Appendix Awatchdog Timer; About Watchdog Timer; Sample Program - AXIOMTEK eBOX671A Series User Manual

Embedded system

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eBOX671A Series user's Manual

APPENDIX A

WATCHDOG TIMER

A.1 About Watchdog Timer

Software stability is major issue in most application. Some embedded systems are not watched

by human for 24 hours. It is usually too slow to wait for someone to reboot when computer

hangs. The systems need to be able to reset automatically when things go wrong. The

watchdog timer gives us solution.

The watchdog timer is a counter that triggers a system reset when it counts down to zero from

a preset value. The software starts counter with an initial value and must reset it periodically. If

the counter ever reaches zero which means the software has crashed, the system will reboot.

A.2 Sample Program

#include "stdafx.h"

#include <windows.h>

#include <stdio.h>

#include <tchar.h>

#include <stdlib.h>

#ifdef _DEBUG

#define new DEBUG_NEW

#endif

#pragma comment (lib, "User32.lib" )

#define IDT_TIMER WM_USER + 200

#define _CRT_SECURE_NO_WARNINGS 1

#define setbit(value,x) (value |=(1<<x))

#define clrbit(value,x) (value &=~(1<<x))

HINSTANCE hinstLibDLL = NULL;

Watchdog Timer

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