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Appendix A Programming the watchdog timer 39
Watchdog Timer Delay Values
Delay Time Value (Hex) Delay Time Value
(Hex)
0 ~ 2 E 16 ~ 18 6
2 ~ 4 D 18 ~ 20 5
4 ~ 6 C 20 ~ 22 4
6 ~ 8 B 22 ~ 24 3
8 ~ 10 A 24 ~ 26 2
10 ~ 12 9 26 ~ 28 1
12 ~ 14 8 28 ~ 30 0
14 ~ 16 7
The following demo program illustrates the programming steps
required to enable, set the time-out interval and disable the
watchdog timer.
#include<stdio.h> #include<dos.h> #include <conio.h> #include
<time.h> #include<graphics.h> void mydelay(void);
/* MAIN PROGRAM */ void main(void) {
unsigned int dog=0,
run_time=0;
char inkey;
clrscr();
gotoxy(15, 6);printf(“AAEON TECHNOLOGY, INC.”);
gotoxy(15, 7);printf(“WATCHDOG TIMER TEST & DEMO
PROGRAM”);
gotoxy(15, 9);printf(“Please setup watchdog delay
time:(2 Sec-30 Sec)”);
/* Set watchdog timer time-out interval */
scanf(“%2d”,&dog); /* Input watchdog timer time-
out interval (Sec) */
dog=dog/2; /* Convert time-out interval
to designated Hex */
dog=15-dog;
outportb(0x443,dog); /* Enable watchdog timer */
/* Setup screen display format */
gotoxy(15,11);printf(“Now enable watchdog!”);
gotoxy(15,12);printf(“You can put keyboard reset or
disable watchdog.”);
gotoxy(15,13);printf(“ [1].Reset watchdog.”);
gotoxy(15,14);printf(“ [2].Disable watchdog.”);
gotoxy(15,15);printf(“ [3].Return to O.S.”);
/* Read key pressed */