Datasheet

18.8.1 Control
Name:  CTRL
Offset:  0x0
Reset:  N/A - Loaded from NVM User Row at start-up
Property:  Write-Protected, Enable-Protected, Write-Synchronized
Bit 7 6 5 4 3 2 1 0
ALWAYSON WEN ENABLE
Access
R/W R/W R/W
Reset x x x
Bit 7 – ALWAYSON Always-On
This bit allows the WDT to run continuously. After being written to one, this bit cannot be written to zero,
and the WDT will remain enabled until a power-on reset is received. When this bit is one, the Control
register (CTRL), the Configuration register (CONFIG) and the Early Warning Control register (EWCTRL)
will be read-only, and any writes to these registers are not allowed. Writing a zero to this bit has no effect.
This bit is not enable-protected.
These bits are loaded from NVM User Row at start-up. Refer to NVM User Row Mapping for more details.
Value Description
0
The WDT is enabled and disabled through the ENABLE bit.
1
The WDT is enabled and can only be disabled by a power-on reset (POR).
Bit 2 – WEN Watchdog Timer Window Mode Enable
The initial value of this bit is loaded from Flash Calibration.
This bit is loaded from NVM User Row at start-up. Refer to NVM User Row Mapping for more details.
Value Description
0
Window mode is disabled (normal operation).
1
Window mode is enabled.
Bit 1 – ENABLE Enable
This bit enables or disables the WDT. Can only be written while CTRL.ALWAYSON is zero.
Due to synchronization, there is delay from writing CTRL.ENABLE until the peripheral is enabled/
disabled. The value written to CTRL.ENABLE will read back immediately, and the Synchronization Busy
bit in the Status register (STATUS.SYNCBUSY) will be set. STATUS.SYNCBUSY will be cleared when
the operation is complete.
This bit is not enable-protected.
This bit is loaded from NVM User Row at start-up. Refer to NVM User Row Mapping for more details.
Value Description
0
The WDT is disabled.
1
The WDT is enabled.
Related Links
SAM D21 Family
WDT – Watchdog Timer
© 2018 Microchip Technology Inc.
Datasheet Complete
DS40001882D-page 246