Information
CRC memory map
Absolute
address
(hex)
Register name
Width
(in bits)
Access Reset value
Section/
page
4003_2000 CRC Data register (CRC_CRC) 32 R/W
FFFF_
FFFFh
30.2.1/
573
4003_2004 CRC Polynomial register (CRC_GPOLY) 32 R/W 0000_1021h
30.2.2/
574
4003_2008 CRC Control register (CRC_CTRL) 32 R/W 0000_0000h
30.2.3/
575
30.2.1 CRC Data register (CRC_CRC)
The CRC Data register contains the value of the seed, data, and checksum. When
CTRL[WAS] is set, any write to the data register is regarded as the seed value. When
CTRL[WAS] is cleared, any write to the data register is regarded as data for general CRC
computation.
In 16-bit CRC mode, the HU and HL fields are not used for programming the seed value,
and reads of these fields return an indeterminate value. In 32-bit CRC mode, all fields are
used for programming the seed value.
When programming data values, the values can be written 8 bits, 16 bits, or 32 bits at a
time, provided all bytes are contiguous; with MSB of data value written first.
After all data values are written, the CRC result can be read from this data register. In 16-
bit CRC mode, the CRC result is available in the LU and LL fields. In 32-bit CRC mode,
all fields contain the result. Reads of this register at any time return the intermediate CRC
value, provided the CRC module is configured.
Address: CRC_CRC is 4003_2000h base + 0h offset = 4003_2000h
Bit 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
R
HU HL LU LL
W
Reset
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
CRC_CRC field descriptions
Field Description
31–24
HU
CRC High Upper Byte
In 16-bit CRC mode (CTRL[TCRC] is 0) this field is not used for programming a seed value. In 32-bit CRC
mode (CTRL[TCRC] is 1) values written to this field are part of the seed value when CTRL[WAS] is 1.
When CTRL[WAS] is 0, data written to this field is used for CRC checksum generation in both 16-bit and
32-bit CRC modes.
Table continues on the next page...
Chapter 30 Cyclic Redundancy Check (CRC)
K20 Sub-Family Reference Manual, Rev. 2, Feb 2012
Freescale Semiconductor, Inc. 573