18.4.5 Completing the PIC32 Checksum Calculation

The values derived in previous sections (PF, BF, DCR, DIR) are used to calculate the checksum value. Perform the 32-bit summation of the PF, BF, DCR and DIR as derived in previous sections and store it in a variable, called temp.

The following are the steps of the checksum calculation process:
  1. First, temp = PF + BF + DCR + DIR, which translates to:
    1. temp = 0x7F80000 + 0x002FC010 + 0x000003D6 + 0x00000083
  2. Adding all four values results in temp being equal to 0x0827C469
  3. Finally, the 2’s complement of the temp is the checksum:
    • Checksum = 2’s complement (temp), which is Checksum = (1’s complement (temp)) + 1, resulting in 0xF7D83B97