Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Atmel/ATSAM3S1C/WDT/CR#0x0
Control Register
Watchdog Restart
Password.
165 (PASSWD): Writing any other value in this field aborts the write operation.
https://github.com/cmsis-svd/cmsis-svd-data