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ManualsBrandsNXP SEMICONDUCTORS ManualsMicrocontrollers, Microprocessors & QuartzesEmbedded microcontroller QFN 48 EP (7x7) 32-Bit 50 MHz I/O number 29
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3. Write a 16-bit polynomial to the GPOLY[LOW] field. The GPOLY[HIGH] field is
not usable in 16-bit CRC mode.
4. Set CTRL[WAS] to program the seed value.
5. Write a 16-bit seed to CRC[LU:LL]. CRC[HU:HL] are not used.
6. Clear CTRL[WAS] 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.
30.3.2.2 32-bit CRC
To compute a 32-bit CRC:
1. Set CTRL[TCRC] 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 CTRL[WAS] to program the seed value.
5. Write a 32-bit seed to CRC[HU:HL:LU:LL].
6. Clear CTRL[WAS] 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.
30.3.3 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.
Chapter 30 Cyclic Redundancy Check (CRC)
K20 Sub-Family Reference Manual, Rev. 2, Feb 2012
Freescale Semiconductor, Inc. 575