WDT for LPC2148

WDT for LPC2148

Reference user manual :

http://www.keil.com/dd/docs/datashts/philips/user_manual_lpc2119_2129_2194_2292_2294.pdf

/* WDT  [Watch Dog Timer] driver for LPC2129 */

#include <LPC210x.H> /* LPC210x definitions */

extern void init_serial (void); /* Initialize Serial Interface */
extern int sendchar (int ch); /* Write character to Serial Port */
extern int getkey (void); /* Read character from Serial Port */

void feed_watchdog (void) { /* Reload the watchdog timer */
WDFEED = 0xAA;
WDFEED = 0x55;
}

void sendhex (int hex) { /* Write Hex Digit to Serial Port */
if (hex > 9) sendchar('A' + (hex - 10));
else sendchar('0' + hex);
}

void sendstr (char *p) { /* Write string */
while (*p) {
sendchar (*p++);
}
}

/* just waste time here for demonstration */
void do_job (void) {
int i;
for (i = 0; i < 5; i++);
}

int main (void) {
unsigned int i;

init_serial(); /* Initialize Serial Interface */

if( WDMOD & 0x04 ) { /* Check for watchdog time out */
sendstr("Watchdog Reset Occurred\n");
WDMOD &= ~0x04; /* Clear time out flag */
}

WDTC = 0x2000; /* Set watchdog time out value */
WDMOD = 0x03; /* Enable watchdog timer and reset */

for(i = 0; i < 2; i++) {
do_job (); /* the actual job of the CPU */
feed_watchdog(); /* restart watchdog timer */
}

while (1) { /* Loop forever */
do_job (); /* the actual job of the CPU */
/* no watchdog restart,
watchdog reset will occur! */
}
}

 

WDTC:

Watchdog Timer Constant register. This register
determines the time-out value.

WDMOD:

Watchdog Mode register. This register contains the
basic mode and status of the Watchdog Timer.

WDFEED:

Watchdog Feed sequence register. Writing 0xAA
followed by 0x55 to this register reloads the
Watchdog timer to its preset value.