21.5.16 Register Write Protection

To prevent any single software error from corrupting PIO behavior, certain registers in the address space can be write-protected by setting WPEN and WPITEN in the PIO Write Protection Mode Register (PIO_WPMR) or the PIO Privilege Write Protection Mode Register (PIO_P_WPMR).

If a write access to a User-Accesswrite-protected register is detected, the WPVS flag in the PIO Write Protection Status Register (PIO_WPSR) is set and the field WPVSRC indicates the register in which the write access has been attempted.

If a write access to a privileged-access write-protected register is detected, the WPVS flag in the PIO Privilege Write Protection Status Register (PIO_P_WPSR) is set and the field WPVSRC indicates the register in which the write access has been attempted.

The respective WPVS bit is automatically cleared after reading the PIO_WPSR or PIO_P_WPSR.

The following registers are write-protected when WPEN is set in PIO_WPMR:

• PIO Mask Register
• PIO Configuration Register

The following registers are write-protected when WPEN is set in PIO_P_WPMR:

• PIO Privilege Mask Register
• PIO Privilege Configuration Register
• PIO Privilege Slow Clock Divider Debouncing Register

The following registers are write-protected when WPITEN is set in PIO_WPMR:

• PIO Interrupt Enable Register
• PIO Interrupt Disable Register

The following registers are write-protected when WPITEN is set in PIO_P_WPMR:

• PIO Privilege Interrupt Enable Register
• PIO Privilege Interrupt Disable Register