TLE5012B
Interfaces
User’s Manual 52 Rev. 1.2, 2018-02
5.4.3 Checksum Nibble Details
The checksum nibble is a 4-bit CRC of the data nibbles including the status nibble. The CRC is calculated using
the polynomial x
4
+x
3
+x
2
+1 with a seed value of 0101. The remainder after the last data nibble is used are
transferred as CRC.
CRC calculation example with SPC interface:
The following example shows the CRC generation for a typical SPC frame with three data nibbles (default setting).
The status nibble is 0000
B
as there are no errors and the slave number is the 00
B
(IFC and SCK pin connected to
ground as shown in the application circuits chapter). The following three data nibbles provide the angle value.
At the beginning the CRC is set at 0000
B
(see Figure 5-18, line 1). The first step to generate the CRC consists in
a XOR logical operation (line 3) between the status nibble (line 1) and the seed value 0101
B
(line 2). Align the
generator polynomial (line 4) to the non-zero MSB of the dataset out of the first step (line 3) and calculate another
XOR (line 5).
Figure 5-17 TLE5012B’s CRC generator polynomial for the SPC interface
From this point onwards, reiterative XOR logical operations between the data (result of the previous operation)
and the generator polynomial are done till the remaining bits are equal or smaller than 0x0F
H
(only 4 bits left).
Figure 5-18 CRC generation example with SPC interface
MSBLSBMSBLSBMSBLSBMSBLSBMSBLSB
1
00000111100100110000
2 Seed
0101
3 XOR
0101
4 Generator polynomial
11101
5 XOR
01000
6 Generator polynomial
11101
7 XOR
01100
8 Generator polynomial
11101
9 XOR
00100
10 Generator polynomial
11101
11 XOR
01111
12 Generator polynomial
11101
13 XOR
00011
14 Generator polynomial
11101
15 XOR
00001
16 Generator polynomial
11101
17 XOR
00001
18 Remainder
0100
20
CRC
4
D
Status-Nibble Data-Nibble 1 Data-Nibble 2 Data-Nibble 3
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