Datasheet

801
SAM9N12/SAM9CN11/SAM9CN12 [DATASHEET]
11063K–ATARM–05-Nov-13
40.7.10 Write Protection Registers
To prevent any single software error that may corrupt USART behavior, certain address spaces can be write protected by
setting the WPEN bit in the USART Write Protect Mode Register (US_WPMR).
If a write access to the protected registers is detected, then the WPVS flag in the USART Write Protect Status Register
(US_WPSR) is set and the field WPVSRC indicates in which register the write access has been attempted.
The WPVS flag is automatically reset by reading the US_WPMR with the appropriate access key (WPKEY).
The protected registers are:
 “USART Mode Register”
 “USART Baud Rate Generator Register”
 “USART Receiver Time-out Register”
 “USART Transmitter Timeguard Register”
 “USART FI DI RATIO Register”
 “USART IrDA FILTER Register”
 “USART Manchester Configuration Register”