Athena C10 Communications Manual page 8

In reality, as the device that converts the data to be sent into serial form
(UART) sends the least significant bit (LSB) first instead of the MSB as it
should do for the CRC calculation, the CRC is carried out by inverting the
polynomial. In addition, as the MSB of the polynomial only affects the
quotient and not the remainder, the remainder is eliminated, thus giving
1010000000000001.
The step by step procedure for the CRC16 calculation is as follows:
1) Load a 16-bit register with FFFFh (all bits set to 1).
2) Execute the exclusive OR of the first character with the high order
byte in the register and place the result in the register.
3) Shift the register to the right by one bit.
4) If the bit that left the register on the right (flag) is a 1, execute the
exclusive OR of the polynomial 1010000000000001 with the
register.
5) Repeat steps 3 and 4 eight times.
6) Execute the exclusive OR of the next character with the high order
byte in the register and place the result in the register.
7) Repeat steps 3 to 6 for all the characters in the message.
8) The contents of the 16 bit register are the CRC code that is to be
added to the message.
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