BQ27742-G1: Checksum for Authentication query

Hi, Riya,

  Please read following section copied from TRM closely, I think it answers your question.

  4.2.5 BlockData(): 0x40 Through 0x5F

This command range is used to transfer data for data flash class access. This command range is the 32-byte data block used to access Manufacturer Info Block A or B. Manufacturer Info Block A is read-only for the SEALED access. UNSEALED access is read-write.

4.2.6 BlockDataCheckSum(): 0x60

The host system must write this value to inform the device that new data is ready for programming into the

specified data flash class and block.

UNSEALED Access: This byte contains the checksum on the 32 bytes of block data read from or written to data flash. The least-significant byte of the sum of the data bytes written must be complemented ([255 –x], for x the 8-bit summation of the BlockData() (0x40 to 0x5F) on a byte-by-byte basis) before being written to 0x60.

SEALED Access: This byte contains the checksum for the 32 bytes of block data written to Manufacturer Info Block A. The least-significant byte of the sum of the data bytes written must be complemented ([255 – x], for x the 8-bit summation of the BlockData() (0x40 to 0x5F) on a byte-by-byte basis) before being written to 0x60.

Thanks!

Phil

Hi Phil,

Thanks . I have already gone through these documents. But I need the method for calculating the checksum . What is meant by 8 bit summation on a byte by byte basis. Can you please explain with an example?

Thanks,

Riya

Hi Riya,

See attached excel file. See if  this helps some.

DataFlash_write.xls