Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Freescale Semiconductor/MK21D5WS/CRC/DATAHU#0x0
CRC_DATAHU register.
DATAHU stores the fourth 8 bits of the 32 bit CRC
https://github.com/cmsis-svd/cmsis-svd-data