Chapter 32 Cyclic Redundancy Check (CRC)
MPC5602P Microcontroller Reference Manual, Rev. 4
Freescale Semiconductor
811
32.5.4
CRC Output Register (CRC_OUTP)
32.6
Use cases and limitations
Two main use cases shall be considered:
•
Calculation of the CRC of the configuration registers during the process safety time
•
Calculation of the CRC on the incoming/outgoing frames for the communication protocols (not
protected with CRC by definition of the protocol itself) used as a safety-relevant peripheral.
The signature of the configuration registers is computed in a correct way only if these registers do not
contain any status bit. Assuming that the DMA engine has N channels (greater or equal to the number of
Table 32-4. CRC_CSTAT field descriptions
Field
Description
0:31
CSTAT:
Status of the CRC signature
The CSTAT register includes the current status of the CRC signature. No bit swap and inversion
are applied to this register.
In case of CRC-CCITT polynomial only the16 LSB bits are significant. The 16 MSB bits are tied
at 0b during the computation.
The CSTAT register can be written at byte, half-word or word.
This register can be read and written by the software.
This register can be written only during the configuration phase.
Address: Context 1: Base + 0x000C
Context 2: Base + 0x001C
Access: User read/write
0
1
2
3
4
5
6
7
8
9
10
11
12
13
15
R
OUTP
W
Reset
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
R
OUTP
W
Reset
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Figure 32-7. CRC Output Register (CRC_OUTP)
Table 32-5. CRC_OUTP field descriptions
Field
Description
0:31
OUTP:
Final CRC signature
The OUTP register includes the final signature corresponding to the CRC_CSTAT register value
eventually swapped and inverted.
In case of CRC-CCITT polynomial only the16 LSB bits are significant. The 16 MSB bits are tied at
0b during the computation.
This register can be read by the software.