact Before attempting this it should
42. e PIC range may be bigger but many people are turned off using the chips as in many cases programs compiled on one PIC microcontroller would not run on another and the PIC language was too complex for the average user All Atmel AVR series chips run on a standard chip instruction set there are many languages available to the user which all compile to the standard hex or binary file for the chip and consequently programs written for one chip will run on any other chip from the Atmel range provided that both chips have sufficient memory and the correct features that the program requires Atmel chips are easy to program and do not need to be removed from the circuit for programming are cheap are reliable have many powerful features use low power and have incredible clock speeds some of over 17 million instructions per second In addition to the TINY 90S MEGA and other AVR series microcontrollers Atmel manufacture security and other embedded systems The Atmel website is located at www atmel com You can access Atmel s incredibly good customer service and ask any AVR related question you desire by sending an email to avr atmel com It has been my experience that Atmel always reply within three or so business days and always give an appropriate and informative reply Kd The separately available AT90S8535 The AT90S8535 microcontroller can also be bought separately without the board in a DIL dual in line package instead of the s
43. e g 1101xx1 These chips will come with pins labelled A followed by a number such as AO or A3 Connecting the external A pins to GND or VCC will cause the address bits to become 0 or 1 s preventing conflicts If your lC bus is very long an lC terminator will probably be required to extend the maximum length from master device to last slave device to 80cm The original schematic was designed by Detlef Queck and recreated by myself in the freeware Eagle schematic editor R1 ae sj LUE R3 Fa F 11 Cata J rr CI LT emma LL c T LT 7 4 t The January 2004 edition of Silicon Chip has a Picaxe 18X 4 Channel Datalogger project which has a more detailed explanation of the IC bus that cannot be added here due to copyright reasons NB Although the PC communication uses two wires it CANNOT be directly interfaced to the RS 485 or RS 232 serial communication protocols E Using the Watchdog The Atmel AVR chips come with a special hardware component called the Watchdog This is a special hardware timer that runs separately to the main program and once activated will reset the microcontroller if not reset within a specified number of cycles The microcontroller can behave strangely or freeze during power glitches or a dodgy loop could stop the program from working By enabling the Watchdog you can make the microcontroller automatically reset in the event of a lockup
44. e net and a small but excellent Quick Start manual is available free at http www smileymicros com Smiley Micros also offers a large C tutorial book but you will need to shell out some of your closely hoarded money for it Having said that it s worth it if you re totally clueless about the C language This book centres around the AVR Butterfly development board but most all of the knowledge can be modified to suit the ABC boards Learning C and using the WinAVR package is definitely not for the faint hearted It involves a lot of work to get started and the C language is both extremely powerful and complex If you wish to get started and program right away with a minimal learning curve try BASCOM AVR E Other programming methods software As mentioned the ABCEDIT program included on the HotChip Starter Pack CD is not the only program that can be used to program the AVR chips Apart from BASCOM and WinAVR another alternative is Atmel s the maker of the AT90S8535 chip own free programmer called AVR Studio This is available for download at http www atmel com and supports both the C and ASSEMBLER languages the latest version will integrate with GCC if you download the latter separately AVR Studio also supports serial programming of the AT chips but you will need to construct a serial programmer check out Silicon Chip s October 2002 article or purchase an Atmel board such as the STK500 or AVRISP for this to work Interes
45. ect and program file If you used BASIC to program click the Basic Compiler option button If you chose the more difficult Assembler click the Assembler option button Click the Add File button at the right to add any other files you need ASM BAS HEX or EE for your program Close the window Ok button and click Projects Save Click on Compiler Make to compile your program to machine code for the microcontroller If there are any errors you will need to edit your ASM or BAS file and re compile Once you have opened your project all compiling will be for that project regardless of any other open files To compile another project click Projects Open To download your program click Project Debug Download This brings up a complex window with many problems overlapping controls etc that would have benefited from a few minutes more work on its layout Click Load File in the File pane at the top right This should have your project s HEX file in the text box above Under the Parallel Port Base pane select your parallel port number 378h is parallel port 1 278h is parallel port 2 If you are using parallel port 3 or 4 click Othe yes know it should be Other but the label s wrong and type the port s HEX address in the text box below Under the Processor pane select AT9088535 second from the bottom from the drop down list box That done click Read Device Codes below the Chip drop down list box Underne
46. ed 5V regulator 1 Amp max This lowers and filters the 12V power from the plug pack or other power source The ST232 chip above the serial connector and the left of the memory socket is a Serial Transmitter Receiver IC This is identical to the MAX232 used in the ABCmini Below the AT90S8535 chip the small cylinder to the left marked X3 is the 37 768KHz crystal for the Real Time Clock as used on the ABCmini The miniature 3 pin IC marked with ABMY on my Hot Chip is a MAX809 or MCP120 in charge of the RESET pin identical to the ABCmini s This chip is located to the above right of the AT90S8535 chip and is small with 3 pins This is in charge of brown out low power protection When the chip first gets power this chip will hold the RESET pin low active until the voltage stabilizes This prevents incorrect chip behaviour if the voltage is low or a battery has just been applied Con 5 1 Con 5 2 Con 5 3 Con 5 4 LCD1 4 LCD1 3 LCD1 2 LCD1 1 MOSFET 3 or Con 4 7 J4 amp J7 MOSFET 4 or Con 4 8 J5 amp J8 Opto 1 or Con 4 1 J9 amp J13 Opto 2 or Con 4 2 J10 amp J14 Chip Select on optional Dataflash SPI bus and device programming SPI bus and device programming SPI bus and device programming RS485 BDIR J17 short 3 amp 4 LCD1 11 LCD1 10 LCD1 9 MOSFET 1 or Con 4 5 J1 amp J2 MOSFET 2 or Con 4 6 J3 amp J6 32 768kHz Crystal 32 768kHz Crystal RxD RS232 J17 short 7 amp 8 RS485 J17 short
47. eed to throw the chip away if the program is defective Fusebit Two named FSTRT controls power on speed of the AT90S8535 Chip Setting this to slow power up is useful when you do not have or don t want to use an external reset chip It is not necessary to change this on the ABC boards as an external reset chip is already on board As a historical note fuses got their name from early chips where certain options could be set by physically blowing connections off the chip s circuit Programs with blown fuses had to be thrown away to change the settings again Don t assume that activating the lockbits on your AVR will keep your code safe There are some unscrupulous persons in the world that can unlock your chip using some advanced methods some of which require the physical removal of the chip s protective plastic shell AVRfreaks net recommends removing the chip part number and programming SPI port pins usually by using side cutters and a strong glue to prevent access to the pins see forums before placing your chip into a commercial product There are three ways to break into a microprocessor Invasive where the chip is physically exposed and a microscope is used to bypass the lockbits Software where exploits are used to gain Documentation for the ABCmaxi and ABCmini Version 5 2 Page 20 access and Fault Generation where under voltage over voltage is used to bypass chip security The new MEGA series are the most secur
48. for about AU 3 per meter which is more than enough for a project and can be cut into several lengths Because the wires are all stuck together but can be pulled apart from either end this leads to a very neat connection and is very resistant to breakage IDE cables are cheaper AU 2 per meter and are completely grey in colour save for a single red line on the first wire for identification If your LCD uses a DIL dual inline configuration for it s connectors you can a block of DIL pin headers and attach a DIL socket to the end of some ribbon cable This method produces superior results to that of the SIL format described above Optional L 100n 5s Capacitor Connecting the 479056535 Microcontroller to the 241701 24172 LCD Documentation for the ABCmaxi and ABCmini Version 5 2 Page 24 Note The wiring shown the diagram is mandatory only in the ABCEDIT program supplied with the ABCmini Most other programs such as BASCOM allow the user to specify the ports and pins used E Wiring up an LCD to the ABCmaxi The ABCmaxi comes with an LCD connector on board This is a 14 pin box connector at the far left of the PCB The AT90S8535 drives LCDs in 4 bit mode the data is split into 2 4 bit nibbles and so does not need Data Lines DBO 3 to be connected Connector Diagram Pin Description Connects to on LCD GND GND VCC 5V 5V Port C 1 RS GND Contrast Port C 3 E Port C 2 R W Not Connected Not Connected
49. g a port that is connected directly to a 5V or GND rail as an output will use excessive currents and may kill the chip draining battery power and creating heat As a solution you could either leave it disconnected with its internal pull up enabled set the pin as an input or if power consumption is an issue use an external pull up resistor E Interfacing with the ABCmaxi s Opto Inputs The ABCmaxi board has four opto inputs on ports B2 amp 3 and ports D2 amp 3 These optocouplers allow the Maxi and another circuit to interface without any direct connections This can be useful in such applications as circuits powered by 240V mains where a power spike could ruin both circuits The opto coupler has four pins two of which go to an internal LED and two of which are a phototransistor When a voltage is applied to the LED side the transistor conducts sending the pin high To switch on the LED 12V must be applied to the EXT12V connector screw terminal 21 and the negative to the opto input E Wiring up an LCD to the ABCmini LCD screens generally have 14 pre drilled pads for wires to be soldered to backlit LCD screens have 16 the other two are for the led anode and cathode Wiring up these using separate wires looks unprofessional and the individual wires can break easily It is best to use either a 16 way ribbon cable or header pins and sockets if the LCD is to be plugged directly into a PCB Rainbow ribbon cable is available
50. g the ABC boards Incorrect ABCmini Cables Preparing the ABCmini for programming Preparing the ABCmaxi for programming The included software Using ABCedit on Windows XP Programming with ABCedit Programming with BASCOM Programming with WinAVR Other programming methods software Chapter 8 Appendix AT90S8535 Circuit Diagrams ABCmini Circuit Diagrams ABCmaxi Circuit Diagrams Circuit Diagrams for the ABCmini and ABCmaxi AT90S8535 Package Diagrams BASCOM Programming Flowchart ABCedit Programming Flowchart Standard LCD pin descriptions Microcontroller Errata What to do when you re out of Parallel Serial ports Author Info Bibliography References Disclaimer Documentation for the ABCmaxi and ABCmini Version 5 2 Page 4 CHAPTER 1 The ABC Range Ela ABC Kits available from Austrol Austrol sell both the ABCmini and ABCmaxi board in two different kit types A brief description is shown below Mini Starter Pack The Starter Kit is ideal for persons familiar to microcontrollers and or electronics It includes the programming serial cable the ABCmini board and the software CD The Starter Kit would be ideal for Electronics enthusiasts with a stock of electronics parts or for the prototyping of a commercial device This is the barebones of ABCmini kits all external devices must be created and attached by the user Maxi Starter Pack The Maxi starter kit contains the ABCmaxi board software CD ser
51. gh and then set the first column low Sequentially read the rows read row 1 then row 2 etc and get the inputs If any of the rows returns low that button is being pressed After the first column in scanned set it high again and send the second column low and repeat the process scanning each of the rows in turn After all the columns have been scanned you are ready to interpret the results This is fast and effective but can lead to ghost keys when several keys are pressed Documentation for the ABCmaxi and ABCmini Version 5 2 Page 31 um rr ak ak ak an an ro LLLlulld ok am 71 mil in mil bee mi lin am ae LA rap T rm mm mm mm Ca rm alas pq DE dh al mil ih zm al k al ba a he ake he lad ad i Pm Pm mn Pm I LLLILAXL4A d i ad Is ri ra ah ak ak all be eee dd T al li ri ri ah ak ah aa PI l Sees T a al a r6 ak ak dk ah ri E F mm F WM m F EF Sourced from Atmel application notes Here the key marked with an X is determined as pressed by the microcontroller when using the above method due to connections made while the other shaded keys are pushed The second method is slower than the first It requires sending the row and column ports high one after another to determine all the keys pressed with 100 accuracy but at a slower rate Remember that buttons and switches bounce after being pressed released giving multiple key press signals if a de
52. h the white connectors to your left you will notice the bottom left hole has a square shaped pad around it with the word Con4 stencilled below it The AT9088535 s board was specifically designed to be able to fit into a 40 pin IC socket for easy integration and removal from a circuit The Hot Chip Starter Pack comes with a small plastic resealable bag containing at least 40 lose pins for the user to solder to the microcontroller s board These pins look like miniature telescopes or syringes with a thick end which gradually changes over three steps into a needle like end To insert these pins in the board hold the board so that the AT90S8535 microcontroller is on top and insert the thin end of the pin into the hole the thickness of the end of the pins will prevent it from slipping through the hole completely The connector pads surrounding the holes on the board are double sided so you can solder from either side but it is practical to solder the underneath Using a GROUNDED soldering iron solder each pin to the board Be quick while applying the iron as too much heat can damage the microcontroller or the board s components Although it is possible to solder the pins you can insert them and plug the mini into a 40 pin socket and it should work perfectly provided that all the pins make a good connection If you choose this option no soldering is necessary and the pins will stay in place It might be a good idea to layer the bottom with a thin
53. he workaround uses the fact that rapidly pulsing the motor will cause it to rotate with a speed proportional to the frequency similar to a stepper motor PWM has the added benefit of using the motor s full torque at variable speeds unlike analogue voltages To connect a motor to a PWM output attach one wire to an output port or a transistor for more current and the other wire to the negative supply To operate the motor switch the port on with a PWM command You can also use PWM for a limited range of other devices PWM commands to LEDs will change the apparent brightness as the LED is cycled on and off too fast for the eye to detect but does not have enough time to build up to full brightness This has the same effect as supplying the LED with a lower voltage than required to shine at full brightness but does not change the supplied voltage which stays at 5v Most new mobile phones use pulse width modulation to make the backlit screen fade in and out and you can use PWM at varying frequencies to produce tones from a speaker Documentation for the ABCmaxi and ABCmini Version 5 2 Page 22 CHAPTER 5 Connecting to other Devices BA A Note about Power requirements Power Consumption When disconnected i e no devices connected to the I O ports the ABCmini consumes only a few milliamps typically less than 25ma of which about 17ma is powering the 8535 The onboard regulator for the ABCmini can only drive a few hundred milliamps
54. his line transmits O s and 1 s which equate to the line bouncing between 12V and 12V RS485 Basically works like this RS485 also uses 3 wires for data communication and like RS232 one is used for OV Ground Reference Where RS232 has a separate Tx wire and a separate Rx wire RS485 uses both wires for transmitting and both for receiving Documentation for the ABCmaxi and ABCmini Version 5 2 Page 16 When the wires are like this where a is positive this represents a logic 1 Wire a gt Wire b ree gt When the wires are like this and a is now negative this represents a logic 0 Wire a Sasani gt Wire b o gt The IC s that generate the RS485 signal continually change the polarity of the wires depending on whether a logic 1 or 0 is required The voltage difference between these wires is typically about 5V or less and must be less then 20V between the OV reference and either wire a or b When it is transmitting both of these wires form the Tx signal just the polarity of the wires changes to indicate the logic 1 or 0 When data is to be received the RS485 IC turns off it s internal transmitters and enables receivers inside the IC Now the polarity of the 2 wires forms the incoming O s and 1 s E Dual Communication protocols on the ABCmaxi Although the maxi can only receive one serial stream at a time like the standard RS 232 used with computers or the RS 485 protocol
55. hown and to an individual output on the ABC Each segment is also connected to a separate I O pin When programming you should make the ABC board send Digit 1 high or low depending on the display and light the segments you want Digit 1 to have then switch off Digit 1 and select Digit 2 Continue this all the way through the number of digits in the group lighting each digit for only a fraction of a second When each digit it shown or refreshed many times a second 15 30 refreshes per second a phenomenon called Persistence Of Vision causes the display to appear as if all of the digits are on with the correct numbers without any flickering the same system employed on TV and monitor screens If the refresh rate is too slow the display will flicker This method when used with 7 segment displays uses 8 I O pins for one digit one full port plus one I O pin for each additional digit The multiplexing method can be applied to dot matrix displays as well above With this method LED s are addressed individually Writing the letter A on this 4x4 dot matrix display would light the following LEDs ow 4 ow 2 ow 4 Led On Led Off In this method the Columns take on the same role as the Digit Pins in the 7 Segment Display A Column is held high while the rows to be lit are held low non lit rows are neutral Each column is turned on and its LEDs lit until all rows have been show in which case the cycle repeats for
56. i board is a simple affair Set the jumpers to enable the MOSFETs see the ABCmaxi circuits section and connect the motor as shown Part 4 Par C 5 Part B 0 Part B 1 100 Ohiris L 4 iH IRF S12 100 hires C 12V 47K For the ABCmini you will need to add the MOSFET circuitry as shown the Maxi has onboard MOSFETs The voltage applied to the MOSFET depends on the load and the MOSFET s maximum rating Most standard MOSFETs can drive up to 60V 6 Amps with no heatsink or a couple more amps with adequate sinking The Maxi s circuitry is thicker on the ground and VCC lines that run to the maxi to allow more current to flow but no heatsink is supplied on the board this suggests that the board cannot handle more than 6 amps at 12V STEFO STEP T STEP2 STEPS l l I I l l I porTcas P E i I PORT CS Sourced from Atmel application notes To drive the stepper motors you must turn on the MOSFETs in sequence after attaching it in the fashion shown above A backwards motion can be made by reversing the order of the sequences i e Step 4 Step 3 Step 2 etc E Chip to chip Interfacing You cannot interface IC s with different supply voltages directly as the logic levels will be different To overcome this problem a transistor and two resistors may be used to form a switch that activates the second IC s logic gate In this example the IC s run at 5v and 9v This circuit should onl
57. ial cable and programming parallel cable No add on boards are included you must purchase these separately or create your own Mini Educational Kit This educational kit is an excellent introduction to microcontrollers provided you have this document handy It contains the ABCmini board motherboard cables software CD and all six compatible add on boards Ela Add on boards from Austrol Austrol s add on boards are only compatible with the ABCmini when used in conjunction with the ABCmini Motherboard and connector cables ABCmini Motherboard This board allows you to plug in your ABCmini via the 40 pin socket It contains 8 4 bit connectors on board for you to interface with Austrol s other add on boards Documentation for the ABCmaxi and ABCmini Version 5 2 Page 5 Keypad Module Requires two I O connectors A 4x4 matrix of pushbuttons for user input Quad N Channel Logic Level MOSFET Although its name s a mouthful this allows you to interface he ABCmini to high voltage and high current devices Driven by a standard logic I O this will drive up to 33V at OA without an additional heatsink Quad Non Isolated Input Some devices use a higher logic level than 5V or you may wish to sense higher than logic level voltages on an I O This board will allow four inputs up to 24V
58. in roughly the right place near the power connector and is the only 3 pin IC could find This is in charge of brown out low power protection When the chip first gets power this chip will hold the RESET pin low active until the voltage stabilizes This prevents incorrect chip behaviour if the voltage is low or a battery has just been applied The rounded silver box with M8 000 stencilled on the top was an 8MHz crystal fed into XTAL and XTAL2 on the microcontroller from the ground 5 volt rail to provide the clock speed each one of the pulses given by the crystal will tell the microcontroller to execute an instruction Underneath there is a small round and silver component solders to the board This is a 32 768KHz miniature crystal This is connected to Port Group C Ports 6 and 7 and is used for the on board timing functions identified the long ish IC next to the serial port black connector as a MAX232 RS 232 serial Receiver Transmitter buffer in charge of converting the 5V RxD and TxD pins from the microcontroller into the correct voltages for the computer to understand and vice versa All ports groups A B C and D can sink a maximum of 20ma and can drive LED displays directly ChipDiagram Pin PinDescrption Port Group B Port 5 Also SPI Port Serial MOSI Port Group B Port 6 Also SPI Port Serial MISO Port Group B Port 7 Also SPI Port Clock SCK Reset activated by
59. integrated into circuits quickly with minimum effort All connections are sockets or screw terminals and most options are set using jumpers on the ABCmaxi board Wiring up a speaker for the audio port is easy find a 3 5mm mono plug and attach the terminals of an 8 ohm speaker to each of the plug s wires As it is only a single speaker it does not matter which wire goes to which terminal Documentation for the ABCmaxi and ABCmini Version 5 2 Page 10 Ela An alternative Serial connector In some cases circuits made will need to be frequently plugged into and thus unplugged from the computer s serial port Doing so with the onboard large IDC connectors is a hassle and can place excess stress on the cable pins causing them to wear out As a solution a stereo 2 5mm plug and Socket can be used To be on the safe side make sure the device is off when plugging and unplugging the cable as a stray voltage on a wrong pin can ruin the Atmel chip or your computer 25mm Plug and Socket Serial from ABCmini Serial to Computer or ABC maxi E Using ports C6 and C7 Port C6 and C7 are connected to the second external quartz crystal This crystal is a 32 768KHz miniature watch crystal that performs the onboard timer and clock functions To use the ports 6 and 7 of Port Group C you may need to physically remove the 32 768KHz crystal to free them up for use when designing applications that are port hungry Remember to use an anti static wristband
60. ith the parallel cable white port and the serial cable the black port on the Hot Chip s board listed as the Programmable Serial UART on the box is used for sending and receiving data from the computer The program G Day Mate etc has demonstrated two of the microcontrollers BASIC commands Print and Input This program is viewable in the Abcedit Source hello bas With my chip the program behaved differently to the source s code It kept looping instead of stopping via an endless loop StayHere goto Stayhere but assume this was altered in the default program so the user could test it a few times gt ABC EDITOR NDNAME PRJ Eie Edt COMMS Project Compier Options Micro Cortroders Libry Window Help i C Program FiesVbceda S ouce Adcdemol bat ADCDEMOL BAS ADC Demo Programme for the ABC Written by Bruce Heal Investment Technologies Pty Ltd You are FREE to distribute modify as you see fit ADC Demo for the ABC to 7 readadc w v 5 c a Bit High print CHANNEL v The Reading 18 t The Voltage is approx v next delag 2000 lA llow Time vend EOF LEDTEST BAS wmmsmmmmmmmuE Read Cursor Por The Industrial ABCedit Interface Some third party programmers and Atmel s AVR Studio free download from www atmel com use a serial programming method a special device is placed between the HotChip Atmel chip and the computer s serial port to translate commands in
61. lay between readings is not added BASCOM s keypad functions already have the necessary delays added so no extra wait commands are necessary EQ Driving 6 LEDs with 5 ports encountered an interesting LED chaser circuit on my net travels designed to give a KnightRider LED scanning effect with 6 LEDs but driven with only 5 ports This effect allows one LED to be on at one time and uses only two resistors Using the multiplex system of refreshing the LEDs multiple times per second the display can appear to have many LEDs on at the same time Modified irom hiipzthame wvsnadacnielegira Ier This was originally designed for the ATTiny22 microcontroller an Atmel AVR microcontroller with only 5 ports To drive this circuit setting PB4 high turns activates the first three LEDs and setting PB3 high the last three Setting PBO PB1 or PB2 low will turn on the LEDs To make the LEDs flash one after another in sequence the following ports have to be activated Forwards Backwards PBO PB1 PB2 PB3 PB4 PBO PB1 PB2 PB3 PB4 When both forwards and backwards sequences are programmed sans the first entry in the backwards sequence as this is identical to the last in the forwards sequence this will give the same effect as used on the classic KnightRider TV show Documentation for the ABCmaxi and ABCmini Version 5 2 Page 32 E Controlling 6 wire stepper motors Using a single stepper motor with the ABCmax
62. ne of its inputs either an external or internal pull up resistor must be used A pull up resistor maintains 5V at the input logic 1 until dissipated by a short to ground Logic 0 The standard value for an external pull up resistor is 100K Ohms although this may vary A typical pull up resistor connected with a pushbutton looks like this Bos onn PCE Pos Po4 PCJ PC P O1 Poo PDT POG POS PD4 POJ ursa E SNE When this pushbutton is not closed the port will read logic 1 or 5V Pushing in the button will make the port read logic 0 The logic can be reversed to form a pull down resistor by swapping the position of the pushbutton and resistors like this POJ PO This example will read logic O when not pushed or logic 1 when pushed The Atmel chips also include internal pull up resistors the value of which can vary between 35k to 120k ohms which can be enabled via software you will need to consult your programming software s manual and the PORT PIN and DDR section of this manual for the code to do this If you are using a sensor that changes resistance after a stimulus such as a CDS cell light sensitive resistor you can place this in the position of the pushbutton and connect to an A D port one of the port group A ports This will form a voltage divider whose voltage will vary as the resistance of the sensor changes in response to a stimulus When connecting sensors that use the Atmel chip s internal pull up
63. nstruction The most popular clock source for Microcontrollers is the quartz crystal as they are widely available accurate and cheap Each Microcontroller model has different specifications and so a suitable clock frequency must be applied accordingly Unlike other microcontrollers from other brands such as Microchip s extremely popular PIC range the clock frequency is not internally divided so an 8MHz frequency will execute 8 000 000 cycles almost all instructions take a single cycle to complete per second PIC micros divide by 2 or 4 so while one may use a 16MHz clock it is only executing the same 8 000 000 cycles per second Atmel microcontrollers have ports that are used to interface the microcontroller with external devices labelled as single alphabetical letters Larger micros have more ports and smaller ones like the ATTINY range can have only one Each port can have special features Port A on the 8535 is also an Analogue to Digital converter and has 8 individual pins In computers 8 bits equal a byte and so a port on a micro has eight bits either 1 or 0 labelled from 0 7 You can program a micro to switch individual port bits pins on or off or the entire port byte The AT90S8535 has 4 ports labelled PORTA through PORTD When programming the AVR chips you can set a bit high or low by addressing it such as PortA 2 1 in Bascom or set the entire port at one time by using a decimal 0 255 HEX 0 FF or binary 0 s and 1 s
64. nto a HEX file Unfortunately the program memory used for the HotChip boards can only be re written approximately 1000 times This may seem like a lot but experimenting developing can reach this limit quickly To make a program select File New from the menu bar at the top of the screen Call it what you want recommend placing it in a dedicated directory such as Abcedit Projects THISPROJECTNAME THISFILENAME Write your code into the editor and when you are done click File Save Note that the editor is NOT case sensitive i e TEST is the same as test and Test Commands and their descriptions are viewable from Help Basic Commands or Help Assembler Commands Next select Projects Open Open your program s directory such as Abcedit Projects THISPROJECTNAME and type the name that your want the program s project file to be called You will need to add a PRJ extension A dialog will appear asking Do you want to create etc Click Yes and a new larger window will appear unless you didn t add the PRJ a dialog will appear asking if you want to add the extension click Yes Click Browse Main File at the top of the screen and select the BAS or ASM file you wrote earlier Click Generate Hex File under Browse Main File at the right This will make a file name and path to appear in the text box above the button Make sure the text box below named DIR is the directory of your proj
65. ocument has been compiled from information gleamed from all over the net from books manuals fellow users forums and many other places To all who have helped me compile this document give you my sincere thanks as I m sure do the others who read this documentation hope this document will be of some use to someone and inspire others to make their own manuals or get started with the exciting world of AVR microcontrollers All the sources that used and can remember are listed below along with some places of interest If you have a URL you would like me to add or notice a source missing please email me at the address above URL S OURCE DESCRIPTION RA ee www invtech com au Investment Technologies Website designers of the ABC boards www avrfreaks net Very good forums on all AVR microcontrollers MEL M www atmel com Technical information on all Atmel AVR trie www groups yahoo com group ABCboardshotc Yahoo message board for the HotChip boards hip j FAFE www hw cz english docs rs485 rs485 html Information on the RS 485 Interface 9T O home wanadoo nl electro1 avr Information on multiplexing LEDs etc TT www cadsoftusa com Fantastic FREE schematic editor called ic Feat fete te te te www embedtronics com Advanced projects such as web servers and saowembesironiescom C Compact lash MES players frire r webring com hub ring avr Webring for all AVR related pages IMDISPEMSIELE projects cappels org
66. once a pre defined condition is met Interrupts can be used to execute a block of code after an interrupt is fired for example updating the time on a LCD screen each second using the timer interrupts Interrupt code is executed regardless of the current microcontroller state or program location even if the program is running an infinite loop To use interrupts in BASCOM you must place Enable Interrupts on a separate line as well as Enable Interrupt Name and On Interrupt Name Code Label for each of the interrupts you wish to activate Here s a BASCOM example of the Timer2 interrupt Documentation for the ABCmaxi and ABCmini Version 5 2 Page 14 Config Timer2 Timer ASYNC 1 Prescale 128 On TIMER2 Myisr ENABLE INTERRUPTS ENABLE TIMER2 DO Your program code goes here LOOP MYISR Code to be executed each second when using a 32 768KHz Crystal RETURN AVR microcontrollers contain several different interrupts which can be enabled or disabled individually Each hardware timer has several interrupts as does some pins and special subsystems serial byte received etc Because interrupts are hardware as opposed to software they are executed immediately When an interrupt actives known as firing the current program position is saved and the corresponding interrupt code run When the routine is finished the program continues from the point where it left off EQ Introduction to Digital Communication
67. ontrolling one or more slaves There can be a maximum total of 2 7 112 devices in 7 bit address Documentation for the ABCmaxi and ABCmini Version 5 2 Page 18 mode or 2 10 1024 with 10 bit addressing on each bus each with a unique address It is not recommended to connect more than 20 30 devices upon 10 feet then you need a repeater circuit A master device such as a microcontroller would send data down an I C bus to a slave device such as a port extender chip which would then react to the sent data The C bus has the advantage of being simple to implement only two wires between components and manufacturers produce many different types of low cost I C enabled chips I C chips will not work with the RS 232 standard serial communication protocol and vice versa Both lines SCK and SDA must be pulled high by two 4 7k resistors to the 5V rail Because there are several devices connected to a single bus you must address the device that you wish to communicate with Datasheets that come with the I C enabled chip will state the address as a 7 bit binary number for example 1011011 although 10 bit addressed devices exist Devices such as lC EEPROMS made by a single manufacturer will all have the same address leading to problems when several of the same chips are placed on the one single bus To overcome this there may be several address bits that are user selectable indicated by a letter instead of a digit in the address
68. ory socket Indicates not connected Indicates a jumpered connection In addition you should remove the PD2 as CTS jumper J18 located at the left of the board by itself when using the RS 485 protocol Activating the RS 485 communication will disable RS 232 serial communication and vice versa found a great article outlining the RS 485 communication method at http www hw cz english docs rs485 rs485 html which includes detailed technical information The following information was sent to me by Neil Wrightson via email RS485 is an electrical specification for a means of transmitting an asynchronous serial half duplex bi directional signal RS232 standard serial communication for simple bi directional data transfer uses 3 wires one for OV Ground Reference one for transmitting data and one for receiving data Because there is a separate transmit wire and a separate receive wire data can be traveling in each wire at the same time i e sending and receiving at the same time This is called Full Duplex The RS232C electrical specification basically states that the voltage that represents a logic 0 be greater then 3V and less then 15V The voltage that represents logic 1 must be less then 3V and greater then 15V Voltages between 3V and 3V are considered to be an illegal voltage A transmit on standard PC serial port DB9M Pin 3 is typically sitting at 12V whilst it is not transmitting data When it starts to transmit data t
69. ownloaded from the Investment Technology s website at www invtech com au Select COMMS Configure Leave the BAUD setting at it s default 9600 setting and change the COMPORT setting to the comport that the chip is plugged into When this is done Click OK and chose COMMS Open Comms Window from the menu bar Now you can attach the 9V connector to the two pin connector on the AT90S8535 s board All the connectors on the board are keyed i e are made in such a way as they cannot be plugged in upside down Click Run on the small window labelled COM TOOLS and the black rectangle will turn green to indicate that the microcontrollers program is being run Every AT90S8535 is pre programmed with the Hot Chip equivalent of the infamous Hello Word program for testing purposes This is tested before being sold so if it does not work you zapped it with static electricity the cables are not in correctly or someone sat on the Hot Chip s box If after ruling out all the possibilities listed above and there is no butt print on the box re check that the COMPORT setting in COMMS Configure is correct If all goes well the lines G Day Mate I am Your ABC and Whom am I talking to will have appeared in the ABC COMMS window This indicates that your Hot Chip is functioning correctly Out of interest you can type your name in the ABC COMMS window and press enter to view more of the message Programming of the AT90S8535 is performed w
70. ply Input GND OV Supply Input XTAL2 Clock Input XTAL1 Clock Input Port Group D Port O Also TxD for Serial Communications Port Group D Port 1 Also RxD for Serial Communications Port Group D Port 2 Also External Interrupt O Port Group D Port 3 Also External Interrupt 1 Port Group D Port 4 Port Group D Port 5 Port Group C Port 6 Real time Clock Crystal input Port Group C Port 7 Real time Clock Crystal output Port Group C Port 0 Port Group C Port 1 Port Group C Port 2 Port Group C Port 3 Port Group C Port 4 Port Group C Port 5 Port Group C Port 6 Port Group C Port 7 AVCC Supply for Analogue to Digital Converter AGND OV Supply for Analogue to Digital Converter AREF Reference Voltage for Analogue to Digital Converter Must be between 2V and AVCC Port Group A Port 7 Also an A D converter input port digital I O when ADC disabled Port Group A Port 6 Also an A D converter input port digital I O when ADC disabled Port Group A Port 5 Also an A D converter input port digital I O when ADC disabled Port Group A Port 4 Also an A D converter input port digital I O when ADC disabled Port Group A Port 3 Also an A D converter input port digital I O when ADC disabled OONDOABRWDN qe Go Ge Le de uus ES Port Group A Port 2 Also an A D converter input port digital I O when ADC disabled Port Group A Port 1 Also an A D converter input port digital I O when ADC disabled Port Gro
71. ps the l C bus uses a data address system and can send data both ways instead of the I C s master to slave transmission Port B bits 4 5 6 and 7 are reserved for the SPI interface if it is enabled TLC542 11 Input Serial A D Converter Above is an example of a SPI enabled IC the TLC542 A D converter chip This chip has 12 A D inputs 11 are external as the ANZ pins and the twelfth is connected internally to half the supply voltage as a battery status indicator The CS pin must be connected to ground while the CLK SI and SO pins are attached to the microcontroller s SPI port The channel is selected in the form of 4 address bits and the A D result is sent via the SO pin A D operations take 20us after the address is received the EOC end of conversion pin is pulled high when the conversion is complete Eta The I2C Communication Protocol The nter Integrated Circuit Bus is a popular method of data transmission to and from IC s in a circuit Designed by Phillips its original purpose was to create a simple interface between IC s in their TV set to reduce PCB complexity many manufacturers have since implemented the technology into everyday chips The lC bus also called the TWI or Two Wire Interface bus utilizes two wires that connect the serial clock SCK and serial data SDA pins on each l C enabled chip to each other Each lC chip can be in either master or slave mode although it is most common to have a single master device c
72. quare surface mount package used on the ABCmini board The separately bought chip is long with 20 pins on each side and does not have some of the extra features of the ABCmini like the onboard 32 768KHz crystal providing timing functions The separate AT90S8535 is available for about AU 20 and requires some extra components before it is fully operational see Appendix chapter near end of document The ABCmini circuit diagram shows how the parallel cable attaches to the 5 pin connector and how the 5 pin connector attaches to the ABCmini s microprocessor After checking the trusty Dick Smith Catalogue again found out the equivalent pins for the AT90S8535 DIL package listed later in this document This should enable you to program the DIL microcontroller using the ABCEDIT software have also pieced together the design for the serial port The MAX232 Transmitter Receiver microchip is available at electronics stores for approx AU 7 The pin equivalents and circuit diagrams are also located at the start of the Appendix chapter Note Because the 90S AVR range has been classed mature as of 2005 scheduled for production to cease sources for this chip may become difficult in the future However Atmel are now manufacturing equivalent chips with additional features as part of the new MEGA series Available for approximately the cost of the AT90S8535 the MEGA8535 is a drop in pin compatible replacement but with more features Documentation fo
73. r the ABCmaxi and ABCmini Version 5 2 Page 9 CHAPTER 3 Getting Started E Setting up the separate 8535 chip The Atmel AT90S8535 chip requires that you supply it with an adequate and regulated supply voltage of 5V To make the chip work you must add either a low voltage supply chip also known as a Brown out detector or voltage watchdog chip to the RESET pin or connect the RESET pin to VCC 5V For robustness and noise protection several other discreet components are also recommended see the Atmel design sheets on their website To make Port A function either as a digital I O or as an analogue input via the internal A D converter on the 8535 you must also set up the correct wires ACC and AREF to VCC 5V and AGND to GND Ground See the Pin Functions section for the pin numbers E Setting up the ABCmini The AT90S8535 microcontroller is sensitive to static electricity When handling the board hold it with all fingers at the edge away from the circuits and it is preferable to wear an anti static wristband available from most electronic hobby shops for about AU 24 The Mini requires a power source of 9 14V DC regulated and filtered on board to 5V Make sure your 9V battery is charged use a multimeter as the chip will not function correctly with a low power source The AT90S8535 microcontroller s board has a series of 40 holes 20 on either side running down the length of the board When holding the chip sideways wit
74. received money from friends and relatives and an ABCmaxi board from my parents This did not include the software or cables that the ABCmini included but this was due to it being only the standard pack not starter pack half priced at Dick Smith apparently they do not intend to sell it anymore in Australia and are getting rid of their stock Not to be defeated set out to understand its workings Later used the money had saved together with my 2004 birthday money to buy a second hand Compaq 700MHz laptop which am writing this on READ THIS ENTIRE DOCUMENTATION BEFORE STARTING AS SOME IMPORTANT INFORMATION IS DISCUSSED LATER IN THE TEXT THAT MAY DAMAGE YOUR BOARD IF NOT FOLLOWED This is mainly a hardware manual not a software manual Its primary purpose is to teach a novice user how to correctly set up the ABCmini ABCmaxi or separate AT9088535 microcontroller for programming and how to interface it to everyday components Some programming software is discussed but if you wish to learn a microcontroller programming language such as C Assembler or BASIC please consult your software s manual s Note when a is used in this document it indicates a computer program submenu Documentation for the ABCmaxi and ABCmini Version 5 2 Page 2 Contents Chapter 1 The ABC Range ABC kits available from Austrol Add on Boards from Austrol Chapter 2 Introduction to Microcontrollers What is the 8535 Micro
75. recommend that you read up on the binary and hex languages as they come in handy when writing programs To set the entire port you can use the Bascom code PortA amp Bxxxxxxxx for binary where the x s are replaced by a 0 or 1 PortA x for decimal where the x is replaced by a number between 0 and 255 or PortA amp Hxx where the x s are replaced by O F Each port can act as either an input or an output The AT90Sx chips use 5V TTL Transistor Transistor Logic technology for the ports and thus 5V on an input pin is a binary 1 or on and OV is a binary O or off Outputs are the same the port is 5V binary 1 when on and OV when off binary 0 Due to the microscopic size of the circuitry the outputs can only supply a tiny amount approx 20ma sink of current each Although this can drive a single LED directly with the addition of a current limiting resistor of 220 ohms most applications will need a transistor acting as a switch the Standard Transistors section or other such switching component to power higher current devices Light duty devices will require only a tiny standard transistor such as the BC548 but heavy duty applications such as high voltage or high current will need a large MOSFET transistor see MOSFET Transistors section or a standard transistor linked to a relay Documentation for the ABCmaxi and ABCmini Version 5 2 Page 8 Ea why Atmel Atmel have a huge range of microcontrollers Th
76. s are special transistors designed to switch large loads from a small current Many MOSFETs come in a TO 220 package similar to a voltage regulator Source Gate AH Drain UIEAC a5 a2unas A typical MOSFET It is a good idea to use a MOSFET to switch a high current item such as a globe or relay as the outputs of the AT90S8535 can only handle 20ma at 5V Jaycar and other electronics stores generally stock a range of MOSFETs with a maximum voltage ratings varying from 60 600V or more The onboard ABCmaxi MOSFETS do not get sufficiently hot to cause damage to themselves when running a small voltage and current up to 6 amps but will require adequate heat sinking if the load current is higher To use a MOSFET you will need a resistor to limit the gate voltage 100 Ohms is adequate for the AT90S8535 See the Circuit Diagrams for the ABCmini and ABCmaxi section for typical schematic to operate the transistor Please note that the diagram shown at the start of this section indicates the pin out for a typical MOSFET You should ALWAYS check the specific pin out for your MOSFET as this may differ Connecting a MOSFET incorrectly can have spectacular and damaging results especially with high current high voltage applications To make the MOSFET control a device that device s power supply should have its ground connected to the same ground as the supply that controls the gate In the ABCmaxi s case the 12V supply has its ground
77. stray electrical charges that have built up on the board or static electricity from your hands can destroy your ABCmaxi when plugged into the computer unless there is an earth bond between the PC and your Maxi s ground i e on one of its mounting holes The optimal way for this is an extra wire between your PC s case the inside conductive metal not the powdered metal or plastic case and the ground on the Maxi which should be plugged in BEFORE the parallel cable As a quick fix you can use the less prone to damage serial port as an earth bond by plugging in the serial cable into your computer and Maxi BEFORE the parallel cable If you choose this method make sure that you also unplug the serial cable last This also has the benefit of the ability to debug your programs Investment Technologies assume you earth the Maxi to a metal case which in turn would be connected to the mains earth but this is impractical for development so an earth bond to the computer is used found in an old Radio Shack catalogue we had lying around a special mains plug designed for anti static wristbands This consists of a plastic mains plug with all but the earth pins completely insulated made of nylon plastic and had a press button type connector at the front This is supposed to create a convenient and safe earth through the earth cable to your house s earth spike and you can connect your maxi to one of these plugs instead of your computer because the
78. t and a textbox called Text1 Private Sub Serial OnComm If Serial CommEvent comEvReceive Then Dim Buffer As Variant Buffer StrConv Serial Input vbUnicode Textl Text Buffer End If Bnd Sub The above code can be used to receive messages to send a message to the AT90S8535 chip use Serial Output Message amp VBCIL BasCom can successfully read messages sent from Visual Basic 6 via its serial in commands but have not been successful with the included ABCedit software Documentation for the ABCmaxi and ABCmini Version 5 2 Page 44 CHAPTER 8 Appendix a AT90S8535 Circuit Diagrams Basic 8535 Microcontroller Setup Hotchip Connector e GHD e L e L L e L L o L e x R L E BULL EN am z em L e L L Cr p L C n Looking at 25 EN pin male plug Note The 8MHz Crystal and the two 22pF capacitors should be mounted as close to the microcontroller as possible GM VOC Hc MU Es MC MC i CS UF WC SCE RESET Micro nirollar Port hl MC Pm un bOMOTC ME GND Wiring a 7 Wiring a LED Push bition g Wiring the external DataFlash Documentation for the ABCmaxi and ABCmini Version 5 2 Page 45 E ABCmini Circuit Diagrams po F ji SUE i Soak Pos zie cs imam q Pl ae BYP SoM T HI SE Fl AUDIO AMP 2 HPTMj HI HF C Investment Technologies GHz FRAPS _ it TF SOLDERING PINS BEE aa wien BE MOT LET Solver
79. tart bits and stop bits are customized by the device s software To prevent incorrect information corrupt data from being used by the receiving device a checksum could be added to the end of each block of data A checksum is a single byte the value of which is the sum of all the bytes sent in the previous block Once the checksum has been transferred the receiver can check to ensure the data it has received is valid if not it requests the data again ASCII is the global standard for data exchange and storage Because each byte of information can only store a binary number the ASCII standard is a table that converts numbers to their character equivalent You can find the ASCII table in hundreds of places on the Internet or in many computer related books E Using the RS 485 communication Protocol ABCmaxi There are two communication methods on the ABCmaxi RS 232 serial and RS 485 RS 232 was designed to be connected to your computer s serial port with a short piece of cable for debug or non outdoor applications Another communication protocol was added to the ABCmaxi called RS 485 which allows up to thirty two ABCmaxi s to communicate over a long distance with only two wires Upon emailing Investment Technologies maker of ABCmaxi and ABCmini they confirmed a transmission length of up to two kilometres This is the correct jumper settings for the RS 485 communication protocol LE These jumpers are located to the right of the mem
80. tingly Silicon Chip s programmer relies on an AT90S1200 chip to convert the serial port signals into a signal readable from the AVR This or Atmel s serial programmer can be used in circuit so you don t have to remove the ABCmini or AVR chip to program it The easiest and best programmer I believe on the net is the aforementioned BASCOM AVR LUE o ull De El Be Lap kp Jee Cagek orte je Peo ree Hep lH ril Sad i menu i or fab th RG e La ios L3 The AVR Studio 3 x Interface You can also receive serial transmissions from the ABCmini using Visual Basic 6 Add Microsoft Comm Control 6 0 from the components screen and call it Serial To open the port add the following code Sub OpenPort If Serial PortOpen True Then Serial PortOpen False With Serial GommPOort GertSoerting Trurp Serrtings Porc 1 Handshaking comRTS DTREnable True EOFEnable True RTSEnable True InBufferSize 1024 OutBufferSize 1024 NullDiscard True InputLen 0 InputMode comInputModeBinary Documentation for the ABCmaxi and ABCmini Version 5 2 Page 43 RThreshold 1 SThreshold 1 PortOpen True End With End Sub Call the OpenPort subroutine on Form Startup To close communications with the port the following code is necessary call it on Form Termination Sub ClosePort If Serial PortOpen True bThen Serial PortOpen False End Sub To get the received text add this even
81. to parallel signals This can be another alternate programming method if you cannot access a free parallel port Serial ISP in system programming devices can be purchased online or schematics downloaded for you to make yourself The software included with the HotChip boards ABCedit does not currently support the serial programming method and as such you will need to download a different programmer such as PonyProg B Using ABCedit on Windows XP Windows XP has a feature in it which prevents programs from directly accessing the serial and parallel ports This is supposed to lead to better security and stability but ultimately leads to a big hassle Programs that rely on the serial or parallel ports but do not use a driver usually do not work and may throw up a Privileged Instruction error There is a patch available called UserPort Documentation for the ABCmaxi and ABCmini Version 5 2 Page 39 Download and install the program from the Investment Technologies website see bibliography references at end of document E Programming with ABCedit Once a program has been written it is converted to Assembler if it is written in BASIC and then converted into machine code in HEX format ready to be programmed into the 8KB of FLASH memory Out of interest the 512 bytes of SRAM in the chip are used to hold variables and their values FLASH is not random access Programs written in Assembler are directly converted i
82. transmitted or copied without restriction but may NOT be modified for re distribution without the author s prior consent This document may be submitted to any hard copy or electronic database provided that a notification is sent to the author describing the action prior to submittal Documentation for the ABCmaxi and ABCmini Version 5 2 Page 53
83. up A Port 0 Also an A D converter input port digital I O when ADC disabled Ela Pin Functions and Circuit Details of the ABCmini If the instructions on using the software are mediocre programming terrible then the hardware aspect how to actually use the microcontroller in a circuit is shocking Or more accurately absent There is a program that will show the diagrams for various ABC chips run Dpcb exe from the ABCEDIT directory but the resulting diagram is cryptic at best Click Ok to the BAD FILE error if this pops up another software bug that should have been corrected it is designed to be run via a command line but ABCEDIT usually gives an incorrect path Click File Open and select ABCminct dpc from the ABCEDIT DPC directory This will show the diagrams for all the components on the AT908S8535 s boards and what they re connected to You will notice that there is a rectangle with numbered sticks from 1 to 40 are at the right of the diagram with the label CON4 40 PIN above it This is the pin outs of all the pins on the microcontroller s board Unfortunately while helpful to those who are experienced this is not great for novices as all the pins have shorthand labels to describe their functions such as AGND and AVCC Pins are counted from 1 to 40 pin 1 being the square hole on the board mentioned in the above section My electronics knowledge helped me with some of the labels GND being negative voltage
84. ure When the AT90S8535 microcontroller is driven at voltages above 4V the ABC boards run at 5V the secondary 32 768KHz oscillator may miscount This is unavoidable and cannot be corrected If you require a very accurate secondary timer use an external real time clock chip E What to do when you re out of Parallel Serial ports Some motherboards have up to 4 parallel and serial port connectors on the Motherboard but skimpy manufacturers usually only include one or two connectors on the case additional connectors are available at Computer shops and swap meets or you can scavenge one from an old obsolete computer s case An alternative is to use an expensive USB to Serial adaptor available for approximately AU 30 each Documentation for the ABCmaxi and ABCmini Version 5 2 Page 51 Ed Author Info A LOT of work has gone into the creation of this document Please feel free to email me with any comments questions abuse ideas on this document or the ABCmini ABCmaxi Hot Chip AT90S8535 Address all emails to dean camera ghotmail com without the quotes would love to hear from you would also like to hear about Stories Circuits Links to relevant Websites Technical Information Corrections Technical and Grammatical Anything else related to this document microcontrollers Please note that I am only able to provide support for the Bascom AVR s BASIC and AVR GCC C languages E Bibliography References This d
85. which then converts them back into readable characters In some cases such as the microcontrollers the binary will form a lot of nonsense words and strange characters because it is not text communication but machine code Machines do not use ASCII characters for programs and instructions rather the raw binary To ensure that both devices are in sync when receiving data a clock signal is used The clock line is a second wire that transmits pulses at a regular interval When a clock pulse is received the receiving device checks to see if the data line is high logic 1 or low logic 0 Below is an example of a piece of digital communication 8 bits The clock line is shown in red while the data is shown in blue j LJ LJ Tid L4 Le LJ LI LI LJ LI LI LJ Le Go qe p p 19 p p p Documentation for the ABCmaxi and ABCmini Version 5 2 Page 15 The above data line has transmitted the binary information 10110111 to the receiving device This is enough data to form a byte of 8 bits making the decimal equivalent of 183 ASCII character full stop period Communication with a clock signal is useful when the communication speed varies but if the speed is known a clock signal is unnecessary Devices communicating with a computer via serial link are configured to run at a preset transmission speed data is sent in bytes with a start bit high bit signalling the start of a byte transfer and a stop bit ending it The amount of s
86. wn below If connected incorrectly the fuse will blow but no power save for the tiny amount caused by the resistance of the fuse is wasted when connected correctly Fuse Diode From Battery To Regulator The ABCmaxi has been designed for mains power via plugpack and so has a reverse polarity protection diode installed An alterative method of reverse polarity protection exists using a MOSFET This has a very low voltage drop and is cheap to implement For the circuit do a search on Google E Sinking and Sourcing Current Documentation for the ABCmaxi and ABCmini Version 5 2 Page 23 A device is said to be sinking current when the current flows from the positive 5V line into it while sourcing current is the opposite current flows from the device to ground The 8535 can source only 3ma per pin but sink 20ma per pin Below is an example of a LED being powered by current that is sunk by the 8535 microcontroller s herocontraller Port When devices are powered in this manner they are activated by reverse logic where a low logic 0 signal will switch on the LED and a high will extinguish it The 8535 can sink more current 10ma per pin than it can source 3ma per pin Ea Unused port pins All unused ports on the AT90S8535 and other AVR microcontrollers should be connected to a defined logic state This could be directly to earth OV or VCC 5V but this is NOT recommended accidentally settin
87. xt This is the flat cable with a 9 pin D Sub connecter included in the Hot Chip Starter Pack Attach the D shaped end to your computer s serial port and the black rectangle end to the ABCmini this fits inside the black connector on the ABCmini While not absolutely necessary for programming the serial cable allows you to debug your programs if they use the serial data functions and should protect your board against damage if the parallel cable is inserted while the computer is on If you do not connect the serial cable static charges from the parallel port can fry the AT90S8535 if a common ground is not established first For more information on this read the ABCmaxi related Earth Bonding section The final cable to insert is the parallel cable This may be grey or black but is round with a 5 pin white connector at one end Plug this into the remaining slot on the ABCmini and into your computer s parallel port Do not use an automatic parallel port switcher my cannon scanner is in line with my printer and automatically switches between the two Install the software from the CD included with the Starter Pack but don t worry about the Read Me as said it is short poorly written and am explaining everything here E Preparing the ABCmaxi for programming If you have purchased an optional Atmel memory chip part AT45D041A 500kb to 4 megabytes plug it into the empty socket on the ABCmaxi board taking care to plug it in the way
88. y be used for CMOS IC s when the CMOS supply voltage is NOT 5v Documentation for the ABCmaxi and ABCmini Version 5 2 Page 33 Here the 10k resistor is used to pull up the 9v chip to a High state When logic 1 high is sent to the transistor from the 5v chip lowered to appropriate voltage via the 1k resistor it switches on shunting the 9v chip s input to low logic O In effect this is an inverter but this can by overcome by swapping the 9v chip s input and the 10k resistor to be ow the transistor s emitter gate with the resistor below the logic input To convert CMOS signals of over 9v to the TTL level of 5v the best way is using the versatile IC 4050 HEX Non Inverting Buffer The example below assumes a CMOS voltage of 10v but this can vary 10 Documentation for the ABCmaxi and ABCmini Version 5 2 Page 34 CHAPTER 6 Pin Functions and Circuit Details EQ Pin Functions of the separate 8535 Each port A B C and D on the 8535 can sink a maximum of 20ma Pin 1 on the microcontroller is identified by the small indentation at the top left hand side of the chip s package Chip Diagram Pin Pin Description Port Group B Port 0 Port Group B Port 1 Port Group B Port 2 Port Group B Port 3 Port Group B Port 4 Port Group B Port 5 Also SPI Port Serial MOSO Port Group B Port 6 Also SPI Port Serial MOSI Port Group B Port 7 Also SPI Port Clock SCK RESET Low signal GND to activate VCC 5V Sup

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