15
24
16
0
31
23
7
8
31
8
0
16
15
7
23
24
Figure 31-7. Transpose type 11
NOTE
For 8-bit and 16-bit write accesses to the CRC data register, the
data is transposed with zeros on the unused byte or bytes
(taking 32 bits as a whole), but the CRC is calculated on the
valid byte(s) only. When reading the CRC data register for a
16-bit CRC result and using transpose options 10 and 11, the
resulting value after transposition resides in the CRC[HU:HL]
fields. The user software must account for this situation when
reading the 16-bit CRC result, so reading 32 bits is preferred.
31.3.4 CRC result complement
When CTRL[FXOR] is set, the checksum is complemented. The CRC result complement
function outputs the complement of the checksum value stored in the CRC data register
every time the CRC data register is read. When CTRL[FXOR] is cleared, reading the
CRC data register accesses the raw checksum value.
Chapter 31 Cyclic Redundancy Check (CRC)
K22F Sub-Family Reference Manual , Rev. 3, 7/2014
Freescale Semiconductor, Inc.
679
