Datasheet

354
32133D–11/2011
UC3D
Figure 20-23. Remote Loopback Mode Configuration
20.6.7 Write Protection Registers
To prevent single software errors from corrupting USART behavior, certain address spaces can
be write-protected by writing the correct Write Protect KEY and a one to the Write Protect
Enable bit in the Write Protect Mode Register (WPMR.WPKEY, and WPMR.WPEN). Disabling
the write protection is done by writing the correct key, and a zero to WPEN.
Write attempts to a write protected register are detected and the Write Protect Violation Status
bit in the Write Protect Status Register (WPSR.WPVS) is set, while the Write Protect Violation
Source field (WPSR.WPVSRC) indicates the targeted register. Writing the correct key to the
Write Protect KEY bit (WPMR.WPKEY) clears WPVSRC and WPVS.
The protected registers are:
• ”Mode Register” on page 358
• ”Baud Rate Generator Register” on page 368
• ”Receiver Time-out Register” on page 369
• ”Transmitter Timeguard Register” on page 370
Receiver
Transmitter
RXD
TXD
1