57.5.3 Register Write Protection

To prevent any single software error from corrupting TRNG 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 TRNG Write Protection Mode Register (TRNG_WPMR).

If a write access to the protected registers is detected, the WPVS flag in the TRNG Write Protection Status Register (TRNG_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 TRNG_WPSR.

The following register can be write-protected when WPEN is set:

• TRNG_MR

The following registers can be write-protected when WPITEN is set:

• TRNG_IER
• TRNG_IDR

The following registers can be write-protected when WPCREN is set:

• TRNG_CR
• TRNG_PKBCR