ledpwm.c

* Use 10 MHz crystal frequency. * Use Timer0 for ten millisecond looptime. * Blink "Alive" LED e

#include "config.h"

#include "serial.c"
#include "serio.c"

// generates a PWM square wave using timer 2 and the CCP module //

// reads A/D value and uses this as PWM value //
// assumes LEFT JUSTIFICATION //


void update_pwm(void){

  unsigned char rval1;

  rval1 = ADRESH;
  CCPR1L = rval1;
  rval1 = ADRESL;
  if (bittst(rval1,7))   bitset(CCP1CON, 5);
      else bitclr(CCP1CON, 5);

  if (bittst(rval1,6))  bitset(CCP1CON, 4);
      else bitclr(CCP1CON, 4);
  // start new conversion //
  GODONE = 1; // start conversion //
}


unsigned char do_update_pwm;

#if defined(HI_TECH_C)
void interrupt timer2_isr(void)
#endif
#if defined(__18CXX)
#pragma interrupt timer2_isr
void timer2_isr(void)
#endif
{
  update_pwm();
  TMR2IF = 0; // clear timer2 interupt flag //
}


void main(void){

  serial_init(95,1); // 19200 in HSPLL mode, crystal = 7.3728 MHz 
  if (POR == 0){  // bit 2 in RCON register, cleared to 0 on power-up reset
    POR = 1;  // setting to bit to 1 means that will remain a '1' for MCLR reset
    printf("Power-on reset has occurred.");
    pcrlf();
  }
  if (TO == 0) {
    SWDTEN = 0; // disable watchdog timer
    printf("Watchdog timer reset has occurred, press reset to recover.\n");
    pcrlf();
    while(1);
  }
  SWDTEN = 1;  // enable watchdog timer

  
  // configure A/D inputs of PORT A to be all digital inputs //
  ADCON1 = 0x0E;         // Port A analog input, left justification of result //
  TRISA = 0xFF;		// all bits input //

  ADCON0 = 0x80;  // sampling freq = Fsoc/32, channel 0 //
  ADON = 1; // turn on ADC

  printf("ADC is configured!!!");
  pcrlf();

  // configure timer 2//

  // pre scale of 16 
  T2CKPS1 = 1;  
  // start timer 2 
  TMR2ON = 1 ;

  // set up PWM //
  PR2 = 255;  // set timer2 PR register, always set for 225 for this choice //
  CCPR1L = (255 >> 1);     // 50% duty cycle //
  bitclr(CCP1CON, 5);
  bitclr(CCP1CON, 4);

  // set CCP1 output 
  TRISC2 = 0;

  // PWM Mode 
  bitset(CCP1CON, 3);
  bitset(CCP1CON, 2);

  // enable interrupts
  IPEN = 0;  // priorities disabled //
  TMR2IF = 0; // clear timer2 interupt flag //
  TMR2IE = 1;   // receive interrupt enable //
  PEIE = 1;  
  GIE = 1;  

  while(1) {
    // let interrupt do all of the work //
    CLRWDT();     //asm("clrwdt"); 
  }
}


//for MCC18, place the interrupt vector goto
#if defined(__18CXX)
#if defined(HIGH_INTERRUPT)
#pragma code HighVector=HIGH_INTERRUPT
#else
#pragma code HighVector=0x0008  
#endif
void HighVector (void)
{
    _asm goto timer2_isr _endasm
}
#pragma code
#endif