atxmega128a4-mu ATMEL Corporation, atxmega128a4-mu Datasheet - Page 19

• Manufacturer Part Number: atxmega128a4-mu
• Description: Atxmega16a4 8/16-bit Avr Xmega Microcontroller
• Manufacturer: ATMEL Corporation

12.3
12.3.1
12.3.2
8069A–AVR–02/08
WDT - Watchdog Timer
Features
Overview
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The XMEGA A4 has a Watchdog Timer (WDT) that will run continuously when turned on. If the
Watchdog Timer is not reset within a software configurable time-out period, the microcontroller
will reset. To prevent this reset, a Watchdog Reset (WDR) instruction must be run by software to
reset the WDT.
The WDT has a Window mode. In this mode the WDR instruction must be run within a specified
period called a window. Application software can set the minimum and maximum limits for this
window. If the WDR instruction is not run inside the window limits, the microcontroller will be
reset.
For maximum safety, the WDT also has an Always-on mode. This mode is enabled by program-
ming a fuse. In Always-on mode, application software can not disable the WDT.
A protection mechanism is used to prevent unwanted enabling, disabling or change of WDT
settings.
11 selectable timeout period, from 8 ms to 8s.
Two operation modes
Runs from 1 kHz Ultra Low Power clock reference
Configuration lock
– Standard mode
– Window mode
ATxmega A4
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