Hyundai N700E Instruction Manual page 113

N700E INSTRUCTION MANUAL
16bit CRC generation
The step of CRC generation is as follows:
1. All of 16-bit register is 1.0xffff
2. The exclusive OR of 16-bit register and 8-bit register.
3. Shift right side 1bit 16-bit register
4. If the result of step 3 is 1, exclusive OR 16-bit register and 0xa001.
5. Execute 8 times step 3 and step 4.
6. Execute step 2∼6 until data completion.
7. Exchange the step 6 result of higher 8bit and lower 8bit.
Ex) The case of D01 output frequency reading.
Byte 1
Communication
Number
0x01
The sequence of addition Byte(01x01)
16-BIT REGISTER
(Exclusive OR)
01
Shift 1
Shift 2
Polynomial
Shift 3
Shift 4
Polynomial
Shift 5
Shift 6
Polynomial
Shift 7
Shift 8
Polynomial
Byte 1~6
Change upper and lower 8 bit of result 0x36d4 : 0xd436
Byte7 : Upper 8 bit of CRC = 0xd4
Byte8 : Lower 8 bit of CRC = 0x36
Byte 2 Byte 3
Command
0x03 0x01
MSB
1111 1111
0000 0001
1111 1111
0111 1111
0011 1111
1010 0000
1001 1111
0100 1111
0010 0111
1010 0000
1000 0111
0100 0011
0010 0001
1010 0000
1000 0001
0100 0000
0010 0000
1010 0000
1000 0000
CRC of operation results
0x01
0x03
0x01
0x01
0x00
0x01
Byte 4
Parameter
0x01
Flag
1111 1111
1111 1110
1111 1111
1111 1111 1
0000 0001
1111 1110
1111 1111
1111 1111 1
0000 0001
1111 1110
1111 1111
1111 1111 1
0000 0001
1111 1110
1111 1111
0111 1111 1
0000 0001
0111 1110
0x807e
0x3364
0x30e1
0x8831
0xd449
0x36d4
9-6
Byte 5 Byte 6
Parameter number
0x00 0x01