Pilot Communications SPM93 - Page 41

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with the 16-bit register and shifted 8 times.
9) The content of the 16-bit register is the checksum and is appended to the end of
the packet.
Below is an example to calculate CRC checksum for a hexadecimal byte 6403:
Steps
Byte
Operation
Register
Bit#
Shifts
2
Initial value
1111 1111 1111 1111
1
Load the first data byte
0000 0000 0110 0100
3
XOR
1111 1111 1001 1011
4
Shift 1 bit to right
0111 1111 1100 1101
1
1
5a
XOR generator polynomial
1101 1111 1100 1100
4
Shift 1 bit to right
0110 1111 1110 0110
2
0
4
Shift 1 bit to right
0011 0111 1111 0011
3
0
4
Shift 1 bit to right
0001 1011 1111 1001
4
1
5a
XOR generator polynomial
1011 1011 1111 1000
4
Shift 1 bit to right
0101 1101 1111 1100
5
0
4
Shift 1 bit to right
0010 1110 1111 1110
6
0
4
Shift 1 bit to right
0001 0111 0111 1111
7
0
4
Shift 1 bit to right
0000 1011 1011 1111
8
1
5a
XOR generator polynomial
1010 1011 1011 1110