Atmel XMEGA B, User Manual, Page: 116 / 415

116 XMEGA B [DATASHEET]
8291B–AVR–01/2013
Note: Reserved settings will not give any timeout.

Bit 1 – ENABLE: Enable
This bit enables the WDT. Clearing this bit disables the watchdog timer.
In order to change this bit, the CEN bit in “CTRL – Control register” on page 115 must be written to one at the same time.
This bit is protected by the configuration change protection mechanism, For a detailed description, refer to “Configuration
Change Protection” on page 13 .
 Bit 0 – CEN: Change Enable
This bit enables the ability to change the configuration of the “CTRL – Control register” on page 115 . When writing a new
value to this register, this bit must be written to one at the same time for the changes to take effect. This bit is protected
by the configuration change protection mechanism. For a detailed description, refer to
“Configuration Change Protection”
on page 13 .
10.7.2 WINCTRL – Window Mode Control register

Bit 7:6 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to zero
when this register is written.
 Bit 5:2 – WPER[3:0]: Window Mode Timeout Period
These bits determine the closed window period as a number of 1kHz ULP oscillator cycles in window mode operation.
The typical different closed window periods are found in
Table 10-2 . The initial values of these bits are set by the
watchdog window timeout period (WDWP) fuses, and are loaded at power-on. In normal mode these bits are not in use.
In order to change these bits, the WCEN bit must be written to one at the same time. These bits are protected by the
configuration change protection mechanism. For a detailed description, refer to
“Configuration Change Protection” on
page 13 .
Table 10-2. Watchdog closed window periods
Bit 7 6 5 4 3 2 1 0
+0x01
– – WPER[3:0] WEN WCEN
Read/Write (unlocked) R R R/W R/W R/W R/W R/W R/W
Read/Write (locked) R R R R R R R/W R/W
Initial Value (x = fuse) 0 0 X X X X X 0
WPER[3:0] Group Configuration Typical Closed Window Periods
0000 8CLK 8ms
0001 16CLK 16ms
0010 32CLK 32ms
0011 64CLK 64ms
0100 128CLK 0.128s
0101 256CLK 0.256s
0110 512CLK 0.512s
0111 1KCLK 1.0s
1000 2KCLK 2.0s
1001 4KCLK 4.0s