Forum Discussion
New ContributorManual checksum verification of CFM0
New ContributorThanks Frank. I noticed there are 2 checksums shown in the programmer, "checksum" and "usercode". When I converted my SOF file into RPD and MAP files, I was able to open the RPD file in a hex editor and locate the UFM section. It was all FFs. I had inserted some customized data into this section with the hex editor, and used the same tool to repack a new POF file, which now contains the customized UFM data and the original CFM and ICB data.
Comparing the original POF to the repacked POF, I don't directly see my customized data in there. (It may be encoded differently or compressed or something, and POF file format is not publicly specified, I understand.). When I load each POF file into the programmer, the "Checksum" is different, consistent with what you are describing. However, the "Usercode" checksum, is still the same, leading me to believe that it applies specifically for the CFM data and not the POF file as a whole. So this is the actual reason why I focused on the usercode checksum; it can remain the same despite different POF file when repacked differently.
So my goal is to understand how the "usercode" checksum works, should that be documented somewhere or if someone knows.
Farabi_AlteraRegular Contributor
Hello,
There might be some confusion here:
Checksum : configuration data checksum, reflect the contents that actually downloaded/configured into CFM. Any changes to the bitstream will change checksum. Usage to detect corruption or mismatch in configuration data.
Usercode : it is NOT the checksum of the POF file. Quartus may default it to something static or left constant. Usercode remains identical is expected behavior. Usage to version tagging/design identification/JTAG bases system identification.
regards,
Farabi- Dennis_Nedry
Cool, that sounds right to me. Do you have any ideas about the method that those checksums are calculated? My guess is that they seem like simple sums of a range of data, but I don't know the correct ranges or word sizes to add up.
- Farabi_Altera
Hello,
I am soryy, this information is treated as confidential. This is built-in inside the Quartus Programmer engine.
Quartus Programmer calculates the checksum by performing a simple byte-wise summation of the binary configuration data programmed to the device, excluding metadata. You can confirm this number by refer to the generated map file.
regards,
Farabi
