24.8.1. Control A
Name:
CTRLA
Offset:
0x00
Reset:
Loaded from NVM User Row at startup
Property:
PAC Write-Protection, Enable-Protected, Write-Synchronized
Bit
7
6
5
4
3
2
1
0
ALWAYSON
WEN
ENABLE
Access
R/W
R/W
R/W
Reset
-
-
-
Bit 7 – ALWAYSON: Always-On
This bit allows the WDT to run continuously. After being set, this bit cannot be written to '0', and the WDT
will remain enabled until a power-on Reset is received. When this bit is '1', the Control A register
(CTRLA), 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 '0' to this bit has no effect.
This bit is not Enable-Protected.
This bit is loaded from NVM User Row at startup.
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
This bit enables Window mode. It can only be written if the peripheral is disabled unless
CTRLA.ALWAYSON=1. The initial value of this bit is loaded from Flash Calibration.
This bit is loaded from NVM User Row at startup.
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. It can only be written if CTRLA.ALWAYSON=0.
Due to synchronization, there is delay between writing CTRLA.ENABLE until the peripheral is enabled/
disabled. The value written to CTRLA.ENABLE will read back immediately, and the Enable bit in the
Synchronization Busy register (SYNCBUSY.ENABLE) will be set. SYNCBUSY.ENABLE will be cleared
when the operation is complete.
This bit is not Enable-Protected.
This bit is loaded from NVM User Row at startup.
Atmel SAM L22G / L22J / L22N [DATASHEET]
Atmel-42402E-SAM L22G / L22J / L22N_Datasheet_Complete-07/2016
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