checcksum calculation using IAR v6 and stm32

lowpowermcu · ‎2011-08-06

Posted on August 06, 2011 at 13:31

Dear STM32 users,

I want to add a checksum to my application in such way I can every let's say 100 seconds check the flash integrity using CRC.

I have found that IAR simplifies this task and can add at the final adress (or other specified locations) the CRC of the application.

I refer to the techical note 11927 Checksum calculation with IELFTOOL after linking with ILINK

http://supp.iar.com/Support/?note=11927&from=search+result

and the provided examples:

http://supp.iar.com/FilesPublic/SUPPORT/003588/Check_Sum_511.zip

I am following the steps in this tech note and I stuck here:

Add usage of the symbol __checksum in your application

In fact I don't understand what does mean ''add usage of the symbol......''

When I declare it as following:

unsigned short __checksum;

I got thsi error message:

Error[Li006]: duplicate definitions for ''__checksum''; in ''C:\.....\checksum\Obj\main.o'', and ''Place holder __checksum''

When I declare it as following as done in the example provided by IAR:

extern unsigned short __checksum;

I got this error message:

ielftool error: The string '__checksum' was not found in the string table

Is there someone who can help me on this? and thank you in advance.

PS: I am using the IAR v6

MCU LÃ¼fter

Fristedt.Jan · ‎2011-08-08

Posted on August 08, 2011 at 10:26

I have no experience with the IAR tools but if your output files are Intel hex it's easy to patch them with the CRC manually.

I think you should use a 32 bit checksum instead of a 16 bit which is really a bit short for the memory size of the STM32.

There is a CRC unit in the STM32 that you can use. It's described in RM0008 section 3.

lowpowermcu · ‎2011-08-09

Posted on August 09, 2011 at 16:28

Hi jan,

I will use crc 32-bit embedded in STM32 but now I am stuck how to generate the CRC using IAR v6.

Any help is welcome.

MCU Lüfter

tbenson · ‎2011-08-09

Posted on August 09, 2011 at 18:47

Here are the settings I used in IAR to get the checksum to match the STM32-generated one (note that your addresses will be different depending on your application):

Also see http://supp.iar.com/Support/?Note=11927

lowpowermcu · ‎2011-08-09

Posted on August 09, 2011 at 21:39

Hi benson,

In ''http://supp.iar.com/Support/?Note=11927'' I don't understand what does mean ''add usage of the symbol......''

When I declare it as following:

unsigned short __checksum;

I got thsi error message:

Error[Li006]: duplicate definitions for ''__checksum''; in ''C:\.....\checksum\Obj\main.o'', and ''Place holder __checksum''

When I declare it as following as done in the example provided by IAR:

extern unsigned short __checksum;

I got this error message:

ielftool error: The string '__checksum' was not found in the string table

How did you get off of it?

Thank you

MCU Lüfter

tbenson · ‎2011-08-09

Posted on August 09, 2011 at 22:54

Make sure you add the __checksum symbol to the Input dialog as shown below:

I'm heading out for vacation now, so good luck :)

lowpowermcu · ‎2011-08-10

Posted on August 11, 2011 at 00:23

Hi benson,

I am really thankfull for your help.

Thanks again benson.

MCU Lüfter