ATXMEGA64A1-CU View Datasheet(PDF) - Atmel Corporation

Part Name

Description

Manufacturer

ATXMEGA64A1-CU

8/16-bit XMEGA A1 Microcontroller

Atmel Corporation 

XMEGA A1

12.3.6

Software reset

The MCU can be reset by the CPU writing to a special I/O register through a timed sequence.

12.4 WDT - Watchdog Timer

12.4.1 Features

12.4.2 Overview

• 11 selectable timeout periods, from 8 ms to 8s.

• Two operation modes

– Standard mode

– Window mode

• Runs from the 1 kHz output of the 32 kHz Ultra Low Power oscillator

• Configuration lock to prevent unwanted changes

The XMEGA A1 has a Watchdog Timer (WDT). The WDT will run continuously when turned on

and if the Watchdog Timer is not reset within a software configurable time-out period, the micro-

controller will be reset. The Watchdog Reset (WDR) instruction must be run by software to reset

the WDT, and prevent microcontroller reset.

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 executed inside the window limits, the microcontroller will

be reset.

A protection mechanism using a timed write sequence is implemented in order to prevent

unwanted enabling, disabling or change of WDT settings.

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.

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8067L–AVR–08/10

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