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R&S URY-Z1 /Z2 probes - EEPROM investigation

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tv84:
It seems there are a few members that want to play with the EEPROM of their R&S URV5 Millivolt probes.

The EEPROM memory has a 1kB content (with a backup copy at offset 0x400), containing several (I think 7) tables with 16-bit or 24-bit values.

I was asked to have a look at the CRC/checksum that R&S uses to validate the contents integrity, so that people could make some valid changes to the probes EEPROMs.

The mechanism isn't a CRC16, it's a very simple 16-bit checksum (little-endian format) present at offset 0x3FA. To calculate it, one just has to do (no, it's not Python , and should be self-explanatory for someone who wants to patch his EEPROM):


--- Code: ---            byte[] eeprom_file

            ushort sum = 0;
            for (int i = 0; i < 0x3FA; i++)
                sum += eeprom_file[i];

            Console.WriteLine("Checksum: {0}", ~sum & 0xFFFF);

--- End code ---

Enjoy!  :popcorn:



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