sqwave.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"

#if defined(__18CXX)
void my_gets (char *s);

//return a string from the console
void my_gets (char *s){
 char c;
 
 do {
  c = getche();
  *s = c;
  s++;
  } while (c != '\r');
}
#endif

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

void main(void){

  unsigned int i;

  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 timer 2
  // post scale of 1 
  TOUTPS3 = 0; TOUTPS2 = 0; TOUTPS1 = 0;  TOUTPS0 = 0;

  // pre scale of 4 
  T2CKPS1 = 0;  T2CKPS0 = 1;

  // start timer 2 
  TMR2ON = 1 ;

  // set up PWM 
  PR2 = 255;  // set timer2 PR register 
  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);

  while(1) {

    printf ("Enter PR2 value: ");
#if defined(HI_TECH_C)
    scanf("%d",&i); 
#endif
#if defined(__18CXX)
    {// MCC18 does not have scanf, just get string from console, use atoi
	  char buf[30];
	  my_gets(buf);  // get a string from console
	  i = atoi(buf);  // convert string to integer
	}
#endif	
    pcrlf();
    printf ("New PR2 value is %d ",i);
    pcrlf();
    PR2 =  i ;
    CCPR1L = i >> 1;
    printf ("Enter prescale (1,4,16): ");
#if defined(HI_TECH_C)
    scanf("%d",&i); 
#endif
#if defined(__18CXX)
    {// MCC18 does not have scanf, just get string from console, use atoi
	  char buf[30];
	  my_gets(buf);  // get a string from console
	  i = atoi(buf);  // convert string to integer
	}
#endif
    pcrlf();
    if (i==1) {
      // pre scale of 1
      T2CKPS1 = 0;  T2CKPS0 = 0;
    }
    if (i==4) {
      // pre scale of 4
      T2CKPS1 = 0;  T2CKPS0 = 1;
    }
    if (i==16) {
      // pre scale of 16 
      T2CKPS1 = 1;  
      // T2CKPS0 is a don't care
    }
      

  }
}