K60P100M100SF2RM Datasheet, PDF (759/1809 Pages) Freescale Semiconductor, Inc – K60 Sub-Family Reference Manual

Chapter 31 Cyclic redundancy check (CRC)
5. Write a 16-bit seed to CRC[LU:LL]. CRC[HU:HL] are not used.
6. Clear the CTRL[WAS] bit to start writing data values.
7. Write data values into CRC[HU:HL:LU:LL]. A CRC is computed on every data
value write, and the intermediate CRC result is stored back into CRC[LU:LL].
8. When all values have been written, read the final CRC result from CRC[LU:LL].
Transpose and complement operations are performed "on the fly" while reading or
writing values. See Transpose feature and CRC result complement for details.
31.3.2.2 32-bit CRC
Compute a 32-bit CRC with the following steps:
1. Set the CTRL[TCRC] bit to enable 32-bit CRC mode.
2. Program the transpose and complement options in the CTRL register as required for
the CRC calculation. See Transpose feature and CRC result complement for details.
3. Write a 32-bit polynomial to GPOLY[HIGH:LOW].
4. Set the CTRL[WAS] bit to program the seed value.
5. Write a 32-bit seed to CRC[HU:HL:LU:LL].
6. Clear the CTRL[WAS] bit to start writing data values.
7. Write data values into CRC[HU:HL:LU:LL]. A CRC is computed on every data
value write, and the intermediate CRC result is stored back into
CRC[HU:HL:LU:LL].
8. When all values have been written, read the final CRC result from
CRC[HU:HL:LU:LL]. The CRC is calculated bytewise, and two clocks are required
to complete one CRC calculation.
Transpose and complement operations are performed "on the fly" while reading or
writing values. See Transpose feature and CRC result complement for details.
31.3.3 Transpose feature
By default, the transpose feature is not enabled. However, some CRC standards require
the input data and/or the final checksum to be transposed. The user software has the
option to configure each transpose operation separately, as desired by the CRC standard.
The data is transposed "on the fly" while being read or written.
Some protocols use little endian format for the data stream to calculate a CRC. In this
case, the transpose feature usefully flips the bits. This transpose option is one of the types
supported by the CRC module.
K60 Sub-Family Reference Manual, Rev. 6, Nov 2011
Freescale Semiconductor, Inc.
759