33.6.8 Register Access Protection

All registers with write-access are optionally write-protected by the peripheral access controller (PAC), except the following registers:

• Control A (CTRLA) register
• Transmit Data (TXDATA) register
• Interrupt Flag Status and Clear (INTFLAG) register
• Scrambling Key (SCRAMBKEY) register

PAC write-protection is denoted by the ‘PAC Write-Protection’ property in the register description.

Write-protection does not apply to accesses through an external debugger.