Arbor Technology EmETX-i2304, User Manual

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Appendix
Appendix A. Watchdog Timer (WDT) Setting
The application software depends on its requirement to trigger WDT with ad -
equate timer setting. Before WDT timeout, the functional normal system will re -
load the WDT. The WDT never time-out for a normal system. The WDT will not
be reloaded by an abnormal system, then WDT will time-out and auto-reset the
system to avoid abnormal operation.
This computer supports 255 levels watchdog timer by software programming I/O
ports.
Below is an program example to disable and load WDT.
Sample Codes:
#include “math.h”
#include “stdio.h”
#include “dos.h”
#define SIO_INDEX 0x2E /* or index = 0x4E */
#define SIO_DATA 0x2F /* or data = 0x4F */
void main()
{
outportb(sioIndex, 0x87); /* Enable Super I/O */
outportb(sioIndex, 0x87);
outportb(sioIndex, 0x07); /* Select logic device – WDT */
outportb(sioData, 0x07);
outportb(sioIndex, 0x30); /* Enable WDT */
outportb(sioData, 0x01);
outportb(sioIndex, 0xF0); /* Enable WDTRST# Output */
outportb(sioData, 0x80);
outportb(sioIndex, 0xF6); /* Set WDT Timeout value */
outportb(sioData, 0x05);
outportb(sioIndex, 0xF5); /* Set Configure and Enable WDT
timer, Start countdown */
outportb(sioData, 0x32);
outportb(sioIndex, 0xAA); /* Disable Super I/O */
}