1. XOR operation in CRC calculation example in AD7779 datasheet Rev. 0 http://www.analog.com/media/en/technical-documentation/data-sheets/AD7779.pdf

"The 8-bit CRC polynomial used is x 8 + x 2 + x + 1."

"To generate the checksum, the data is left shifted by eight bits to create a number ending in eight Logic 1s."

"56 bits = chip error + 3 ADC channel bits (010) + 24 data bits (Channel 2) + chip error + 3 ADC channel bits (011) + 24 data bits (Channel 3)"

2. Example from article by Ken Kavanagh an applications engineer in ADI's Precision DAC Group http://www.analog.com/library/analogDialogue/archives/45-02/CRC.html

"The CRC-8 algorithm uses the polynomial C(x) = x8 + x2 + x1 + 1. For x = 2, this is equivalent to the binary value 100000111. To generate the checksum, the 24-bit data is left-shifted by eight bits to create a 32-bit number ending in eight Logic 0s."

So for calculation of CRC based on CRC Polynom 10000011 there will be 64 bits = 56bits + 8 bits of Logic 1s?

In AD7779 datasheet nothing said about 64 bits for CRC calculation, but said "56 bits are used to calculate the 8-bit CRC."

Or CRC Polynom will be 100000111 as in Ken Kavanagh example?

You are fast, we uploaded the calc yesterday

The CRC in the DS is wrong, we are going to update the DS in the coming weeks. Meanwhile, here how to calculate the CRc on the AD7779, the 8MSB should be NOT as the input shift register for the CRC block is set, the data already includes the 8 zero's bits.

Data000001100100111000000000ProcessData

111110010100111000000000Polynomial

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