#include	<pic.h>
#include  <conio.h>
#include <ctype.h>
#include  <stdio.h>
#include  <stdlib.h>     /* must include for atoi */



#define DATA_EEMEM_PROTECT_DISABLE 0x0100
#define XT_OSC 0x0001
#define DISABLE_DEBUG 0x0800

#define CP0		0x1010
#define CP1		0x2020

/* CP0,CP1  code protect off*/
/* other bits zero which means WDT disabled
  Low Voltage prm disabled, brownout disabled
  power up timer enabled */

__CONFIG((CP1 | CP0) | DATA_EEMEM_PROTECT_DISABLE  | XT_OSC | DISABLE_DEBUG);



#define bitset(var,bitno) ((var) |= (1 << (bitno)))
#define bitclr(var,bitno) ((var) &= ~(1 << (bitno)))
#define bittst(var,bitno) (var & (1 << (bitno)))

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


/* return 8 bit char from Recieve port */
char getch ()
{
  unsigned char c;

  /* while (!RCIF) */
  while (!bittst(PIR1,5));  /* check RCIF bit */
	 
  c = RCREG;
  return(c);
}

/* send 8 bit char to Recieve port */
void putch (c)
  char c;

{
  /* wait until transmit reg empty */
  /* while (!TXIF) */
  while (!bittst(PIR1,4));  /* check RCIF bit */
  TXREG = c;
}

     
void pcrlf ()
{
  putch(0x0a);
  putch(0x0d);
}



char tmpbuf[16];

getnum()
{
  char c;
  char i;

  i = 0;
  do {
    tmpbuf[i] = 0;
    c = getch();
    putch(c);
    if (!(isdigit(c)) && (i != 0)) break;
    /* this will skip leading non-digit characters */
    if (isdigit(c)) {
      tmpbuf[i] = c;
      i++;
    }
  }
  while (1);
}


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


update_pwm(){

  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 */
  bitset(ADCON0, 2); /* start conversion */
}


unsigned char do_update_pwm;

void interrupt
timer2_isr(void)
{


  update_pwm();
  bitclr(PIR1,1);   // 	TMR2IF = 0; clear timer interrupt flag
}




main(void)
{

  
  /* setup Async communication */
  bitclr(TXSTA, 6); /* 8-bit transmit */
  bitset(TXSTA, 5); /* transmit enable*/
  bitclr(TXSTA, 4); /* async mode */
  bitset(TXSTA, 2); /* high speed mode */



  bitset(TRISC, 7); /* serial port enable */
  bitset(TRISC, 6); /* serial port enable */
  bitset(RCSTA, 7); /* serial port enable */
  bitclr(RCSTA, 6); /* 8-bit reception */
  /* set baud rate */

  SPBRG = 95;  /* 9600 in high baud rate mode, crystal = 14.7456 Mhz */



  bitset(RCSTA, 4); /* enable recieve */
  
  /* enable I2C */
  
  SSPCON = 0x28;  //Master mode


  //SSPADD = 8;  // close to 100 Khz rate on i2c bus for 3.6864 Mhz
  //SSPADD = 1;  // over 400Khz  for 3.6864 Mhz
  SSPADD = 8;  // about 400Khz  for 14.7456 Mhz, verified to work

  //bitset(SSPSTAT,7); //disable slew rate control for 100 Khz
  bitset(SSPCON,5);  //SSPEN = 1;
  bitset(SSPCON,4);  //CKP = 1;
  bitset(TRISC,3);
  bitset(TRISC,4);  // SDA, SCL pins are inputs


  /* 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 */
  bitset(ADCON0,0); /* turn on ADC*/

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



  /* configure timer 2*/
  /* post scale of 16 */
  bitset(T2CON, 6);
  bitset(T2CON, 5);
  bitset(T2CON, 4);
  bitset(T2CON, 3);

#if 0
  /* pre scale of 4 */
  bitclr(T2CON, 1);
  bitset(T2CON, 0);
#endif

#if 1
  /* pre scale of 16 */
  bitset(T2CON, 1);
  bitset(T2CON, 0);
#endif


  /* start timer 2 */
  bitset(T2CON, 2);

  /* 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 */
  bitclr(TRISC,2);

  /* PWM Mode */
  bitset(CCP1CON, 3);
  bitset(CCP1CON, 2);
  bitclr(CCP1CON, 1);
  bitclr(CCP1CON, 0);

  // enable interrupts 
  bitclr(PIR1,1);   // 	TMR2IF = 0; clear timer interrupt flag
  bitset(PIE1, 1) ;  // enable timer2 interrupt TMR1IE = 1;
  bitset(INTCON,6); /* enable peripheral interrupts, PEIE */
  bitset(INTCON,7); /* enable global interrupts, GIE */



  for(;;) {
    /* let interrupt do all of the work */

  }
}





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