Data Sheet

128
Atmel | SMART SAM D21 [DATASHEET]
Atmel-42181G–SAM-D21_Datasheet–09/2015
15.8 Register Description
Registers can be 8, 16 or 32 bits wide. Atomic 8-, 16- and 32-bit accesses are supported. In addition, the 8-bit quarters
and 16-bit halves of a 32-bit register, and the 8-bit halves of a 16-bit register can be accessed directly.
Exception for APBASEL, APBBSEL and APBCSEL: These registers must only be accessed with 8-bit access.
Some registers are optionally write-protected by the Peripheral Access Controller (PAC). Write-protection is denoted by
the Write-Protected property in each individual register description. Refer to “Register Access Protection” on page 119
for details.