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2010-05-11 by wagnerj@proaxis.com
Hello, Phillipe I did some digging through the IAR docs. In the Linker documentation, it shows you how to generate and view the CRC of various linked modules. And, if you search that same document for "checksum", you will find a description of their checksum algorithm that can be included in code, as in a bootloader. Hope this helps Jim
2010-05-12 by Philippe Habib
Thanks, I got that far too. I can get the CRC placed into the file, and I can read it. My problem is I can't generate one that matches the one in the file. I tried several methods and while they agree with each other, none agree with the IAR one. I've seen the same problem raised in the AVR forum, but the people who've solved it never post the resolution. I'll have to back off and take a fresh look.
On May 11, 2010, at 1:18 PM, wagnerj@proaxis.com wrote: > Hello, Phillipe > > I did some digging through the IAR docs. > > In the Linker documentation, it shows you how to generate and view > the CRC > of various linked modules. And, if you search that same document for > "checksum", you will find a description of their checksum algorithm > that > can be included in code, as in a bootloader. > > Hope this helps > Jim > > > > ------------------------------------ > > Yahoo! Groups Links > > >
2010-05-12 by wagnerj@proaxis.com
Are you comparing an internally generated CRC to the CRC generated by their published algorithm? Or are comparing a CRC generated by their published algorithm against something computed elsewhere? Also, make note of the fact that what is saved in memory MAY be the complement (I think thats it) of the real CRC such that when you run the CRC test over the ENTIRE code (including the CRC), you get some "well-known" value, such as 0x00. Jim
> Thanks, > > I got that far too. I can get the CRC placed into the file, and I can > read it. My problem is I can't generate one that matches the one in > the file. I tried several methods and while they agree with each > other, none agree with the IAR one. > > I've seen the same problem raised in the AVR forum, but the people > who've solved it never post the resolution. > > I'll have to back off and take a fresh look. > > > On May 11, 2010, at 1:18 PM, wagnerj@proaxis.com wrote: > >> Hello, Phillipe >> >> I did some digging through the IAR docs. >> >> In the Linker documentation, it shows you how to generate and view >> the CRC >> of various linked modules. And, if you search that same document for >> "checksum", you will find a description of their checksum algorithm >> that >> can be included in code, as in a bootloader. >> >> Hope this helps >> Jim >> >> >> >> ------------------------------------ >> >> Yahoo! Groups Links >> >> >> > >
2010-05-12 by ecros_technology
--- In AVR-Chat@yahoogroups.com, David Kelly <dkelly@...> wrote: > There is a lot of debate as to > how a CRC should be calculated. I think this is true only in circles where the precise meaning of "CRC" is not understood. The mathematics of cyclic redundancy checks has been extensively studied and optimal solutions exist for just about any situation you can imagine. On the other hand, people are inclined to use the term CRC to mean any kind of redundant data transmitted or stored along with any piece of data that may be received or recovered with errors. A checksum, for example, is much easier to compute than a CRC but offers inferior protection against errors. This, I think, is where the debate happens. Graham.
2010-05-13 by David Kelly
On May 12, 2010, at 10:09 AM, Philippe Habib wrote: > Thanks, > > I got that far too. I can get the CRC placed into the file, and I can > read it. My problem is I can't generate one that matches the one in > the file. I tried several methods and while they agree with each > other, none agree with the IAR one. > > I've seen the same problem raised in the AVR forum, but the people > who've solved it never post the resolution. > > I'll have to back off and take a fresh look. I'm tuning in late but if you are having problems replicating the result of IAR's CRC calculation then perhaps one should ask IAR how the value is calculated? There is a lot of debate as to how a CRC should be calculated. In the past when I studied this issue there was one school of thought that the last bits fed to the CRC generator were weaker than all the other bits previously fed. Their solution was to "close" the calculation by always pushing 0xffff (or some such known value) into the CRC checksum as the very last values added. -- David Kelly N4HHE, dkelly@HiWAAY.net ======================================================================== Whom computers would destroy, they must first drive mad.
2010-06-01 by Jim Wagner
Did this ever get solved? Jim Wagner On May 12, 2010, at 8:09 AM, Philippe Habib wrote: > Thanks, > > I got that far too. I can get the CRC placed into the file, and I can > read it. My problem is I can't generate one that matches the one in > the file. I tried several methods and while they agree with each > other, none agree with the IAR one. > > I've seen the same problem raised in the AVR forum, but the people > who've solved it never post the resolution. > > I'll have to back off and take a fresh look. > > On May 11, 2010, at 1:18 PM, wagnerj@proaxis.com wrote: > > > Hello, Phillipe > > > > I did some digging through the IAR docs. > > > > In the Linker documentation, it shows you how to generate and view > > the CRC > > of various linked modules. And, if you search that same document for > > "checksum", you will find a description of their checksum algorithm > > that > > can be included in code, as in a bootloader. > > > > Hope this helps > > Jim > > > > > > > > ------------------------------------ > > > > Yahoo! Groups Links > > > > > > > > > [Non-text portions of this message have been removed]
2010-06-01 by Philippe Habib
Not yet. I have been buried in an unrelated issue and have not looked at it for a while.
On May 31, 2010, at 6:27 PM, Jim Wagner wrote: > Did this ever get solved? > > Jim Wagner > > On May 12, 2010, at 8:09 AM, Philippe Habib wrote: > >> Thanks, >> >> I got that far too. I can get the CRC placed into the file, and I can >> read it. My problem is I can't generate one that matches the one in >> the file. I tried several methods and while they agree with each >> other, none agree with the IAR one. >> >> I've seen the same problem raised in the AVR forum, but the people >> who've solved it never post the resolution. >> >> I'll have to back off and take a fresh look. >> >> On May 11, 2010, at 1:18 PM, wagnerj@proaxis.com wrote: >> >>> Hello, Phillipe >>> >>> I did some digging through the IAR docs. >>> >>> In the Linker documentation, it shows you how to generate and view >>> the CRC >>> of various linked modules. And, if you search that same document for >>> "checksum", you will find a description of their checksum algorithm >>> that >>> can be included in code, as in a bootloader. >>> >>> Hope this helps >>> Jim >>> >>> >>> >>> ------------------------------------ >>> >>> Yahoo! Groups Links >>> >>> >>> >> >> >> > > > > [Non-text portions of this message have been removed] > > > > ------------------------------------ > > Yahoo! Groups Links > > >
2010-06-01 by Jim Wagner
Thanks Jim On Jun 1, 2010, at 7:37 AM, Philippe Habib wrote: > Not yet. I have been buried in an unrelated issue and have not looked > at it for a while. > > On May 31, 2010, at 6:27 PM, Jim Wagner wrote: > > > Did this ever get solved? > > > > Jim Wagner > > > > On May 12, 2010, at 8:09 AM, Philippe Habib wrote: > > > >> Thanks, > >> > >> I got that far too. I can get the CRC placed into the file, and I > can > >> read it. My problem is I can't generate one that matches the one in > >> the file. I tried several methods and while they agree with each > >> other, none agree with the IAR one. > >> > >> I've seen the same problem raised in the AVR forum, but the people > >> who've solved it never post the resolution. > >> > >> I'll have to back off and take a fresh look. > >> > >> On May 11, 2010, at 1:18 PM, wagnerj@proaxis.com wrote: > >> > >>> Hello, Phillipe > >>> > >>> I did some digging through the IAR docs. > >>> > >>> In the Linker documentation, it shows you how to generate and view > >>> the CRC > >>> of various linked modules. And, if you search that same document > for > >>> "checksum", you will find a description of their checksum > algorithm > >>> that > >>> can be included in code, as in a bootloader. > >>> > >>> Hope this helps > >>> Jim > >>> > >>> > >>> > >>> ------------------------------------ > >>> > >>> Yahoo! Groups Links > >>> > >>> > >>> > >> > >> > >> > > > > > > > > [Non-text portions of this message have been removed] > > > > > > > > ------------------------------------ > > > > Yahoo! Groups Links > > > > > > > > > [Non-text portions of this message have been removed]