Intel 80C196NU User Manual

10-26

 time_value = epa0_time; /* must read to prevent overrun */
}
void init_timer1()
{
 t1control = 

COUNT_ENABLE 

¦

COUNT_UP 

¦

CLOCK_INTERNAL 

¦

DIVIDE_BY_1;

}

void main(void)
{
 unsigned int time_value;

 /* Initialize the timers and interrupts before using the EPA */
 init_timer1();   
 init_epa0();
 enable();

/*  Globally enable interrupts  */

 while(1);

/*  loop forever, wait for interrupts to occur */

}

This example C program demonstrates the generation of a PWM signal using the EPA’s PWM
toggle mode (see “PWM Modes” on page 6-26) and shows how to service the interrupts with the
PTS. The PWM signal in this example has a 50% duty cycle.

#pragma model(EX)
#include <80c196np.h>
#define   PTS_BLOCK_BASE      0x98

/* Create typedef template for the PWM_TOGGLE mode control block.*/
typedef struct PWM_toggle_ptscb_t {

unsigned char  unused;
unsigned char  ptscon;
void  *pts_ptr;
unsigned int constant1;
unsigned int constant2;
} PWM_toggle_ptscb;

/* This locates the PTS block mode control block in register ram. This */
/* control block may be located at any quad-word boundary. */

register PWM_toggle_ptscb PWM_toggle_CB_3;
#pragma locate(PWM_toggle_CB_3=PTS_BLOCK_BASE)

/* The PTS vector must contain the address of the PTS control block.*/
#pragma pts(PWM_toggle_CB_3=0x3)

/* Sample PTS control block initialization sequence.*/