Atmel SAM9X25, Manual

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853
11054A–ATARM–27-Jul-11
SAM9X25
853
11054A–ATARM–27-Jul-11
SAM9X25
Figure 39-57. Remote Loopback Mode Configuration
39.7.10 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 reset by writing the USART Write Protect Mode Register (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”
Receiver
Transmitter
RXD
TXD
1