/*
 * Program to generate pulse width modulation
 * on PT1
 */
#include "hc12.h"

#define DUTY_CYCLE 0x750
#define PERIOD     0x1000

#define TRUE       1 

main()
{
	/* Turn on timer subsystem */
	TSCR = 0x80;
	/* Set prescaler to 8 */
	TMSK2 = 0x03;

	/* Configure PT1 for OC; bring PT1 low, no int */
	TIOS = TIOS | 0x02;              /* TC1 set for output compare */
	TCTL2 = (TCTL2 | 0x08) & ~0x04;  /* OM1:OL1 = 10 */

	/* Set up OC7 to bring PT1 high, enable int */
	TIOS = TIOS | 0x80;              /* TC7 set for output compare */
	OC7M = OC7M | 0x02;              /* OC7 controls OC1 */
	OC7D = OC7D | 0x02;              /* OC7 brings OC1 high */
	TFLG1 = 0x80;                    /* Clear OC7 flag */
	TMSK1 = TMSK1 | 0x80;            /* Enable OC7 interrupt*/

	enable();                        /* Enable interrupts */

	while (TRUE) ;                   /* Do nothing */
}

@interrupt void toc7_isr(void)
{
	TC1 = TC7 + DUTY_CYCLE;  /* Bring OC1 low after Duty Cycle */
	TC7 = TC7 + PERIOD;      /* Bring OC1 high after Period    */
	TFLG1 = 0x80;            /* Clear OC7 flag */
}

/*      INTERRUPT VECTORS TABLE 68HC12
 */
void toc7_isr();   

void (* const _vectab[])() = {   /* 0x0B10 */
        0,              /* BDLC            */
        0,              /* ATD             */
        0,              /* reserved        */
        0,              /* SCI0            */
        0,              /* SPI             */
        0,              /* Pulse acc input */
        0,              /* Pulse acc overf */
        0,              /* Timer overf     */
        toc7_isr,       /* Timer channel 7 */
        0,              /* Timer channel 6 */
        0,              /* Timer channel 5 */
        0,              /* Timer channel 4 */
        0,              /* Timer channel 3 */
        0,              /* Timer channel 2 */
        0,              /* Timer channel 1 */
        0,              /* Timer channel 0 */
        0,              /* Real time       */
        0,              /* IRQ             */
        0,              /* XIRQ            */
        0,              /* SWI             */
        0,              /* illegal         */
        0,              /* cop fail        */
        0,              /* cop clock fail  */
        (void *)0xff80, /* RESET           */
        };