CNAOB-Communications-Protocol-Notes
CRC CheckSum Algorithm
16-bit CRC verification code
Only 8 data bits are involved in CRC calculation, with the exclusion of start bit and end bit.
Algorithmof CRC code:
1) Presetting a 16-bit register to hex FFFF (namely 1 for all bits in binary system). The register is called CRC register;
2) XORing the first 8-bit binary data (the first byte of the communication message frame) with the low 8-bit of 16-bit CRC register,
then storing the result in
CRC register;
3) Right-shifting the register data by one bit (towards lower bit) and filling the highest bit with 0, then checking the shift-out bit;
4) If the shift-out bit is 0, repeat step 3 (right-shifting one more bit);
If the shift-out bit is1, XOR the CRC register data with polynomial A001 (1010 0000 0000 0001);
5) Repeating step 3 and step 4 until all of the 8-bit data have been processed after 8 right-shift operations;
6) Repeating step 2 to step 5 to process the next byte of the communication message frame;
7) When calculation procedures of the first 5 bytes in the communication message frame are completed, the 16-bit CRC verification
code will be generated in the 16-bit CRC register.