NXP Semiconductors K22F series, Reference Manual, Page: 749 / 1407

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Figure 32-4. 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.
32.3.4 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 32 Cyclic Redundancy Check (CRC)
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
NXP Semiconductors 749