31.3.1 Register Write Protection
To prevent any single software error from corrupting SFR behavior, certain registers in the address space can be write-protected by setting the WPEN bit or the WPITEN bit in the SFR Write Protection Mode Register (SFR_WPMR).
If a write access to a write-protected register is detected, the WPVS flag in the SFR Write Protection Status Register (SFR_WPSR) is set and the field WPSRC indicates the register in which the write access has been attempted. To read this flag, the SFR peripheral clock must be enabled.
The WPVS bit is automatically cleared after reading the SFR_WPSR.
All registers can be write-protected by setting SFR_WPMR.WPEN.