29.5.1 Control A


Bit	7	6	5	4	3	2	1	0
	WINDOW[3:0]				PERIOD[3:0]
Access	R/W	R/W	R/W	R/W	R/W	R/W	R/W	R/W
Reset	x	x	x	x	x	x	x	x

Bits 7:4 – WINDOW[3:0] Window

Writing a non-zero value to this bit field enables the Window mode and selects the duration of the closed window.

The bits are optionally lock-protected:

If the LOCK bit in the STATUS register is ‘1’, all bits are change-protected (Access = R)
If the LOCK bit in the STATUS register is ‘0’, all bits can be changed (Access = R/W)

Note: The timing values are provided for an Ultra-Low Power Oscillator frequency of precisely 32.768 kHz. Refer to the Electrical Characteristics section for specific information regarding the accuracy of the Ultra-Low Power Oscillator.

Value	Name	Description
0x0	OFF	-
0x1	8CLK	244 μs
0x2	16CLK	488 μs
0x3	32CLK	977 μs
0x4	64CLK	1.95 ms
0x5	128CLK	3.91 ms
0x6	256CLK	7.81 ms
0x7	512CLK	15.6 ms
0x8	1KCLK	31.2 ms
0x9	2KCLK	62.5 ms
0xA	4KCLK	125 ms
0xB	8KCLK	250 ms
Other	-	Reserved

Bits 3:0 – PERIOD[3:0] Period

Writing a non-zero value to this bit field enables the WDT. In Normal mode, this bit field selects the time-out interval. In Window mode, this bit field selects the open window duration.

The bits are optionally lock-protected:

If the LOCK bit in the STATUS register is ‘1’, all bits are change-protected (Access = R)
If the LOCK bit in the STATUS register is ‘0’, all bits can be changed (Access = R/W)

Note: The timing values are provided for an Ultra-Low Power Oscillator frequency of precisely 32.768 kHz. Refer to the Electrical Characteristics section for specific information regarding the accuracy of the Ultra-Low Power Oscillator.

Value	Name	Description
0x0	OFF	-
0x1	8CLK	244 μs
0x2	16CLK	488 μs
0x3	32CLK	977 μs
0x4	64CLK	1.95 ms
0x5	128CLK	3.91 ms
0x6	256CLK	7.81 ms
0x7	512CLK	15.6 ms
0x8	1KCLK	31.2 ms
0x9	2KCLK	62.5 ms
0xA	4KCLK	125 ms
0xB	8KCLK	250 ms
Other	-	Reserved

Name:	CTRLA
Offset:	0x00
Reset:	From FUSE.WDTCFG
Property:	Configuration Change Protection