30.5.6 Register Access Protection

All registers with write-access are optionally write-protected by the Peripheral Access Controller (PAC), except the following registers:

• Interrupt Flag Status and Clear register (INTFLAG)

Optional write-protection by the Peripheral Access Controller (PAC) is denoted by the "PAC Write-Protection" property in each individual register description.

When TrustZone is supported (SAM L11 only), all register reads are allowed. Non-secure writes to APB registers are limited as follows. Illegal writes will be ignored.