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Make: AVR Programming

1. If you re going to use a power on LED now s the time to plug it into the board to verify that you ve got power Wire it up as in Figure 2 7 Note that LEDs are polar ized and you ll need to make sure that the positive side is connected to VCC and the negative to ground You can recognize the negative side of an LED by its shorter pin think of it as the minus side having something subtracted from its length or by the slight flat spot on the flange of round LEDs or by the larger structure inside the LED itself Connect the resistor up to the negative pin Plug your USB programmer into your computer If the LED glows the power supply is ready to go If not and you re using a programmer like the USBTiny you may have to install a jumper across two pins to enable the power supply passthrough See the instructions that came with your programmer for how to make the programmer supply power to the AVR If this still isn t working double check your 6 pin con nector again After you ve gotten the power on LED light working you know for sure that you re getting power on the breadboard s supply rails Chapter 2 Programming AVRs 31 Getting Started Blinking LEDs 32 eee sosoo sosoo sosoo sosoo sosoo sosoo n n n n eee s s so eee sosoo sosoo sosoo n n n n eee COCO OEE HHEHHHHEHHHEEHEHHHEEE COCO OOO EET E HHH HHHHE HEE HED ey OO COCR evsssvwswusevceoesvswsssstsesicescseecicnitnistsiistttitititiititi
2. you deleted a semicolon Learning to deal with the error messages is an important part of coding Make AVR Programming Getting Started Blinking LEDs If you deleted a semicolon as suggested you ll probably see an error like blinkLED c In function main blinkLED c 22 5 error called object _delay_ms 1 0e 3 is not a function The compiler is telling you that something went wrong around line 22 in the code specifically something that starts at line 22 column 5 It doesn t know there s a missing semicolon but it gets you in the right neighborhood This is where you have to do a little detective work The meaning of the error is that lines that look like something without a semicolon at the end are supposed to be function def initions but in this case it s not The compiler can t know that you meant use a function rather than define one if you don t add that semicolon on the end It could be worse Sometimes there will be a string of many errors all in a row Don t give up It s not necessarily the case that you made many errors but maybe the first one caused a bunch of follow on problems to arise If the compiler gives you multiple errors it s often a good idea to start fixing the first one by line number and then see if that resolves the rest Anyway fix up that semicolon and reflash your valid code with a make flash Notice what a successful flashing looks like Heck if you re feeling nerdy scroll ba
3. Learning to Write Software for Hardware Elliot Williams Hardware Programming Make AVR Programming If you ve been using an Arduino in your projects and you need more speed real time response to external events or the ability to multitask it s time for you to take the next step Learn to use the full power of the AVR microcontrollers that lie at the heart of the wildly popular Arduino hardware This book will get you using Atmel s AVR series microcontrollers to their fullest Discover how the AVR s built in hardware peripherals can help you solve your project design problems Take advantage of all that the AVRs have to offer write your own programs in C and work directly with the hardware rather than abstracting it away But AVR Programming is about more than just programming microcontrollers This project oriented book will also show you how to build circuits that interface with the outside world Before long you ll be applying what you ve learned and experimenting with new ideas In Make AVR Programming you ll learn microcontroller basics but you ll also move on to intermediate and advanced projects Respond instantly to as many external events as your AVR has pins Build an inexpensive footstep detector Build circuitry to drive DC and stepper motors as well as other demanding loads Make your projects talk by storing voice sample data in the AVR s non volatile memory Learn to speak SPI and I2C If you ve
4. Make AVR Program ming and related trade dress are trademarks of Maker Media Inc Many of the designations used by manufacturers and sellers to distinguish their products are claimed as trademarks Where those designations appear in this book and Maker Media Inc was aware of a trademark claim the designations have been printed in caps or initial caps While every precaution has been taken in the preparation of this book the publisher and authors assume no responsibility for errors or omissions or for damages resulting from the use of the information contained herein ISBN 978 1 449 35578 4 LSI PrefaGG cesssuhe os RAReEQUERRORCEQFERE E RA ores XI PartI The Basics 1 Introduction sio veo woe s v g apEFSE RS 3 What Is a Microcontroller The Big Picture cece eee eee 3 A Computer ona Chips see er eR ERRARE ERAS IRAK 3 Buta Very Small Computer 0 cc cece eee e eee erences 4 What Can Microcontrollers Do sees 5 Hardware The Big Picture 0 eee c cece eee eee eee n een eees 5 The Core Processor Memory and I O 0 cece cece cece eeeee 8 Peripherals Making Your Life Easier 0 cece eee ee ee ees 9 e Programming AVRS ccccccccccssseeeese 13 Programming the AVR uocrsio tek epDPR EROR POR EEUU ECRE 13 TOO EAM sis Losve Lo E ENT DA AN a Satan RN 14 The Software Toolchain ssssssesessresenssssssserererssses 16 LIMUN Setups sess esocee ee v
5. hardware because it s useful so getting further away from it won t help My friend Ash once described working with the Arduino environment as being like knitting in boxing gloves don t think that the built in hardware timer modules are something to be ab stracted away from believe the timers should be understood thoroughly enough to be abused to create a small AM radio transmitter that can play the Mario theme song within a room using nothing more than a wire or your finger as an antenna in Chapter 9 And believe that this code should fit in under 500 bytes of program memory More seriously many of the hardware peripherals inside the AVR are common to most microcontrollers from the prehistoric 8051 orthe tiniest PICor ATtiny chips through the MSP430s and the ATmegas to the mighty XMega and ARM chips These hardware peripherals have been developed and honed over 40 years of microcontroller design development and they re not going away any time soon because they have been designed to be helpful to getting your project realized The microcontroller hardware has been designed by very clever engineers to solve your problems My goalin writing this book is to show you how common problems are solved You need to learn the hardware and apply the hardware to love the hardware Although every microcontroller design implements things a little bit differently once you ve seen it here it will make sense there Every microcontroller
6. so you can recode around it Debug There are many tricks for figuring out what s going wrong with your code from lighting up status LEDs to transferring vari able data information over the serial line to your desktop computer to stepping through the code with a debugger Programming the AVR What s Really Going On AVR microcontrollers are able to write into their own flash program memory space All of the ATmega ser ies microcontrollers are set up so that when you reset them they start listening for data on the SPI lines and with the right instructions can program themselves A flash programmer works by grounding the RESET line which halts the CPU and signals the AVR to start listening on the SPI bus The programmer then trans mits programming instructions over the SPI bus Af ter each instruction or section of code the AVR writes the received data to flash memory Some of the tiny AVR chips flash the data to program memory after every few bytes which can be slow Larger and newer chips store the incoming data in a temporary page memory and then write it all at once which is much much faster After the programming is complete you can read the data back out of the AVR s flash program memory to verify again that its correct The v flag for AVRDUDE does this for you For a deep read on programming the AVR chips for instance if you want to implement your own flash programmer or write your own bootloader once yo
7. The MAKE audience continues to be a growing culture and community that believes in bettering ourselves our environment our educational system our entire world This is much more than an audience it s a worldwide movement that Make is leading we call it the Maker Movement For more information about MAKE visit us online Preface xvii xviii MAKE magazine http makezine com magazine Maker Faire http makerfaire com Makezine com http makezine com Maker Shed http makershed com We have a web page for this book where we list errata examples and any addi tional information You can access this page at http oreil ly avr programming To comment or ask technical questions about this book send email to bookquestions oreilly com Acknowledgments would like to thank the members of HacDC and especially those who were sub jected to my first couple of classes teaching microcontroller programming I ve learned as much from you all as you have from me And you re all the inspiration for this book in the first place Special thanks go out to Gareth Branwyn and Alberto Gaitan for pushing me into writing this crazy thing You are truly overlords and enablers Respect To anyone who has contributed to the greater hive mind that is the global hacker Maker community if you ve put anything microcontroller related out there you ve probably contributed to this book in a six degrees of separation sort of way hope
8. a light on and off Getting from typed letters on a computer screen to a working piece of electronic machinery requires a chain of tools called predictably a toolchain Toolchain overview 1 Write your source code in an editor 2 Turn your source code into machine code with a compiler and associated soft ware tools 3 Using uploader software on your big computer and a hardware flash program mer send the machine code to your target AVR chip which stores the instruc tions in its nonvolatile flash memory 4 Assoonas the flash programmer is done the AVR chip resets and starts running your code Figure 2 1 sketches out the main steps in AVR firmware development along with which tools you ll use for each step The first step in your toolchain is going to be a text editor or whatever you re most comfortable writing code in For the Linux folks out there gedit is quite nice On Windows platforms you ll probably find the editor that comes with WinAVR Pro grammer s Notepad will work pretty well but prefer the freeware Notepad Many Mac coders swear by TextMate If you ve already got a favorite code editor by all meansfeel free to use it Nice features to look for include syntax highlighting automatic formatting and indenting parenthesis matching and maybe even code folding Put your copy of Microsoft Word away that s not what we re looking for here 14 Make AVR Programming Programming the AVR Editor E Com
9. breadboard and you re going to use the Arduino as the hardware programmer thanks to example code that converts the Arduino into an Arduino In System Programmer ISP You can do this either from within the Arduino software IDE or you can use an editor and the avr gcc toolchain independently Wiring your Arduino as a flash programmer The first step toward using your Arduino as a flash programmer is hooking it up to your breadboard The essential six connections are power ground RESET PC6 SCK Chapter 2 Programming AVRs 25 AVR and the Arduino 26 PB5 MISO PB4 and MOSI PB3 You ll find these pin names in Figure 2 5 on page 2 of the AVR datasheet or you can also just refer to Figure 2 3 Made with 9 Fritzing org Figure 2 3 Arduino as flash programmer The single red LED hooked up to pin PBO on the target AVR is the LED in question if you re uploading this chapter s bLinkLED code The three optional colored LEDs hooked up to the Arduino are status lights Green will pulse while the ArduinolSP is waiting for input yellow will light when it s trans ferring code to the AVR and red will light if there s an error You can leave these out but they make everything look so professional no Resistor values for the LEDs aren t too critical but something over 200 ohms is a good idea for normal LEDs which commonly have around a 1 7 V threshold voltage and are rated for around 20 milliamps 5 V 1 7 V 220 ohms 15 m
10. chips if you need to xi Xii picked the C language because it s pretty much the standard for programming microcontrollers It s just at the right point for my taste in terms of being abstract enough to read but low level enough that turning an individual bit on or off doesn t require subclassing or overriding anything Your C code will compile down to something that is nearly as efficient as the best written assembler but it s a heck of alot easier to maintain There s also a ton of code examples out there on the Web for you to look at and learn from That said if you really want a good feel for how the hardware works teach yourself AVR assembler when you re done with this book On the other hand this book is really a book about programming and using mi crocontrollers in general Though the particular naming conventions and some of the implementation details are different across different brands of microcontrol lers the basic principles will be the same More on this in just a minute Software Type or Hardware Type In a class on programming microcontrollers that taught at my local hackerspace discovered that the students would identify largely as either hardware types or software types Some people coded JavaScript for web applications all day while others worked in electrical and machine shops One guy had never seen a for loop and another didn t know that the red wire is the positive side of a battery pack Everyone ha
11. command line flags and arguments that you can use You can read up on the most useful ones in AVRDUDE Options on page 35 If you don t get AVRDUDE running from the command line you re going to need to make sure that it s installed and that your OS knows the correct path to find it If you re on Windows the easiest way is probably to uninstall WinAVR and reinstall allowing it to set up the PATH variable for you this time Linux and Mac people should not have this issue pd Drivers and Windows If you re running Windows you may not automatically have the correct drivers for your pro grammer installed This is notably the case with Windows Vista and Windows 7 and the USBTiny and USBasp type programmers If you get a warning message like usbtiny device not found it s very likely that your drivers aren t set up right You should probably follow whatever instructions your programmer comes with For me had to download a newer libusb from LadyAda website install it and then do a manual install of the USBTiny drivers through the Device Manager This step is no fun but you only have to do it once Now let s try to talk to the programmer directly Type something like avrdude p m168p c usbtiny to interrogate the chip only substitute your programmer in place ofthe usbtiny and optionally adda serial port and baud rate If allis hooked up well it will respond with something about the chip s signature and fuses and say OK Success
12. looks something like this avrdude AVR device initialized and ready to accept instructions Reading dHHEBHBHHHHHEHBHHHHHHEHHEHHHHHHHHHEHHHHHHHHHHHHHHHHHHHHE 100 0 01s avrdude Device signature 0x1e9406 avrdude safemode Fuses OK avrdude done Thank you Chapter 2 Programming AVRs 35 Getting Started Blinking LEDs AVRDUDE Options Whoa That s a lot of choices Let s look at a few of the ones that we ll use C programmer Here you specify the type of flash programmer that you re using Many serial programmers in cluding the ArduinolSP use the generic av risp type not the arduino type which pro grams the Arduino itself There are also config urations for both usbasp and usbtiny pro grammers If you d like to see the full list type avrdude c p partno Here you specify the type of AVR chip that you re programming for In our case m168 is an AT mega168 chip or m168p if you ve got that version P port If you re not using a native USB programmer for instance if you re using an ArduinolSP you ll need to know which serial port the programmer is connected to See Common AVRDUDE Con figurations on page 38for details On Windows it s usually something like COM3 on Linux and Mac OS it s in the dev tty lineup b baud This sets the baud rate if you re using a serial programmer You ll have to know what speed your programmer wants or use trial and error AVRDUDE e
13. luxury that fewer and fewer of us have On the other hand if you d like to go this route search the Web for a DAPA Direct AVR Parallel Access cable Many of the schematics will include safety resistors feel free to ignore them unless you re hooking up your AVR to voltages higher than 15 V If you ve got an unused parallel printer cable lying around you ve got your first programmer Atmel AVRISP mkll Atmel s current official USB in system programmer the AVRISP mkll is a very nice programmer that s capable of programming the whole AVR line including the newest XMega devices It s a bit more expensive than other programmers but it s rock solid and is quite a bargain all in all USBTiny and USBasp These two USB based AVR programmers have super simple hardware designs with open source firmware You can make one yourself although you will iron 28 Make AVR Programming Getting Started Blinking LEDs ically have to find a way to flash the firmware into the AVR in the programmer an Arduino ISP is perfect for this You can also find these designs for sale all over l ve got a USBasp based programmer that bought for 5 online and it s just fine Both ofthese designs have a jumper that allows you to power your breadboard off of your computer s USB port which is handy for most applica tions in this book LadyAda s USBTinylSP This is an improved version of the USBTiny with input and output buffering I ve used one of these fo
14. offer to change your PATH variable so that all of the binary files importantly make avrdude and avr gcc are available without typing the full pathnames in Be sure that you allow this Mac Setup AVR CrossPack is the way to go for Mac It includes all the compile tools AVRDUDE and more It s kept up to date and should just work Arduino Setup As a fourth option the Arduino IDE is available for all three OS platforms Heck most of you will have it installed already If you ve got Arduino up and running there aresome modifications you can maketo turn your Arduino IDE into a working generic AVR C language environment See AVR and the Arduino on page 20 and in particular Writing C in the Arduino IDE on page 24 for details Make AVR Programming The Software Toolchain If you d like to use your Arduino as a hardware flash programmer but don t plan to use the Arduino IDE you can do that too In addition to the Arduino install install the software toolchain for your OS Make and Makefiles The C programming language lets you split up one big program or task into a bunch of individual functions and lets you keep collections of functions together in their own files for easier maintenance and portability That way if you want to frequently reuse some serial port input output functions for instance all you have to do is include the serial library code files by name in your main code and then tell the compiler where to fin
15. should be typed literally by the user Constant width italic Shows text that should be replaced with user supplied values or by values determined by context pd This icon signifies a tip suggestion or general note xvi This icon indicates a warning or caution Using Code Examples Supplemental material code examples exercises etc is available for download at https github com hexagon5un AVR Programming This book is here to help you get your job done In general you may use the code in this book in your programs and documentation You do not need to contact us for permission unless you re reproducing a significant portion of the code For ex ample writing a program that uses several chunks of code from this book does not require permission Selling or distributing a CD ROM of examples from MAKE books does require permission Answering a question by citing this book and quoting example code does not require permission Incorporating a significant amount of Make AVR Programming example code from this book into your product s documentation does require permission We appreciate but do not require attribution An attribution usually includes the title author publisher and ISBN For example Make AVR Programming by Elliot Williams MAKE Copyright 2014 Elliot Williams 978 1 4493 5578 4 If you feel your use of code examples falls outside fair use or the permission given here feel free to contact u
16. to Here l m using a 25LC256 32K SPI EEPROM chip For the Motors and H Bridge Chapters e A small DC motor 3 12 V is good got mine from a racecar toy e MOSFETs for building an H Bridge use two IRF9530s and two IRF530s e SN7544100rL293D motor driver chip instead of or in addition to the MOSFETs e A stepper motor and a power supply to drive it e Random switch like devices relays SSRs Darlington transistors TIP120 etc Random DC powered devices like LED lamps or pumps or fans or solenoids or kids toys or e A5V relay Deluxe and Frills A standalone voltmeter e An amplified speaker computer speakers are ideal A soldering iron and some solder e A prototype board for soldering up your circuits permanently Preface XV e Extras of everything in the first list so that you can create permanent versions of each chapter s project that you like Nothing beats having a bunch of sou venirs around to show off what you ve learned and to go back to and modify later on Conventions Used in This Book The following typographical conventions are used in this book Italic Indicates new terms URLs email addresses filenames and file extensions Constant width Used for program listings as well as within paragraphs to refer to program elements such as variable or function names databases data types environ ment variables statements and keywords Constant width bold Shows commands or other text that
17. to get into here don t recommend it when you re just starting out Anyway once you can write and edit code you need to compile it for the AVR turning your human readable C code into machine code for the AVR The compiler we re using avr gcc is the AVR specific version of the popular open source com piler GCC In fact would argue that the support from Atmel for avr gcc and an open source toolchain is the main reason for the chip s amazing success in the hacker community Chapter 2 Programming AVRs 15 The Software Toolchain 16 In addition to the compiler you ll need a few more software tools from the avr gcc suite to go from source code to machine code that s ready for uploading A script called a makefile is commonly used to automate all of the repetitive inter mediate bits of the process See Make and Makefiles on page 19 if you want to learn a little more about what s going on with the makefiles but don t sweat it if it s too much info you can do everything you need to by simply editing a few lines and l Il walk you through that Once you ve compiled your C code into machine code in the right format it s time to send the machine code over to the chip and write it into nonvolatile flash mem ory The flash programmeris a piece of hardware that sits in between your computer and the target AVR microcontroller The AVR microcontrollers when put into pro gramming mode listen over their serial peripheral interface
18. you enjoy it This book couldn t have been made without the help of the tremendous folks at O Reilly and Maker Media Patrick DiJusto edited the text with a fine tooth comb and provided much helpful feedback Brian Jepson Shawn Wallace and Dale Dougherty provided high level direction Kara Ebrahim helped pull it all together Also much thanks to Eric Weddington for his technical review Writing a book is a team effort and thank you all Finally my wife Christina has my endless gratitude for letting me see this long project through Hab dich lieb Schatz Make AVR Programming p Programming AVRs Hello World In this chapter you ll get set up with everything you need for coding compiling and flashing your programs into the bare silicon of the AVR chips that are sitting on your desk right now To do so you re going to need some hardware a flash programmer and some software a code editor C compiler and the program that ll communicate with the hardware flash programmer Finally you ll need to hook up some wires from the programmer to the AVR chip and get set up with a power supply In this process there are a ot of different approaches that will get you to the top of the same mountain Ultimately the different approaches are all basically the same at some abstract level but we ll step through some details of a few of the most popular options to make things clearer On the hardware side most of the flash programm
19. SPI bus for incoming data to flash into program memory The flash programmer s job is to relay the compiled machine code to the target AVR over the SPI bus There are tons of flash programmers available and l ve listed some of my favorites in Flash Programmers Have Known and Loved on page 28 Alotof you will have an Arduino sitting around If so it turns out to be fantastically easy to turn that Arduino temporarily into an AVR programmer I ll walk you through the steps to do so and how to wire it up in AVR and the Arduino on page 20 So if you don t have a dedicated hardware SPI programmer just yet l Il get you up and running with an Arduino Now stepping backto your main computer you ll need to run software that feeds the compiled machine code to the flash programmer Far and away the most pop ular software uploader is AVRDUDE which is available for all platforms and sup ports a wide variety of programmers How wide So wide that almost any way that youcanthinkof communicating in SPI with the target AVR will work with AVRDUDE from a few wires hooked up to your parallel port to dedicated USB programmers with their own AVR microcontroller brains The Software Toolchain The main feature of the style of software development that we ll use in this book is cross platform compatibility That is if you re used to the whole workflow of writing code and compiling it on a Mac you ll have the same tools available for you on Wind
20. a YeDp I ERE UPUEPEPPDI POE PS 18 Windows Setup er oesexser Rer Or C RCE TO CUR EE A 18 Mac SOT Du ua nonse Ir o e ee EE ea UU ARIES IN SORS RE SI 3E 18 Arduino Setup iis cides e ear EP PY RR DC ORI YER eR 18 Make and Makefiles oreet cheer E ee ees 19 AVRand the Arduino cc ccc cece ccc cence cece e aa 20 Ardulno Pros seks cee des Coke week aoa X ERG ada E RS IS 20 Arduino CONS esris irder E PUE pO PRDUPRRRQWY Aaa Ada 20 The Arduino Is an AVR 6 eee cece eee creer ee 23 The Arduino Is an AVR Programmer ee cee eee ee eee eee 25 Other Hardware Programmers 0 cece eee e cece e eee eeeeneees 28 Flash Programmers Have Known and Loved 28 Getting Started Blinking LEDs 0 cece eee eeeeeeeeeeee 29 HOOKUP iis PEE 30 S PACA STS cis C E 33 AVBDUDE c csseries view cenees bs view oov e Savion Nee Fee O4 Enel 35 Configuring Your Makefile cece eee e cence een eees 38 dr m P 40 TroubleshoOEl Dp cessoc ee ees prep Ox eR ha FUP UE SR RE E ad 40 Digital Output ooo eer rr ARR EREReIT 43 BlinkLEDRedx ucc Ss echec Et cer bts enc etes Fotos 44 The Structure of AVRC Code epe rerrer ite repetens 45 Hardware Registers cece cece cece e cece cece n hehehe 46 blinkLED SUMMARY ss ccscereinieeiscosesedaas Sen ie ass ener 49 POUEOULieedes eu cease so DER V Ed N SUAE 49 Building the CIEGUIE es oem oor Re xr
21. accessibility But that doesn t mean that there s any reason to let your Arduino gather dust in fact the Arduino plat form can be a great generic AVR playground once you know how to ab use it Arduino Pros One very real advantage of the Arduino hardware setup is that the chip comes pre flashed with a bootloader which is code that enables the chip to communicate with your computer over the serial line in order to flash program itself This means that you can do away with the requirement for an external bit of hardware to flash the chip there s a tiny bit of bootloader code already running in your Arduino that ll flash the chip for you The second highlight of the Arduino package is that it comes with a built in USB to serial converter so you don t have to buy a separate one just yet personally get a lot of mileage out of my USB Serial cable and you will too if you want to play around with freestanding microcontrollers GPS units old terminals hacked WiFi routers and other devices If you re going to get serious about embedded elec tronics hacking you re going to want a standalone USB Serial adapter eventually but it s sweet that the Arduino lets you get away without buying one for the time being And finally although it s not such a big deal the Arduino is powered by your com puter s USB power supply This is handy if you re developing code on your laptop in a park or on a plane You don t need to find a wall plug for you
22. ade eir teres ros 414 Storing in Memoty escrocii ere epe eee n eee 414 Reading from Memory 20 eee e eee cece cree ee eneenenes 419 Saving and Loading EEPROM ccceecececeeeeneenees 422 viii Make AVR Programming 20 Organizing Data in EEPROM esses 423 Project Vigen re Cipher Encoder Decoder ee ees 426 Conclusion Parting Words and Encouragement 06060606006000000000600600000000000000000000060000000600000999 437 Learning AVR The Missing Chapters ceeeeee ee ee ees 437 The Watchdog lel dde ree ete ces mm en me ees 437 Power SavibUs coi rar risata eR tbe eI dS Re ERU 438 Crystals and Alternate Clock Sources 0 eee seen eee eees 438 Bootloadets ci xetpety eed nR E CIEN CQREREOIEUP QUAS 438 Analog Comparata e acer teo Et tier t oe amne 439 Debtugditig c seseycexoenderpxUpxochueorRUer cbe CU RUE DROPS 439 Put This Book Down and Buildl eere 440 Intlex cosas Ee ER E NENE ERPINEXE ER PAN RE REP V T Table of Contents ix Microcontroller projects are ubiquitous in the hobbyist hacker Maker world and with good reason Microcontrollers stand directly in the middle ground between the hardware world of buttons motors and lights and the software world of al gorithms connectivity and infinite possibility Microcontrollers are part computer and part electrical component They can also be the metaphorical glue between the real world an
23. ation and anything else where timing is key BAUD This is the baud rate that you re going to use for computer to AVR serial com munications and 9 600 baud is a good conservative default MAIN This entry is just the name of the program that you re compiling and flashing the code that contains the main routine l ve filled this in for you in the book s projects but if you want to start a new project from scratch but reuse this makefile you ll need to change the MAIN LOCAL SOURCE Here you have the chance to list any other c files that your main code section needs to run Again l ve filled these in for the book s projects but mention it here in case you d like to see how to include multiple files in your compilation EXTRA SOURCE DIR and EXTRA SOURCE FILES This is an option to include code that lives in another directory or folder some where on your system We ll use this a lot for including my USART h standard serial library PROGRAMMER TYPE The two programmer options are for AVRDUDE along with information about what chip we re programming from MCU Here you enter the type of flash programmer that you re using and the makefile passes it to AVRDUDE using the c option If you re using a USBTiny or USBasp for instance you enter that here If you re using the Arduino as a flash programmer enter avrisp PROGRAMMER ARGS The other programmer option is for any of the other necessary AVRDUDE options If you re using a USBT
24. bier a PER meos 50 Pretty Patterns The POV Toy Code cece ccc cece eeeeees 54 Expernme ml 2s cpatoepser e eR RRI ERR De RR UU R RD E d 56 Bit Twiddling Lco re br RE RRERREREEE E A Re xEE 59 Working Through the Code Cylon Eyes eeeeee cree eee ee 60 Bit TWiddling and Cylon Eyes us ceed ete Deere et emere 61 Bit Shiftiriq eeen cree oer rope Qe HRK EXEC NFORCE 62 Advanced Bit Twiddling Above and Beyond Cylon Eyes 64 Setting Bits WIth OR ceste eh rRR PIS DR tER EDIT OIIER ER 67 Tegaling Bits Witt KOR is coe 225 08s eco teen mete tor meret 69 Clearing a Bit with AND and NOT ee eee eee e eee e ees 70 SHOWINGOMM PEE 71 SUMMON sese sep pe EE vr ve paw Nue Ree SOR n pee ae RUE 75 Ser IO uoces E e VREXERERE E RE A VEE CER ZZ Serial Communication etc ce rk er ogrRRDIE UE SE ERI ERE 77 Implementing Serial Communication on the AVR Loopback Project 81 Setup Configuring the AVR 0 cece cece eee eee tent enee 81 Setup Your Compute ceresc siniwi n emo eee ee 83 Setup USB Serial Adapter cece cece esses 83 Putting It All Together Test Out Your Loopback 86 Troubleshooting Serial Connections 0 cece eee eee ees 87 Configuring USART The Nitty Gritty Details 20 88 AVR Square Wave Organ cece cece cece ence nnn 95 Making Music with Your Micro 0 eee cece eee e eee e ees 96 Make AVR Programming The Or
25. ck up to see the exact string of commands the makefile ran on your behalf and revisit Make and Makefiles on page 19 If you just want to get on with more programming and everything worked we re done here Chapter 2 Programming AVRs Al
26. d something to learn but it was almost never the same thing for everyone In building your microcontroller projects you re going to need to think both like a software type and a hardware type even if only one of these initially comes natu rally to you At times you re going to need to debug code algorithms and at other times you re going to need to figure out exactly what s going on electrically when that button is pushed or that motor is energized This need to put on two different hats sometimes even at the same time characterizes microcontroller and embed ded applications Throughout this book there ll be some concepts that are too obvious to you but which may be entirely perplexing to others l Il be swapping my software type and hardware type hats accordingly In the end you ll become familiar enough with both worlds that you ll be able to navigate the middle ground You ll know you ve reached embedded design nirvana when you begin coding with the hardware Then you ll have become a microcontroller type Manifesto And so we come to my sincerest goalin writing this book instead of simply another blinky LEDs on an Arduino manual to turn you into a true microcontroller type Although the Arduino environment is good for getting people hooked on microcontrollers it s a cheap high Arduino Wiring goes to great lengths to abstract away from the microcontroller s hardware Here want to teach you about the Make AVR Programming
27. d the virtual world Why This Book Are you sending a balloon with a small payload to near space Need a small bit of computing power to read your temperature sensors and accelerometer and log the data to an SD card without using too much power A microcontroller is just what you need Would you like to build your own small robot or a cute interactive toy for your niece There s a microcontroller application there too I m sure that you ve seen a million interesting projects online wondered How d they do that and gotten the answer a microcontroller Without their capable microcontroller brains the homegrown 3D printing scene would be nowhere Microcontrollers are at the center of an emerging culture of people building the previously impossible The goal of this book is to get you building projects with microcontrollers and writing your own firmware or using libraries from other people in C I ve chosen the Atmel AVR series microcontrollers to focus on because they have a fantastic free and open toolchain easily available programming hardware and many of you probably have one or two already on hand in the form of Arduinos A large part of the collaborative hacker community uses these chips so it s as good a starting point as any The ATmega168 chip family that we ll be using is right now the sweet spot in price per functionality but it is not hard to port your code to smaller and cheaper if you want to or move over to other AVR
28. d these files Separating your code into functionally different files is good software design but it means that you need to remember all of the dependencies among the different files in your codebase and type out potentially many filenames each time you compile Keeping track of all of these dependencies manually can quickly become unrea sonable and it was only a few years after C was invented that the make utility was designed to help Instead of compiling your files together manually a file called a makefile contains a bunch of dependency rules and instructions for processing them and then you just run the make command and everything compiles That s the idea anyway So for instance you can explicitly compile all of your source files together like this gcc main c another file c seriallibrary c o main which makes an executable file main from all of the listed c files Or you can write a makefile that maps out these dependencies main main c another file c serialLibrary c and then simply type make main or even simpler make The make program knows that names on the left side of the are targets and on the right their dependen cies If you need to run special commands to make the targets from their depen dencies these commands are listed on the next line indented with a tab Dependencies can in turn have other dependencies and make will keep digging deeper until it can resolve them Things get complicated with
29. e 364 2C Demno LTY o rearua tise n o ur Chae daa eee OUR RR 365 2C Thermometer Detto oes sepe peri be R E RI RE PETS 369 SPI and I2C Datalloguel i cecinit ee beni Mise eerte cies 371 Poititers in EEPROM seieysepde cro pPEPSC UE UR OC IV 375 The UART Serial Menu ier enpe re E RR RO een ak eaves 376 The Logger s Event EOOD ves cox ve EXSE chara PXWESPEEEES 377 Using Flash Program Memory 379 Using Flash Program Memory 0 cceee eect cece tent eneeeee 379 Memory Addresses c ccsosesene e eee ee d dunes Ea het 381 The Address Of Operator amp 0 0 ccc cece ccc eee ence een eneeees 382 usn P MM 385 PojutetsihiBtief es ses ses eg abes erb Ue ERE E 385 Pointers as Arguments to Functions eee 388 SUMMA reie anaa a aO WIRE RR aaa en vad ean 392 Optional Dereferencing Pointers 0 cece eee ences 393 Talking VORMEtCR sic sctereistewereadarsard CROP RR abbey errs a 394 PROGMEM Data Structures and the Header File 395 Sound Playback and Voltage Reading The c File 400 Generating the Audio Data 0 cece eee cence tent ee eens 404 Differential Pulse Code Modulation cseeeee eee es 404 Encoding TWo bit DPCM ceeer te teer OY pU PERUP Dg 405 Encoding DPCM wave2DPCM py 2 0 cee ce cence eee eeee 408 EEPROM sc cttesvseostdsceicecsdesivesevincs 413 Using EEPROM icitciua cd cueieduarhaniriee duensadues Gn
30. e breadboard and labels the signal lines as well If you re ever placing an order with them these little tools are well worth a dollar Alternatively you can take some perfboard and wire up a similar breakout yourself You ll need a bunch of breakaway header pins a bit of wire and some patience Make sure you test and label the outputs when you re done For the long run l d recommend making yourself a programming adapter of some kind The idea is to hardwire up a connector that either plugs into a breadboard or sits on top of the chip that you can use to replace the multiple wires that connect the programmer to the chip Figure 2 9 demonstrates a variety of ways to simplify connections between your AVR and programmer Chapter 2 Programming AVRs 33 Getting Started Blinking LEDs 34 Figure 2 9 Programming adapters for ISP 6 pin headers From the top going clockwise 1 AUSBTiny programmer with the standard 6 pin ISP header 2 Azero insertion force ZIF socket that wired up to connect to the 6 pin ISP header and the ATmegax8 series chips For fun also added a power on LED and an external power connection so that it can work with nonself powered flash programmers You can find ZIF sockets cheap at online auction sites The underlying perfboard came from Radio Shack Next is a deluxe custom board that had made as a precursor to a board I used in teaching an AVR class This one breaks out all the ports into bank
31. e going to need some red wire for 5 V and some black wire for GND If you re using an Arduino as programmer the 5 V and GND connections are nicely labelled on the board Use red and black wires to hook them up to the breadboard s power rails Make AVR Programming Getting Started Blinking LEDs ISP Connectors No RESET PC6 E 1 28 PC5 ADC5 SCL Six Pin Connector RXD PDO 2 27 __ PC4 ADC4 SDA TxD PD1 3 26 __ PC3 ADC3 VCC 2 1 MISO INTO PD2 4 25 _ PC2 ADC2 MOSI 4 3 SCK OC2B INT1 PD3 5 24 __ PC1 ADC1 GND 6 5 RESET TO PDA 6 23 _ Pco ADCO vcc i 7 22 Ml cno Ten Pin Connector GND MENS 21 AREF XTAL1 PB6 9 20 AVCC VCC 2 1 MOSI XTAL2 PB7 10 19 PBS SCK GND 4 3 Unused OCOB T1 PDS _ 11 18 _ PB4 MISO GND 6 5 RESET OCOA AINO PD6 C 12 17 BH PB3 Mos OC2A GND 8 7 SCK AIN1 PD7 C 13 16 PB2 SS OC1B GND 10 SUMISO CLKO PB0 C 14 15 C PB1 OC1A Figure 2 5 AVR ISP programming pins If you re using a programmer that ends in a standard 6 pin or 10 pin two row IDC connector getting the pinout correct can be a little bit tricky For orientation set the connector on the table so that you re looking down into the holes and notice the location of the plastic tab The cable should also have a red stripe on the same side that has the VCC pin which is a very helpful mnemonic Hook up the power pins so that they look like Figure 2 6
32. ers work about the same and the differences there won t amount to much more than a few tweaks to a file that you ll use over and over again Flash programmers after all are just USB devices that send bytes of your code across to the AVR chip On the software side different development packages will have differentlooks and feels butin the end itall comes down to editing code compiling it and then sending it off to the hardware programmer Programming the AVR Hu The words program programmer and programming are overloaded in the microcontroller world We as programmers write programs compile them and then use a flash programmer to program the AVRs which then runs our program Pshwew Let s step through the actual procedure and see what s actually going on 13 Programming the AVR What You Need For this chapter you ll just need the basic kit as de e An LED any color and an appropriately sized scribed in The Basic Kit on page xiv For conve resistor 200 500 ohms nience l ve summarized that here e A source of 5 V DC power if not supplied by e Asolderless breadboard your ISP a 4xAA battery pack is nice anyway e Wire jumpers to plug in to the breadboard e One 100 nF 0 1 uF capacitor to smooth out the AVR s power supply e An ISP programmer e An ATmega168 168A 168P or 168PA Toolchain It s a long and winding road from the code you type into your editor to a chip on your desk that turns
33. et me provide you with a shopping list Order this stuff now so that you can be ready to start programming chips in a few days when the delivery truck shows up The Basic Kit Here is a basic kit of parts that you ll need throughout the rest of your AVR life A lot of this gearis multipurpose and you ll have some of these parts on handif you re playing around with electronics The following is the basic kit that you ll use for programming AVRs throughout the book A solderless breadboard or two or three like the 800 contact type because of the extra working space but a few smaller breadboards can be nice for building subcircuits on You can never have too much workspace Anumber of wire jumpers to plug in to the breadboard really like the prebuilt ones with rubber grips and pins on the end You can often find these sold in combination with breadboards for cheap at online auction websites You should probably have a small resistor assortment on hand You ll need a bunch in the 200 500 ohm range for LEDs a few around 1k ohm and at least five in the 10k ohm range An ISP programmer see Flash Programmers Have Known and Loved on page 28 for recommendations or Arduino see AVR and the Arduino on page 20 An ATmega168 168A 168P or 168PA Make sure you get one in the DIP package if you want to plug it into the breadboard The parts l m using at the moment are called ATMEGA 168A PU where the PU denotes a DIP pa
34. gan Library sss nnne 98 Ln zo dero 99 EXIqGOodIB5 oooc ees E rU Perse er E Re DE 102 KJ ee EE 103 B Digital WPT iis ox ERE AER RRER ERE ARTEENEE 105 Pushbuttons SWitclyes EEIG n rentre Debt Eme ess 105 Configuring Input DDRs PORTs and PINS ssuuseuse 108 Interpreting Button PRESSES ocee esce emere tener meme 109 Changing State case oneccec xe Php Ee P RE EEE Da ERE 112 DEDOUMEING Bcc ce ee x ome setae wey see UA DUC NI o tad seed 113 Debounce Example sessesesesseeeee eee 115 AVEUMUSIC BOX oeste epp ppp sae ae Y ROSEO ES OREL saa Deen 117 The Coden cse terea Exo IE Rx IR E I Buh qu ni Eat qe 117 BOSS BUOM core dre eee eem ete ea e rx To Re ns 119 Desktop side Scripting irn inresa per e Re ere rDRRRI a Y 120 EXteBSIOfl oec uote hero FCRI REDE E E e Ere 124 7 Analog to Digital Conversion l 125 ADC Hardware Overview sssssssesesese nme 126 Light Metet or eeroe er PE PEURURPPIGA RN SERIO PUPPUPEFRXOE 129 TECE M mm 129 Thie Code esser exe xp pL REC Pa por ERE RE deROK ERE GE deg 135 ADC InitialliZatiOFi q cosi ep eer a y qe E e RSS 137 EXEeDSIODS onno ne a E RP ROPA RP CEU Pa DPG S 139 SIGWSCODE cus cure ceci Vere EE REN UA IER 140 The AVR Gode ccc earca e repe a YO PbpeY erre TRY Er Orer YR 141 The Desktop Code cese aciakateaouses Up AE REESE aS 143 Syhierdles eb ueseppievememerarRAERISRS CLP IG ID CADRES 145 AVR Night Light and t
35. had some experience programming an Arduino and you d like to get to know the AVR chip more intimately this book is for you Learn the hardware apply the hardware love the hardware US 44 99 CAN 47 99 ISBN 978 1 4493 5578 4 a 54499 INN n 4 9 78144935578 makezine com Make AVR Programming Elliot Williams MAKERMEDIA SEBASTOPOL CA M Make AVR Programming by Elliot Williams Copyright 2014 Elliot Williams All rights reserved Printed in the United States of America Published by Maker Media Inc 1005 Gravenstein Highway North Sebastopol CA 95472 Maker Media books may be purchased for educational business or sales promotional use Online editions are also available for most titles http Z my safaribooksonline com For more information contact O Reilly Media s corporate institutional sales department 800 998 9938 or corporate oreilly com Editor Patrick Di Justo Indexer Judy McConville Production Editor Kara Ebrahim Cover Designer Shawn Wallace Copyeditor Kim Cofer Interior Designer Monica Kamsvaag Proofreader Amanda Kersey Illustrator Rebecca Demarest February 2014 First Edition Revision History for the First Edition 2014 01 24 First release 2014 02 14 Second release See http oreilly com catalog errata csp isbn 9781449355784 for release details The Make logo and Maker Media logo are registered trademarks of Maker Media Inc
36. he Arduino s pin names Digital 13 and so on Figure 2 2 which is similar to the sweet ASCII art in arduino 1 0 4 hardware arduino variants standard pins arduino h should help Chapter 2 Programming AVRs 21 AVR and the Arduino 22 RESET PCe DO PDO D1 PD1 D2 PD2 D3 PD3 D4 PD4 PC5 A5 PC4 A4 PC3 A3 PC2 A2 PC1 A1 PCO A0 o AON Oo OC A OUO N FR PB7 10 PB5 D13 SCk PWM D5 PD5 11 PB4 D12 MISO PWM D6 PD6 12 PB3 D11 PWM MOSI D7 PD7 13 PB2 D10 PWM PB1 D9 PWM Figure 2 2 AVR pinout and Arduino labels So if you re working along with code from this book and you need an LED con nected to pin PBO for instance you ll want to hook up the same LED to your Ardu ino s Digital 8 pin And see how the Arduino doesn t use pins PB6 and PB7 Finally the Arduino bootloader needs to use the watchdog timer which is a timer that effectively reboots your AVR chip automatically if your code gets hung up and doesn t check in every once in a while We won t even use the watchdog timer in this book but if you need to make a very robust design it s a nice trick to have up your sleeve But don t let these gripes overshadow the main point an Arduino can also be turned into a fine C language AVR programming platform And besides if you ve got one sitting on your desk you might as well use it Make AVR Programming AVR and the A
37. he Multiplexer sseeeeeeeeese 145 MultiplexiTig oss cxeer exe E YXUUbUEE A E X PUER EE TER 145 Settings MUXBIES esee esee tne ieia D T names 146 The Circuit esni dini ns e ora eren orea Se ebbrg 148 Bie o EM 148 SUMMA E ere bte mekiteb bt amexicex NNI eX dede 150 Part ll Intermediate AVR 8 Hardware Interrupts 153 External Interrupts 101 Real time Button Pressing Examples 155 External Interrupt 0 Example cece cece cece eee eene 156 Pin Change Interrupt Example 0 cee ee eee eee eeees 161 Capacitive SeblSOr cendres seas dab sie pU eT eMe P RR ds 164 The Sensor esci rper bes Etpe sone es Exe neon Ene dide 165 Table of Contents 8 10 11 12 Tie Code iso a ree Ee ep E REP pe edu 168 Global Volatile Variables celle 170 Debugging the Circuit n eses ence ter teneee tene eves 173 Introduction to the Timer Counter Hardware 175 Timer Counters Why and How 0e cee ee eee cee cet eet eee 175 Test Your Reaction IME cadens cued cau Ot Ote nece Deren 178 Using Timer 0 for a Better 8 Bit Organ ce cee eee eee eee 182 AMRI Ossau onga ken serena ppP e Or VU RE PP UP dO PS 186 The CCUG iiss veer can ce did RRG RR ORTA RYAWGG dg Ga v Ye Xa 188 CPU Speed zi eire cor edu e rua a Ox RR NR OR PRAES 189 AM Radio The Code icc ositase ae zercrrte ud e vinosa 190 SUMMANY uunc ito treo br m br tr RB Us CUR E a 196 Pulse Wid
38. ill enable you to compile and flash valid C code with minimal changes to your old workflow Follow these steps whether you re pro gramming for the Arduino s onboard AVR chip or for an external AVR target on a breadboard anytime you want to write straight AVR C code within the Arduino environment To get running in C with the Arduino IDE there are two things that you ll have to do only once before you even start the IDE Copy over whatever libraries you need to go with your code In writing the code for this book ended up using a few bits of common code in almost every project It makes more sense to put all of these common files in one place To use this library of common code create a directory in your libraries folder sketchbook libraries on Linux and Documents Arduino libraries on Win dows and copy your common code here Now you ll be able to use it within any other program by simply by importing the library So copy the AVR Programming Library folder out of the code directory and into your sketches library right now If you re going to be coding for an ATmega 328P either in an Arduino the Uno for instance or as a standalone chip fix up your portpins h file See portpins h and the Arduino IDE on page 25 If you re going to use an ATmega168 or other chips you don t have to follow this step but it won t hurt Now that your Arduino IDE is set up it s time to get coding In this example l Il assume that you d like to cop
39. illiamps Flashing AVR chips using the Arduino as a programmer Now that the hardware is wired up let s use it to program the AVR chip Following these instruction will turn your Arduino into a flash programmer When you want your Arduino back as an Arduino you can just reprogram it as usual 1 Verify that your Arduino board type is set up correctly Tools gt Board Uno in my case 2 Flash the example code ArduinolSP into the Arduino hardware the usual Ar duino way Make AVR Programming AVR and the Arduino 3 If you don t have a sketch ready to upload yet go back to Writing C in the Arduino IDE on page 24 and set up blinkLED c 4 Select Tools Programmer gt Arduino as ISP to program through the Arduino hardware instead of programming the Arduino itself 5 Select Tools gt Board gt Arduino Pro Mini 8 MHz w ATmega168 because we re targeting an ATmega168 running at 8 MHz Nobody will know it s not inside an Arduino Pro 6 Shift click on the Upload button Shift Ctrl U to flash your code into the AVR target If you re too accustomed to just clicking the Upload button and forget to press Shift here you ll get an error like avrdude stk500 disable pro tocol error expect 0x14 resp 0x10 7 If you want to see what s going on in the background click File Preferences gt Show verbose output 8 Otherwise sit back and watch your AVR target get programmed Does it blink Sweet Using Ardu
40. ino as hardware programmer without the Arduino IDE Because it s possible to use your Arduino as a flash programmer from within the Arduino IDE you re probably wondering if it s possible to flash arbitrary AVR chips without using the Arduino IDE as well Of course it is First make sure that your Arduino is wired up as in Figure 2 3 and that you ve uploaded the ArduinolSP sketch to the Arduino Once you ve done that you won t need to touch the Arduino IDE again if you don t want to Open up the blinkLED directory from the software that accompanies this book Because you re using makefiles to configure and compile your code you re going to need to edit Makefile by hand so that it knows how to use the Arduino pro grammer In short you want to use programmer type avrisp at 19 200 baud on the correct serial port For Linux try PROGRAMMER TYPE avrisp PROGRAMMER ARGS b 19200 P dev ttyACMO For Windows try PROGRAMMER TYPE avrisp PROGRAMMER ARGS b 19200 P com5 For Macintosh using the Uno or Mega 2560 try PROGRAMMER TYPE avrisp PROGRAMMER ARGS b 19200 P dev tty usbmodemXXXXXXX For Macintosh using any other Arduino try Chapter 2 Programming AVRs 27 Other Hardware Programmers PROGRAMMER TYPE PROGRAMMER ARGS avrisp b 19200 P dev tty usbserialXXXXXXX You can figure out which port name the Arduino connects to from within the Ar duino environment under Tools gt Serial Port On Windows syste
41. iny or USBasp you won t have to enter anything here just leave the line blank If you are using a serial based programmer you ll need to specify the serial port and baud rate using the P and b options respectively Chapter 2 Programming AVRs 39 Getting Started Blinking LEDs 40 See Common AVRDUDE Configurations on page 38 for hints or scroll down to the very bottom of the makefile to see some examples for common pro grammersand configurations And remember this is just passing these options onto AVRDUDE so whatever ittookto get AVRDUDE working on the command line except for processor and programmer type you ll need to add in here Flash OK by now you re dying to see some blinking lights can t blame you If you ve already got a command line window open change directory to the blinkLED project and type make flash If all of the preparations up to now went well con gratulations Your sweet reward is a slowly blinking LED on the breadboard You want more Open up the blinkLED c file in your editor and read through Try changing the delay times to change the blink rate of the LED for instance make it blink on for just a very short time between long periods of being off Each time you edit the code save it and then type make flash again Or if you re using an editor that lets you compile and flash from within it it s even simpler Take the time now to get used to the edit compile flash cycle while the toolchai
42. makefiles when you add in variables and wildcards that match any filenames You can start to write generic rules that compile any cfiles together for example and then you only have to change the variable definitions when you move a makefile from project to project I m including a preconfigured makefile for each project in this book s code repos itory You may be able to use them as is but we also might have different AVR programmers and different serial ports so you ll eventually want to at least modify some of the definitions We ll step through configuring the makefile to fit your setup in Configuring Your Makefile on page 38 Chapter 2 Programming AVRs 19 AVR and the Arduino 20 Now that you ve got the software set up all you need is to connect up a flash programmer to the chip and test it out Here you ll have two choices If you don t have a dedicated AVRflash programmer yet but you have an Arduino lying around the next chapter is for you If you d like to buy a dedicated AVR flash programmer have some advice in Other Hardware Programmers on page 28 Otherwise if you ve already got a flash programmer you may proceed straight to Getting Start ed Blinking LEDs on page 29 and get started AVR and the Arduino A bunch of you are going to be used to the Arduino programming environment That s great In this book l Il be teaching you all of the powerful nitty gritty that Arduino hides from you in the name of easy
43. ming in standard C us ing makefiles and all that you ll be learning some transferrable skills that will work on other hardware platforms and microprocessor architectures And then if you eventually swap out the Arduino as programmer for dedicated hardware you won t even notice AVR on a breadboard than using the Arduino hardware However using the Arduino as a hardware program mer is tremendously comfortable even if you re used to more advanced tools With just six wires between the Arduino and your breadboard you ve got a The Arduino Is an AVR If you re shy about leaving the comfortable Arduino IDE you don t have to With a few tweaks the Arduino compiler can be fooled into compiling standard C code which you can then flash directly to the AVR that lives inside the Arduino hardware So if you re coming from the Arduino world and you d like to get started with this book right away you can The reason that this all works is that the Arduino environment is really just a thin GUI layer that ties together the standard AVR toolchain GCC as a compiler and AVRDUDE to talk to the flash programmer In short you can start off with the full Arduino IDE and slowly migrate over to doing everything manually or vice versa Chapter 2 Programming AVRs 23 AVR and the Arduino 24 Writing C in the Arduino IDE If you re used to the Arduino IDE and don t want to try out another code editor for instance the following steps w
44. ms it will be a COM port and on Linux or OSX systems it will be dev tty something Once your makefile is configured for the Arduino as programmer you re all set to flash the code over to your chip If you ve got a terminal window open and you re in the blinkLED directory typing make flash should do it Other Hardware Programmers If you don t have an Arduino handy or if you d like the convenience of a dedicated hardware flash programmer you ve got a lot of good choices If you ve got the software already set up a flash programmer is your missing link If you already got your firmware flashed by following the previous Arduino instructions you can skip this section or read on for curiosity s sake Flash Programmers Have Known and Loved You have a large number of choices for hardware flash programmers A program mer can be as simple as a couple of wires but most of them actually use an AVR or other microcontroller to interface between your computer and the AVR that you d like to program Here is a shortened list of some of the good choices you have available Parallel port The first programmer ever used was not really any programmer at all but instead just a cable with five wires soldered to a parallel port D sub connector This works because AVRDUDE knows how to toggle the lines of a parallel port to program your AVR chips directly Unfortunately this programming method requires a parallel port on your computer which is a
45. n is unfamiliar but the code is simple Once the code and or the circuits start to get complicated you ll be glad to have faith in the toolchain Troubleshooting We did most of the troubleshooting for this project as we went along Is the power working It should be as long as the power LED is lit Does the AVR receive this power A quick way to double check is to put an LED across the AVR power pins where you ve got a capacitor The next things to check are the connections because it s easy to get these wrong But because we tested them using AVRDUDE we know that the programmer is able to communicate with the AVR chip so all should be well So with the hardware all debugged that only leaves the software and in this case it s about as simple as can be What s more I ve double checked it about a billion times so it should compile just fine Barring the pindefs h problem if you re using an Arduino IDE for compiling in which case see portpins h and the Arduino IDE on page 25 Because everything s working just fine a good exercise at this point is to break the code and see what happens C compilers are great when it comes to complaining that something s wrong but not as helpful as you d like when it comes to pin pointing the cause of the error For instance pick a line of code that ends with a and delete the semicolon Save the bad code and type make to see what happens All sorts of errors no But none of them tell you
46. nced AVR Topics 13 14 15 18 Advanced PWM Tricks eeeees 269 Direct Digital Synthesis eeces cepere erem hee 270 Making a Sine Wave axe nsexvai EX PPOPERECC ERU OREREPC E RR UR 274 Next Steps Mixing and Volume 0 cece sence cent enters 277 MIXING essasi esee ht exe p aed esaev a a cedaede at 277 Dynamic Volume Control csc exter rr eher sage 280 Polling USART vaiccsiiis the EXT ER EDEN ERO ER TERIS 283 ADSREnVelopB avec c2ce tae a nd Pone COUTE RA 283 Auxiliary PIles s oexiasdevippecckrie p e prO ERE RE RUTEERNES 284 SWITCHES ieo esee cesse we ons esesesessev 287 Controlling Big Loads Switches vrisees eid erben ed eee 288 Bipolar Juniction Transistofs elec rive eO Rees 290 MOSEETS aaj dunce epospirsp bn pda e eb p bb eda ER n 291 Power MOSFET avere eoram prier iano E EAEE oe 293 Relays ccpe E A ed RpUF UC E FUE VERE EA pea E NTIDUE ER Ed ER 294 lacs alid a crccseusersdadeseesossdamers caeesdawexeasen 5 295 Switches SUMMALY oiscadtecae edru i nEn ETEN EEEE PEREN PUE 296 eor TET 297 Advanced Motors cccccccccesccccess 305 Going in Reverse H Bridges cece cece eee ee eee e eee e ees 306 Code Taking Your H Bridge Out for aSpin 0 eee eee eee 309 Experts Only H Bridge err rere vrbe rer phe ben mer pne 312 PWM and the H Bridge sss 313 Drive Modes Sign Magnitude cece cece eee e eee ees 314 Drive Modes L
47. nd options will work Configuring Your Makefile Playing around with AVRDUDE by itself is good for debugging and making sure everything works but you d hate to have to remember all this much less type this all out every time And that s where the makefile comes in As mentioned in Make and Makefiles on page 19 most of the makefile is generic info for the compiler about how to compile and link program files for the AVR and you ll never need to modify these generic bits On the other hand the top few lines include some definitions that are specific to the project at hand and to your com pilation and flash programming setup We re going to need to edit some of these by hand Copy the blinkLED folder from the book s source code library and open up Makefile with your programming editor Let s step through the bits you ll need to change 38 Make AVR Programming Getting Started Blinking LEDs MCU This is the type of AVR chip you re using In our case we re using an ATmega168 so it reads atmega168 For a complete list of supported chips type avr gcc target help and about halfway down you ll find a list of Known MCU names F CPU This definition tells the compiler what clock speed your chip is running at If you don t have an external clock source like a crystal this is either 1 000 000 or 8 000 000 for the ATmega chips one megahertz or eight megahertz Get ting this right will matter for the timing of serial communic
48. ns on three different operating systems so the number of possible configurations is ridiculous Here are some examples of the types of configurations that you ll encounter to get you started Windows Linux or Mac OS with USBTiny ATmega168P avrdude p m168p c usbtiny Because USBTiny and USBasp programmers don t need any additional options the command is the same across all three operating systems For the following you need to type the commands all on one line Windows with ArduinolSP ATmega168p avrdude p m168p c avrisp P com5 b 19200 Linux with ArduinolSP ATmega168p avrdude p m168p c avrisp P dev ttyACMO b 19200 Mac OS with ArduinolSP ATmega168p avrdude p m168p c avrisp P dev tty usbserial A5307bQF b 19200 ArduinolSP needs the P flag for the serial port To find out which serial port you need open up the Ar duino IDE and look under Tools gt Serial Ports with the Arduino plugged in The Arduino plugs into USB but it s got an onboard serial emulator that makes it show up as a serial port device Windows with parallel port programming ca ble ATmega88 avrdude p m88 c dapa P lpti Linux with parallel port programming cable ATmega168p avrdude p m88 c dapa P dev parportO hope these examples get you squared away or at least put you on the right path If not an Internet search will probably yield results In most all situa tions just a couple of tweaks to the same basic com ma
49. nt to replace the portpins h file with a more recent ver sion On my system found the file in arduino 1 0 4 hardware tools avr lib avr include avr portpins h Replace this file with the version that I ve included with the book s code library and you should be able to just write C For whatever reason the portpins h include file that comes with Arduino 1 0 4 and previous is old 2006 and doesn t conform to modern usage The end result is that standard pin name macros like PB1 don t end up getting defined for the mega328 chip while the old style PORTB1 macros are If you see errors like PB1 undeclared first use in this function that s the portpins h bug Flashing the Arduino as target This is super simple from within the Arduino IDE because programming the Ar duino is what it s meant to do The only difference here is that you re writing your code in real portable C rather than Arduinoese 1 Verify that your board type is selected in Tools gt Board 2 Make sure you ve included your library using Sketch gt Import Libraries and that the tinclude lines appear in the first sketch tab 3 Click Upload or type Ctrl U to flash your code into the AVR inside the Arduino hardware Easy The Arduino Is an AVR Programmer Or at least it can be In this section you re not going to be writing your code into the Arduino as a target but rather using it as the middleman You ve got an AVR chip that you ve stuck into a
50. ocked Anti phase cceccceeeeeeeees 314 Drive Modes ComparisOn esses 315 Stepper MOLOIS nineio a o Rm UR Rr RR UR ee D C 318 Kinds of Stepper Motors 0 cece cece meme 319 Full Stepping and Half Stepping cece cece eee e ee eeee 320 Identification of Stepper Motor Wires cece cece eee e ees 323 Too Many WIES sce circo nta eo ne dia iR Seen pei qe 323 Dual H Bridge Chips The SN754410 eee eee eee eee eee e ees 325 The Code i si sore deel nets SIR e Ente ime iint nee RENS 327 Acceleration Control ces cee cete teet mee mee eene en 331 i Te EOSTS PUIG RETE 334 Haw SPI WORKS steel er Seated PERDE oT ex vios ees 338 Table of Contents vii 17 18 19 Bit Trading Example oce nenne 340 SMi REJSTES esto Hebraeo ne Rep ep epe e Keds 340 EEPROM External Memory cece cece cece ence ee enenenes 343 External Memory exiit ead e ber eae dine RU PER Re 344 SPI Demo HOOKUPS ovr ocx REOR EP EUR UE EDU EX TEE ERE 347 SPI Demo COGS o bcr exerc teur px ec HERR e RE Rd 348 SPI EEPROM Library Header cere eem 350 SPI EEPROM Library C Code ce cece cece cece cee eneeeenees 352 iuc TT 354 SPl tradeByte eer i senn pe e EAEE AAEREN AARETE 355 Convenience Functions ssssesssssssssreesesorrsesssess 356 SUMMA iinan aa EAE ERA EE LL DLL 357 How I2G WOS ereinen iiaa roter Ca poe tee Gre trece EE 360 2C Delo HOOKUP ninina aei en EX OU DURO EEEE e
51. ook visit https github com hexagon5un AVR Programming and click the Download ZIP button The blinking LED example is in this chapter s folder Please double check that you ve installed an appropriate software toolchain for your OS or modified the Arduino environment to work with C language code If Chapter 2 Programming AVRs 29 Getting Started Blinking LEDs 30 you re using an Arduino as a hardware programmer make sure that you ve flashed ArduinoISP Fasten your seatbelts here we go Figure 2 4 Some programmer options Hookup The overview of wiring for this chapter is that we re going to be hooking up the programmer including its power supply pins to the AVR chip Each of these pins has a specific function and they re labelled in Figure 2 5 The whole point is to make sure that the programmer s MOSI pin is connected to the AVR s MOSI pin PB3 and so on We ll also wire up an LED for display purposes and optionally wire up another as a power on indicator If you re using an Arduino as your programmer your wiring will end up looking like Figure 2 3 but you can also assemble the circuit piecewise as we re doing here First hook up the power and verify that it s working and then move on to the MOST MISO SCK and RESET wires The principle is exactly the same For the first step let s set up the power rails of your breadboard to double check that we ve got the pinout from the programmer s connector right You r
52. ows or Linux and you can be sure that you ll always know what you re doing wherever you go After all the target of all our work here is a little 8 bit microcontroller that doesn t know anything about what operating system you use Make AVR Programming Programming the AVR To Recap Plan This stage just requires your brain some paper and a pencil and maybe the AVR data sheet so you can figure out which parts the onboard hardware can help you with Think through what you need the chip to do and breakit up into functions for each logical step Code Write your program using whatever text code editor makes you happy Here you re just translating the ideas behind the functions into valid C code Compile Turn your C code into AVR machine code with avr gcc and its associated tools mostlikely run from a makefile Type make and read through the compiler errors then go back and fix them Flash Hook up a flash programmer to your target AVRandthen run AVRDUDE to send the machine code through the programmer to the AVR chip which saves it in flash memory Or just type make flash and watch it go Did flashing work Test Once you ve uploaded your code to the AVR does it do what you want it to Test it under many differing conditions before you re sure You ll find all sorts of interesting real world situations where your sensors aren t reporting data as you thought they would Now s a good time to find that out
53. piler avr gcc Ta ei Avrdude amp Flash Programmer Figure 2 1 AVR programming toolchain Aside on Windows Editors Both Programmer s Notepad and Notepad let you compile and flash code directly from the editor with a single button push which is handy because the Windows command line isn t very familiar to most folks In Programmer s Notepad there are options for calling make flash to open up a command window in the current directory compile your code and flash it to the AVR The K leaves the window open after it s done so you can read any errors in compiling or up loading that may have occurred You can also run it with C if you don t want to see the output your makefile in the Tools pull down menu and you ll see the results of your compilation and uploading in the Output panel at the bottom of the screen With both of these editors you can also bind these actions to a key combination so that compiling and uploading your code is as easy as it would be in an In Notepad usetheRun pull down menu andtype DE Pretty slick in cmd K cd d S CURRENT DIRECTORY amp amp Of course if you want to geta whole IDE won tstop you but it s not at all necessary For Windows Atmel Studio is comprehensive and centered on the task at hand If you use Eclipse there are AVR plug ins as well If you don t know what any of this means skip this paragraph learning a new IDE is itself a day s work and too much detail
54. r a few years They come in kits don t cost too much money and have very good build instructions and support Like the USBTiny project that it s based on LadyAda s programmer can power your project off the USB bus If you d like an easy kit to solder together that builds a useful tool this is a good way to go A family portrait of some of my programmers can be found in Figure 2 4 from center top and going clockwise 1 An Arduino and six wires makes a totally workable flash programmer USBTinyISP USBasp from BaiTe in China USBTiny tiny version from ehajo de Uu A wW N A homemade programming spider which plugs into a breadboard around the AVR chip and connects up the programming power and reset pins the right way every time If you re at all handy with a soldering iron and perfboard you should make one of these Getting Started Blinking LEDs OK let s get down to business and compile flash and test our first AVR microcon troller project This is not the coolest most interesting project in this book The point is to verify that all parts of the programming toolchain are working for you before we start to get a little fancy In order to minimize the possible ways to mess up we ll build up the simplest possible project that puts the software toolchain together with the flash programmer an AVR chip and the most minimal possbile feedback a single LED To download the code for this project and for the rest of the b
55. r power adapter or remember to bring batteries along with you all you need for flashing com munications and power is a USB cable Arduino Cons As good as the Arduino hardware is as a generic AVR development platform it s not perfect For use with this book and our examples there are a number of dis advantages to using an Arduino instead of just plugging an AVR chip into a breadboard Make AVR Programming AVR and the Arduino Probably the first among these disadvantages is the lack of the breadboard itself Shields are great for finished products but when l m building up a hardware section for the first time it s nice to test it out on something more flexible like a breadboard find that the more complicated my external circuitry gets the less suitable work ing on the Arduino becomes The Arduino is great for plugging a few LEDs or a couple of sensors into But when things get interesting end up having to jumper the Arduino into the breadboard with 10 or more wires like some demented spider and then my dog knocks something loose and it takes a long while to debug the problem and that s when wish I d just stuck a chip into the breadboard in the first place True story Another downside to using an Arduino as an AVR development platform is that a few ports and pins are already irreversibly wired up and unavailable for use For instance when we make an eight LED POV toy in Chapter 3 you ll discover that two of the pin
56. rduino The Arduino Hardware or Software Both In the next two sections l Il show you how to use the Arduino both the software IDE and the physical hardware as an AVR learning platform The first section cov ers programming the AVR chip that s inside the Arduino as you normally would but using standard C instead of the strange Arduino dialect This way if you ve already got an Arduino in hand but AVR chips and a breadboard in the mail you can get started working through this book by programming the Arduino board directly The second section treats the case where you ve already got your AVR chip on a breadboard and you want to use your Arduino as a hardware flash programmer to transfer the code to the target AVR Following some simple steps you can tem porarily and reversibly use the Arduino as a hardware programmer to flash your code into the bare AVR And then you can decide to continue using the Arduino IDE to compile and send your code or you can use any other code editor and the standard AVR development toolchain The choice is yours Choices Choices From my perspective as an experienced coder and microcontroller user like to use my own favorite de velopment tools rather than the Arduino IDE It s also alot easier and faster to prototype circuits with a bare source of power and a flash programmer that s just as good as any other If you re willing to learn a bit more about the non Arduino toolchain program
57. rrors n Write nothing mode This one lets you test out commands without worrying that you ll acci dently mess up the chip zt Terminal mode This mode lets you talk to the AVR chip directly After the programmer has connected type sig to read the AVR s device signature which makes a quick test of basic communication between the programmer and chip Type help to see all the options C lt config file gt This lets you use a nonstandard configuration file If the version of AVRDUDE that you ve got doesn t support a particular chip or program mer you can often fixit by getting a more recent configuration file l ve included mine in the book s software bundle sU This the command that reads or writes to mem ory You ll almost always be calling this from a makefile but if you d like to dump the memory of an AVR chip to a file or flash in a hex file that someone has already compiled for you this is how you d do it On the other hand you might get an error There are basically four possible errors you ll get depending on whether you ve messed up the wiring specified the wrong chip or programmer type or don t have adequate permissions to use the interface Let s break them down into cases You get an an error that reads avrdude initialization failed rc 1 Double check connections and try again or use F to override this check The dreaded rc 1 error message means that your wiring is messed up Despite what it s
58. rt See The AVR Family of Microcontrollers on page 11 for more on chip selection A USB to serial adapter l m a big fan of the FTDI USB Serial cable Get the 3 3 V compatible one for maximum flexibility It works painlessly with all operating systems and at all speeds A variety of online geekery stores have slightly cheaper options as well Atleast 10 LEDs any color and 10 appropriately sized resistors 200 500 ohms You can never have enough LEDs A source of 5 V DC power optional Many of the ISP programmers provide power to the breadboard If yours doesn t cutting up a 5 V wall wart power supply or using a 4xAA battery pack will work Rechargeable batteries are even better Make AVR Programming For the Basic Projects A small 8 ohm normal speaker and roughly 10 100 uF capacitor got my speaker from an old keyboard toy Two or more pushbuttons Normally open Cheap tactile switches are great e At least 5x 2N7000 MOSFETs e Two light dependent resistors LDRs but you might as well buy an assorted pack e Two potentiometers 10k ohms is ideal Anything above 1k ohms will work For the Intermediate Projects e A piezo disk preferably with wires attached Aservo Any old hobby servo will do get my cheap ones from Tower Hobbies A laser pointer that you re willing to take apart An I2C device to talk to my example uses the very common LM75 tempera ture sensor An SPI device to talk
59. s has a 6 pin SPI header an external power connector on board capacitors and power lights and a 6 pin inline header that s compatible with the FTDI USB Serial cable pinouts Onthe bottom is an experimental 6 pin ISP adaptor that just barely squeezes on top of an AVR chip holding itself in place by bending the pins a little bit got the idea from http elm chan org works avrx report_e html but added on a serial interface as well It s hard to maintain contact with all the pins at once and only use this connector in emergencies Last on the far left is the homemade programming spider that use almost all the time It plugs into a breadboard just around the AVR and connects up everything you need to flash the chip It s the bee s knees and if you re handy Make AVR Programming Getting Started Blinking LEDs with a soldering iron or looking for an excuse to learn making a connector like this is well worth your time AVRDUDE After you ve gotten the circuit breadboarded and the AVR connected up to the programmer you re ready to start talking to the AVR to test the connection And believe it or not the easiest way to do this is to type a little bit Open up a command line window If you re in Linux or Mac OS open up Terminal For Windows open up a Run dialog from the Start menu type in cmd and hit Enter You can then type avrdude to double check your installation You should see a helpful listing of all the
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61. s that l d like to use for LEDs are already hard wired up to the crystal oscillator It s a design trade off because it s clocked with a 16 MHz crystal oscil lator the Arduino is able to run twice as fast as an AVR using only its internal timebase But because the Arduino ties up two of the pins in PORTB you ll only be able to make a six LED cylon without having to do some elaborate coding as a workaround If you want to display a byte s worth of data on PORTB you ll be missing the most significant two bits Arduino boards aren t cheap either just compare an Arduino Uno with the AVR ATmega328p chip that powers it You can buy 8 or 10 AVRs or 20 ATtiny 45s for the price of one Arduino This is because the Arduino has extra hardware power regulation USB to serial and other circuitry onboard which makes them over qualified for many trivial applications This also makes an Arduino too expensive to commit to a one off quickie project and that s a real shame because nothing in the world is better than giving your young niece a goofy microcontroller based toy that you made for around 5 in parts That said if you can prototype the toy faster because everything s wired up for you on the Arduino go for it A goal of this book is that you ll be able to move fluently between the Real AVR world and Arduino More trivially it s a minor pain to be always going back and forth between the pin names in the datasheet PB5 and similar and t
62. s that s blocking the communications or you ve got a loose wire Fix these problems and try again You get an an error that reads avrdude stk500 recv programmer is not responding avrdude done Thank you or avrdude error could not find USB device with vid 0x16c0 pid 0x5dc vendor www fischl de product USBasp or avrdude Error Could not find USBtiny device 0x1781 0xc9f This means AVRDUDE is having trouble finding your programmer In the case of a serial programmer like when you re using the Arduino double checkthe serial port and baud rate flags that you re passing to AVRDUDE If you re using a USB pro grammer make sure that it s recognized by the system On Linux you can type lsusbandlookforthe programmerinthelist On Windows checkforit in the Device Manager Finally if you re on Linux and you receive a permissions error you can fix it by typing sudo avrdude instead of avrdude When you get tired of the extra typing you can give yourself permission to write to USB serial ports In Ubuntu like distributions this means adding yourself to the dialout group For all flavors of Linux you could Chapter 2 Programming AVRs 37 Getting Started Blinking LEDs alternatively write a udev script for the specific programmer You ll find specific directions online if you search avrdude udev and your programmer type Common AVRDUDE Configurations AVRDUDE supports more than 70 programmers and 100 chip types and ru
63. th Modulation 199 Bright and Dim LEDS PWM ic user exer prre RU RR ERR Uer 200 Brute Force PWM Demo icsiecepcedes esepte desk errare 202 Times PWM DEMO eee tnmen cer xem ner eene mm nemen 204 Initializing Timers for PWM Mode eeseeseese 206 PWNVODVARY PII i i rhet ert rm beretr rer R ER I RE hyeme 208 PWM on Any PIN Demo 4 eerte e rr ber Re ER hn 209 Closing Alternatives to PWM and a Timer Checklist 211 Driving Servo Motors 215 co mE 216 The Secret Life of Servos 0 cece cece cece cee ee enne 217 The CIRCE seine eere rte deor wee eene dir ee 218 Te Code TEETH 219 Servo Sundiall c overated er ee er ene Coben es 223 The Bulls EP 224 Ready the Lasetsl ces eceeee e cae eeee rem eren ones 227 lien EET 229 Servo Sundial Calibration v1 04 5 2 errr re eem eem 236 Analog to Digital Conversion ll 243 Voltage MEIER iieicen sex saninin eer eO HOC P UD ERE RUUR 244 Wie CUI oi eene stet OE a A en ne MENTOR es 245 The Code conet era T e TIDCRRAT NITE DEA ERE TA 248 The Footstep Detector ico cue eE ER Ox ER I DOR X PA PERRA 252 MNO GIU osse stew actioned exer OE DRE US E DET ERUNT 253 Dij Enr o E deat ree ieea gar E meee ea 258 Exponentially Weighted Moving Averages ssuse 259 MECHA E HUE 262 vi Make AVR Programming SUMMA o erien p y e pr ceded perpe Cideaaded gad RP Sed 266 Part Ill Adva
64. that l ve ever come across is programmable in C Almost all of what you learn working through this book is transferrable to other chips and other architectures because what you re learning here is the way things work rather than an abstraction wrap ped around the way things work designed to protect you from the way things work Some of what you learn for instance bitwise binary manipulations in Chap ter 4 might seem boring but in the end it will give you simple and direct access to the common hardware bits that are put there to help you and the techniques will work with any brand of microcontroller that you choose to use In short almost none ofthe time you spend learning about how to create projects on the AVR in C will be wasted Yeah it s a bit harder than just reusing someone s shields and code Yeah you might need to stop sometimes and leaf through a C programming book or an electronics text or just look it up on the Net But when youfind outthat you need more processing power or a different set of peripherals you can just buy yourself a 8 chip in place of the 4 one you were using and bring most of your code and more importantly your knowledge along with you This book is meant to be the red pill and sincerely hope that you find it worth your time once you ve seen how deep the rabbit hole goes Preface xiii xiv You Will Need Before we get too much into detail about the AVR chips and what they can do for you l
65. titiiiiimit Made with Fritzing org Figure 2 6 AVR programmer layout no chip yet Now plug the AVR somewhere in the middle of the board Locate pins 7 and 8 which are power and ground for the chip and plug a 100 nF 0 1 uF capacitor across the two power pins Using a red wire connect pin 7 to the VCC rail Wire up pin 8 with a black wire to the GND rail Now you ve completed the setup in Figure 2 7 o9 o9 9 o9 9 9 9 9o 9 9 9 9 9 9 9 9 9 9 9 9 9 EEE EEE 9 9 9 9 9 999999999 o9 o9 9 9 9 9 9 9 9 9 9 5 9 9 9 9 9 99999 999999999999 HEEE Made with 9 Fritzing org Figure 2 7 AVR programmer layout power Now hook up the rest of the programmer s pins Look carefully at Figure 2 5 if it s not clear which pins are which Double check that MOSI on the connector is wired to MOSI on the AVR etc Finally connect up the demo output LED and its resistor as shown in Figure 2 8 When you re done with this we re ready to test it out Make AVR Programming Getting Started Blinking LEDs Made with J Fritzing org Figure 2 8 BlinkLED full setup ISP Headers The Atmel standard 6 pin and 10 pin headers are nice for manufactured boards because they re compact but they re not at all breadboard friendly and that s why we end up with all these wires all over Sparkfun and probably others sell adapters that convert the 5 x 2 and 3 x 2 layouts into a 6 x 1 inline layout that plugs nicely into th
66. u re done working through this book see Atmel s Application Note AVR910 Chapter 2 Programming AVRs 17 The Software Toolchain 18 Linux Setup Setting up the toolchain for programming AVRs on Linux is tremendously simple If you re using a Debian based distribution like Ubuntu or Mint or heck Debian you can simply type all on one line sudo aptitude install avrdude avrdude doc binutils avr avr libc gcc avr gdb avr Red Hat and Fedora users type sudo yum install avrdude avr gcc avr binutils avr libc avr gdb All other Linux users will find that it s easy enough to find source packages for all of the above See http www nongnu org avr libc user manual install_tools html or http avr eclipse sourceforge net wiki index php The AVR GCC Toolchain for details Windows Setup Windows users have two options for the software toolchain one based on the huge Atmel Studio and one based on WinAVR Weighing in at 1 20 the file size and 9 10 ofthe functionality l d choose WinAVR The current download link is from SourceForge andis a little bit old though I ve had no troubles with it It s very well tested and fully debugged A hackerspace in Australia has taken up the task of making a more recent WinAVR clone and you can try your luck with http www makehackvoid com project mhvavrtools if something in WinAVR doesn t work for you That said I ve never had any problems with WinAVR During the installation WinAVR will
67. uggests using F won t help you 99 996 of the time when you see this 36 Make AVR Programming Getting Started Blinking LEDs error your problem is that the six wires connecting your programmer to the AVR chip aren t hooked up right This error can occur when you don t have power to the chip when any of the RESET MISO MOST or SCK lines aren t connected properly or even if you ve got something else plugged into any of these pins that s inter fering with your setup Double check everything until the problem is fixed maybe even unplug and replug your USB programmer You get an an error that reads avrdude Device signature 0x1e9406 avrdude Expected signature for ATmega168P is 1E 94 OB Double check chip or use F to override this check This probably means that you ve got the AVR chip type wrong In the previous example used a mega168 but told it had a mega168P In this case you just need to change the chip type that you re passing as an argument to AVRDUDE If AVR DUDE doesn t have a configuration for the chip you re using you should try using a newer or custom configuration file with the C flag see AVRDUDE Options on page 35 The other source of the Expected signature error is that there s something wrong with the communication channel If the programmer sees a signature like Oxf ff FFF or 0x000000 or the signature changes from one trial to the next you ve most likely got something wired up to your ISP line
68. y some code out of one of the book s projects but the same basic steps apply for when you re writing it yourself 1 2 Start the Arduino IDE Import the header files into the project using the Sketch gt Import Library pulldown where you should find the AVR Programming Library folder at the bottom of the list Notice that the Arduino IDE adds include lines for each header file in your directory Save this mostly blank sketch with a descriptive name This will create a di rectory for you to put your code in Outside of Arduino copy the C code file that you d like to use into the sketches directory If you press Open and reopen the sketch you should see this newly added code in a new tab Alternatively you can write new C code in the sketch by opening up a new tab Ctrl Shift N or from the arrow menuin the top right corner and then entering the code directly Make AVR Programming 6 To make sure that all works click on the Verify button If it does then you re ready to flash the code AVR and the Arduino portpins h and the Arduino IDE The code compiler that the Arduino IDE uses is the same GCC as you d use if you were compiling man ually As such it doesn t care if you pass it code written in C for the AVR or in C using the Arduino libraries Along the way though found a gotcha If you want to compile for an ATmega 328P chip as is found on the Arduino Uno for instance you ll wa

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