Amtech Axpert-Eazy Series Instruction Manual page 204

2. Exclusive OR the first 8-bit byte of the message with the low-order byte of the 16-bit CRC register,
putting the result in the CRC register.
3. Shift the CRC register one bit to the right (toward the LSB), zero-filling the MSB. Extract and
examine the LSB.
4. (If the LSB was 0): Repeat Step 3 (another shift). (If the LSB was 1): Exclusive OR the CRC
register with the polynomial value A001 hex (1010 0000 0000 0001).
5. Repeat Steps 3 and 4 until 8 shifts have been performed. When this is done, a complete 8-bit byte
will have been processed.
6. Repeat Steps 2 through 5 for the next 8-bit byte of the message. Continue doing this until all bytes
have been processed.
7. The final contents of the CRC register is the CRC value.
8. When the CRC is placed into the message, its upper and lower bytes must be swapped as
described below.
Placing the CRC into the Message
When the 16-bit CRC (two 8-bit bytes) is transmitted in the message, the low-order byte will be
transmitted first, followed by the high-order byte. For example, if the CRC value is 1241 hex (0001
0010 0100 0001):
Data CRCLo CRCHi
Addr Func Data Data Data Data
Count 41h 12h
10
11
Amtech
11.16