Page 315 - Programming Microcontrollers in C

300 Chapter 6 Large Microcontrollers

#include “hc16.h”
#include “gpt.h”
#include “sim.h”

#define PERIOD 0x1000
#define ON_TIME 0x0800
#define GPT_IARB 5
#define GPT_IRL 6
#define GPT_VBA 4

/* function prototypes */
@port void OC3_Isr( void); /* the PWM isr */
WORD pwm_period=PERIOD, pwm_count=ON_TIME;

main()
{
/* The initialization portion of the program */

SYNCR.X=ON; /* set the clock freq to 16.78 MHz */
SYPCR.SWE=OFF; /* disable the watchdog */
GPT_MCR.IARB=GPT_IARB; /* pick an IARB for the Timers */
ICR.IRL=GPT_IRL; /* interrupt level 6 */
ICR.VBA=GPT_VBA; /* vectors start at 0x40 */
OCONM.OCONM3=ON; /* sent OC1 out to pin */
CONM.OCONM5=ON; /* couple OC1 to OC3 */
TMSKON.OC3I=ON; /* enable the OC3 interrupt */
OCOND.OCOND5=ON; /* turn on OC3 when OC1 occurs */
TCTLON.OL3=ON; /* toggle OC3 when OC3 occurs */
TOC1=TCNT+pwm_period;/* set OC1 to the period */
TOC3=TOC1+pwm_count; /* set OC3 time on */
cli(); /* enable the system interrupts */
/* the applications portion of the program */

FOREVER
{
}
}

/* The asynchronous service portion of the program */

@port void OC3_Isr( void) /* the PWM isr */