Programming an AVR uC

liyf · 发表于 2015-3-1 11:31:24

Programming an AVR uC
The AVR family of `micro-controllers' (uCs) have their own,non-volatile memory; your program and data are safe, even ifall power is lost. These chips also contain most of what is neededto program them. If you connect an AVR to the parallel port of aPC loaded with the right software - a `programmer' - then PC and uCwill happily talk each other through the procedure. Uploading aprogram to the chip takes just a few seconds and very littlehardware. It can even be done while the uC is `in-circuit', sittingin the apparatus you want it to control. A program already in thechip can be erased by the same `programmer'; there is no need forultra-violet light or a special power supply.
So what do you need to program this kind of brain? First of all acomplete description of the device, available from Atmel:

AT90 family data sheets in portable document format (pdf, AdobeAcrobat)

The next item is a language. The obvious choice is assembly. A 110page book about the instruction set (the words of the language andtheir use) is available from Atmel. This book covers the completeAVR (trademark Atmel) instruction set. Check the datasheet for theuC of your choice above to tell you which words you can use. Youcan download the

instruction set in portable document format

An alternative may be C, available as a version ofgcc/binutils:

WindowsAVRGCC
GNU tools voor AVR

Note: the avr-gcc/binutils combination is able to provide Intel Hexfiles, suitable for upload to an AVR uC using sp12. More about thatin the Linux section below.
Or you might prefer a basic-like language, like

FastAVR

If you will be using assembly, then the next thing you want is anassembler, to convert your human-readable assembly into uC-readablemachine code. Tom Mortensen has written a pretty good one, which isavailable for Dos as well as Linux. You'll find it on his page:

http://www.archive.org/details/tucows_7992_tavrasm

Others are freely available from Atmel:

AVR Studio:AVR Studio 4 is the new professional Integrated DevelopmentEnvironment (IDE) for writing and debugging AVR applications inWindows 9x/NT/2000 environments. AVR Studio 4 supports thefollowing AVR development tools: ICE50, JTAGICE, ICE200,STK500/501/502 and AVRISP.
IAR AVR Assembler:Archive Containing the IAR Assembler Version 1.50 for theAVR family of microcontrollers. Fully featured command lineassembler. Includes Linker and Librarian. Compatible with AVRStudio. Documentation inlcluded in PDF format.

A programmer: SP12
The final item on the list is a programmer, to upload the code tothe uC. You will need this no matter what language you use. Aconvenient, fully documented programmer wasn't available, so wewrote one ourselves. Here you have the diagram for a little boardcontaining just a a zip-socket for the uC, perhaps a crystal orresonator (but there will often be an internal RC clock) and veryfew other parts, as used by our programmer:

Note that the parallel ports of modern PC's usually provide a rathermodest voltage, around 3.5V. Quite enough for low voltageAVR uC's, but some devices really do require more, an example beingthe ATMega161.
But the software is just as suitable for `in circuit' programming. In that case, the target board must allow free access to MOSI, MISO, SCK and Reset. A 10K resistor between the reset pin and Vccensures power-on reset and allows sp12 sufficient access:

When using the sp12 `stand alone' programming hardware and a plaincable, the 10K/100N time constant on reset isn't required. The uCdoes its own start-up delay when Vcc goes high, and that works fineif it is powered by the parallel port. But I've noticed that resetdoes fail occasionally if power doesn't switch on cleanly - likewhen an adapter is plugged in to feed a target board. The timeconstant on the reset pin solves that, and also guards againstspurious resets (which occurred when I used the 1200 in a chargingciruit, where relatively high currents were switched).

Ken's `dongle'A short cable connects the board to the Centronics parallel portof a PC. In most cases a plain cable will do well enough, but KenHuntington has designed a nice `dongle' to improve the signalquality and make the programming lines high-Z except when sp12 isactive. The dongle can be part of the cable, and is perfectlytransparent to the software. It has no power requirements, as itreceives its Vcc from the port (and passes it on to a low powertarget board if required). The reset circuit should at least consistof a 10K resistor between Vcc and the uC's reset pin. Here is theschematic:

And a possible layout. Click on it to obtain a black film,suitable for making your own pcb:

Here are photo's of our prototypes. As you can see, a pcb isn'treally necessary:

SP12 software: version 2.1
Sp12 version 2.1 is a serial mode (in-circuit) programmer for theAVR family of microcontrollers. When new AVR uCs arrive, you caneasily add support for them yourself, by adding a plain text entryto the new runtime configuration file _sp12dev. Editing this filealso allows you to customize the way sp12 deals with existinguCs.
Customization means, among other things, that you can define thewrite (high, extended) fuses commands so they won't touch the bitsthat can lock you out of your uC. For instance, the Mega8 and theTiny15 both allow serial mode access to RSTDISBL, which can takeaway the resetpin - thus ending serial mode programming access.The Tiny15 also permits writing to SPIEN. If you use the _sp12deventries as provided, these fuses will never be altered by usererrors.
Sp12 is one of the few programmers capable of uploading newsoftware to several uCs on a single target, in one go. Yet it is a small and simple command line tool, easy to use in scripts andbatch files.

You need version 2.1 if you are going to program the ATtiny2313/V orlater AVR uCs, which come with a new command as part of theirprogramming algorithms. Previous sp12 versions don't know about thenew command, which makes programming uCs which support it unnecessarilyslow. Also, the previous sp12 versions contain a small bug whichmakes it impossible to properly recognize the Tiny2313's devicecode.
You'll find that programming the Tiny2313 is a zippy process, using 2.1.It took my PC about 14 seconds to completely fill the flash of the oldAT90S2313. Uploading the same stuff to the Tiny takes just a littlemore than 1 second!
Version 2.1 has been tested with the AT90S1200(A), ATtiny2313V,AT90S2313, AT90S8515, AT90S4414, AT90S2323, AT90S4434, AT90S8535,AT90S2343, Tiny22L, AT90S2333, AT90S4433, ATtiny15L, ATmega103,ATmega603, ATmega161, ATmega163, ATmega8, ATmega128, among others(uCs we use ourselves), and by others with for instance theMega162, Mega168 and Mega2561.
If after running "sp12 -s" you don't see your AVR uC on the list,you can add support for it yourself by adding a simple plain textentry to _sp12dev. Documentation in the sp12 package (sp12dev.txt) describes how to do it.When you do, please let me knowabout your success or otherwise.
Here is the latest _sp12dev, towhich support has been added for and by:

uC:	author:
Tiny12	Rob van Arem
ATmega16	Arian van Dorsten
ATmega32	Berndt Brandes
Tiny13	Alan Probandt, John Scott
Tiny26	Alan Probandt
ATmega48/V, 88/V and 168/V	Alan Probandt, Jaume Clarens, John Scott
ATmega162	Dirk Küppers
ATmega8535	Andreas Sims
ATmega8515	Christian Spahn
ATtiny861	Rob van Arem
AT90PWM3	Rob van Arem
ATtiny25, 45 and 85	Hubert Weber
ATmega2561	Artur Pundsack
ATmega328P	Malte Marwedel
ATtiny44	Malte Marwedel

Artur Pundsack also added support for the extended address byte tosp12 2.1.1, needed for big uCs like the ATmega2561.
Corrections and confirmations will be appreciated.
Note: Be sure to install sp12 2.1.1 or later before usingthis _sp12dev file, as the entries for the Tiny2313, ATmega2561 andother new uCs makes it unusable for older versions. The total numberof supported AVR uC types is now 39.
March 24 2005: Dirk Küppers adds support for the Mega162, butwrites:

I'm not really sure if the extended fuse write command is correct,because I think the write command from the datasheet is wrong.Low and high fuses tested succesfully.Dirk's version appears correct, but needs confirmation.
Which should be easy:

sp12 -wX1100

To activate BOD with 4.3V as triggerlevel. Then

sp12 -rX

To see whether it reads back properly, and finally reducethe power supply voltage slowly to confirm reset at 4.3V.All entries in de `standard' _sp12dev are written in a common style,but messages can be altered to match a user's preference. Forinstance, Andreas wrote his like this:

FUSES_MESSAGE = 0xxxxxxx - BODLEVEL default (1)FUSES_MESSAGE = x0xxxxxx - BODEN default (1)FUSES_MESSAGE = xx0xxxxx - SUT1 default (1)FUSES_MESSAGE = xxx0xxxx - SUT0 default (0)FUSES_MESSAGE = xxxx0xxx - CKSEL3 default (0)FUSES_MESSAGE = xxxxx0xx - CKSEL2 default (0)FUSES_MESSAGE = xxxxxx0x - CKSEL1 default (0)FUSES_MESSAGE = xxxxxxx0 - CKSEL0 default (1)Quite different from the standard version:

FUSES_MESSAGE = 0xxxxxxx - BODLEVEL 4V (default 2.7V, datasheet p35 p236)FUSES_MESSAGE = x0xxxxxx - brownout detection enabledFUSES_MESSAGE = xxSUxxxx - reset delay, datasheet p28FUSES_MESSAGE = xxxxCKSE - clock select, datasheet p23All features of sp12 version 2.1 are explained insp12.txt. Separatereadme's for each operating system describe the (very simple)installation, and the runtime config files also have their own docs;look for those in the packages below.
Sp12 2.1.2 is compatible with both Linux and BSD thanks to DimitriSokolyuk. Other than that it contains a few bug-fixes.
Those already familiar with earlier versions may want to have a lookat the changes.

Download SP12
Artur Pundsack added support for the extended address byte tosp12 2.1.1 and later, needed for big uCs like the ATmega2561.
The programmer software is available under the GNU General Public Licence.The packages below (self-extracting for Dos/W3x/W9x, gzipped tar forLinux and XP/NT/W2000) contain the source, documentation and an executable.

sp12 v2.1.2 for Linux andBSD; look below for a tip regarding the use of avr-gcc/binutils
The signed MD5 checksum:sp12v2_1_2-Linux_tgz_md5_txt.asc
sp12 v2.1.1 for XP/NT/W2000
sp12 v2.1.1 for Dos and W3x/9x

Problems with unpacking the XP version? Here is the gist of a recentemail conversation:
> > I get a WinZip error when I try to extract files from the> > current (sp12v2_0_7-Win32) distribution for WinXP etc.: > > "error reading header after processing 0 entries".---snip---Thanks, Steven. It seems to get decompressed from .tgz to a .tarfile when I download it, for some reason, and WinZip objects tothat. djtar expands the .tar file OK, though, so I've got round theproblem. It's probably something to do with WinXP SP2, which I'vejust installed. I've not had any problems before.
SP12 and avr-gcc/binutils
For those who (want to) use avr-gcc/binutils to write their AVRprograms: You may have the impression that avr-objcopy is only ableto provide files in Motorola-S format, but Intel Hex (as used bysp12) is also possible. Jason and Carlos told me:

You need to use avr-objcopy.exe and specify the output as ihex like: avr-objcopy -O ihex code.elf code.rom or in a makefile like: BIN = avr-objcopy FORMAT = ihex %rom: %elf $(BIN) -O $(FORMAT) $< $@ This will create the output in ihex.

Diff for free Borland C
On February 1, 2005, Jaume Clarens wrote:

If you like, i have an sp12 sources able to compile using the free borland C under windoze, just let me know. I can provide you a diff file or complete sources.

Thank you Jaume! Here is the diff(against sp12 version 2.1.0),
containing also this usage instruction asan addition to the makefile:

# In order to compile this software under the borland C free compiler # "http://www.borland.com/products/downloads/download_cbuilder.html" # don't use this makefile, just type # "bcc32 -DWIN32 sp12.c init.c flash.c device.c buffer.c eeprom.c winnt.c"

Setup.exe for XP/NT/W2000
On 26 April 2004 I received this email from Dimo Dimov:

Hello Steven,    Here is attached the script (intended for Inno Setup v. 4.2.). It should be deployed in the root subtree, i.e. in the same level with your README files.    The script definately have some points to be refined:
   1. It doesn't check whether "PATH" already contains the path to the current SP12 binaries (neither deletes the corresponding part of PATH on uninstallation)
   2. It doesn't allow a "forced" (re)installation of the driver.
   3. It is not tested on NT 4.0 or Win98/ME. It is only tested on XP, and partially on Win2000    Best regards Dimo

I think that an automated setup would be appreciated by many users,since MSW makes it something of a chore to install sp12.So I agreed to host Dimo's binary, and also the inno-script.Having the source will allow users to study, alter and possiblyimprove his work. That's what happened to sp12 itself.
Note: The source looks like it should be independent of the sp12version number, as long as the base directory is called `SP12_AVR'.Of course 2.0.7 is now obsolete; the installer should be combinedwith sp12 2.1.

How about OpenBSD and FreeBSD?
On the 9th of January 2010 I received this email from Dima Sokolyuk:

Hallo Steven, I have just ported your SP12 programmer to OpenBSD platform and would like to contribute my changes back at you. The essential part is just a few lines long, but I have also done some code cleanup to keep the compiler quiet by replacing strcat() a.o. with strlcat() versions and by renaming `struct logging log' with `struct logging logging' due to collision with math's log() as suggested by compiler. The final code compiles and works fine both at Linux and OpenBSD. Have a nice day, Dima

Gcc can be a bit pedantic, I find. However, these corrections arevery welcome, will appear in the next version and are recommended forthose who want to compile their own sp12 binary. Here are Dima'sdiffs.
On 15 Oct 2002 I received this email from Jean-Marc Zucconi:

Hi, Here the diffs to allow to compile SP12 v.1.0.3 on FreeBSD. As you can see they are really simple. Cheers, Jean-Marc

The diffs are indeed veryminor.

Tips from a user
In July 1999 I received mail from Mike Rudin about his sp12experiences. He included a few tips for other users, and gave mepermission to publish them, including my comments:On Thu, 22 Jul 1999 Mike Rudin wrote:
> Just a word of thanks for publishing SP12 - it worked
> flawlessly when I was doing an AT90S2313 development
> recently. Just the job!
Good to hear :)
> I used it solely for ISP; there was no need to build a
> separate programmer board.ISP/flash is a pretty nice way to program uCs. I don't think Icould ever live with eeproms and zipsockets again!
> I've also appended a few simple notes and suggestions on the> ISP hardware implementation.
> ISP pinout> ==========> I used a 5-pin 0.1 inch header on the target board> (stripboard in my prototype), with a matching socket on the> programming lead.  If you suggest this as an informal
> 'standard' to anyone else, I recommend this pinout, which is
> a neat match to the AVR pinouts (on all AVR variants I've> looked at), while putting Gnd at one end, which is intuitive> in my opinion:>
> 1. Gnd  (marked with a dot or triangle)
> 2. RESET
> 3. SCK
> 4. MISO
> 5. MOSI
> (If you need a COMS as well, this can be an optional pin 6)It does indeed look like the best pinout, for target boardswith their own power source.
> SCK termination
> ===============
> The recommended 22pF + 100ohm termination components need not> be on the target board, they can be soldered to the connector> on the programming lead (at the target end of course).Valid advice in most cases, I think. There are exceptions: I'mmostly using 8-pin modular connectors for my robotic projects(which often need a communication or programming link with aPC). These phone-type connectors are reliable and very easy to(dis)connect, but there is no elegant way to add thetermination cap and resistor. NOTE: When using the new `dongle', you don't need these componentsat all. Actually, only the AT90S1200 seems to really want them,depending on target and parallel port properties. The later AVRshave different, more effective schmitt-trigger inputs. > RESET switch
> ============
> SP12 holds the RESET line at '0' after programming. In my
> target design I could leave the lead connected during target
> operation (the ISP input pins were not used), and I found it> useful to fix a small mechanical switch to the programming> lead, in series with the RESET line. So after programming, I
> could open the switch to start the target, or close it to> reset the target without needing a power cycle.SP12 version 0.7 and later versions have an option to immediatelystart a uC once programming is finished: -T By default, sp12 will leave the Centronics parallel port databits all zero on exit. Command -T1 leaves the reset pin high, so a connected device will start running immediately after sp12 has finished, assuming it uses an external power source. Command -T2 also leaves the `powerbits' (2-6, as shown by progrmmr.gif) high, to run a device without external power.
> Status LED
> ==========
> I needed a status LED in my target design, so I chose to use
> the PB6(MISO) pin to drive it (I chose active-low).  So
> during ISP programming, the LED would flicker to give a
> visible confirmation of progress.An interesting example of double use. The programming pins can often serve other functions as well, but some care must be taken to avoidexcessive loads and conflicts. Be sure to read all relevant documentation.