55.4.5.4 Register Write Protection
To prevent any single software error from corrupting TDES behavior, certain registers in the address space can be write-protected by setting the WPEN (Write Protection Enable), WPITEN (Write Protection Interrupt Enable), and/or WPCREN (Write Protection Control Enable) bits in the TDES Write Protection Mode Register (TDES_WPMR).
If a write access to the protected registers is detected, the WPVS flag in the TDES Write Protection Status Register (TDES_WPSR) is set and the field WPVSRC indicates the register in which the write access has been attempted.
The WPVS flag is automatically cleared by reading TDES_WPSR.
The following register can be write-protected when WPEN is set:
- TDES Mode Register
- TDES Key 1 Word Register x
- TDES Key 2 Word Register x
- TDES Key 3 Word Register x
- TDES Initialization Vector Register x
- TDES XTEA Rounds Register
The following registers can be write-protected when WPITEN is set:
The following register can be write-protected when WPCREN is set: