#include	<pic.h>
#include  <conio.h>
#include  <stdio.h>

#include "i2cmsu.h"


#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 sinewave using a 64 step  or 16 step table */

/* Uses timer2 */

#define DAC 0x58        /* I2C DAC 01011000 */



#include "sinegen.h"


/* the outer legs of the 10K pot should be hooked up between +5 and 0 */
/* the middle leg (wiper) connected to AN0 */


/* 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);
}

int update_dac(unsigned char val) {
  i2c_WriteTo(DAC);
  i2c_PutByte(0x00);
  i2c_PutByte(val);
  i2c_Stop();
}

char dac_value;
char dac_flag;
char pr_flag;

#define MIN_PERIOD 25
#define MAX_PERIOD 100

// i2c clock freq = Fosc/4(SSPAD+1)
// 100000(SSPPAD+1) = 3686400/4
//  SSPAD = 8.2, use 8, will be close to 100 Khz


/* assumes right justification, only returns most 7 bits,
   limits value between min_period and max_period */

update_period(){

  unsigned char rval1,rval2;
  /* read ADC result, use as period, start new conversion */
  rval2 = ADRESL >> 3; /* lose lower 3 bits */
  rval2 = rval2 & 0x1f; /* mask upper 3 bits */
  rval1 = ADRESH & 0x3; /* mask upper 6 bits */
  rval1 = rval1 << 5; 
  rval1 = rval1 | rval2;
  if (rval1 < MIN_PERIOD) rval1 = MIN_PERIOD;
  if (rval1 > MAX_PERIOD) rval1 = MAX_PERIOD;
  PR2 = rval1;  /* set timer2 period register */
  /* start new conversion */
  bitset(ADCON0, 2); /* start conversion */
}


unsigned char sineptr;
unsigned char tabmax;

void interrupt
timer2_isr(void)
{


  sineptr++;
  if (sineptr == tabmax){
    sineptr = 0;
    pr_flag = 1;
  }
  dac_flag = 1;
  bitclr(PIR1,1);   // 	TMR2IF = 0; clear timer interrupt flag
}



main(void)
{
  char inchar;


  /* configure A/D inputs of PORT A to be all digital inputs */
  ADCON1 = 0x8E;         /* Port A analog input, right justification of result */
  TRISA = 0xFF;		/* all bits input */
  
  /* 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 */

#if 1
  SPBRG = 95;  /* 9600 in high baud rate mode, crystal = 14.7456 Mhz */
#endif


  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 */

  bitset(RCSTA, 4); /* enable recieve */
  

  ADCON0 = 0x80;  /* sampling freq = Fsoc/32, channel 0 */
  bitset(ADCON0,0); /* turn on ADC*/

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

  pr_flag = 0;
  dac_flag = 0;
  sineptr = 0;

  tabmax = 16;
  printf("Enter '1' for 64 entry table, anything else chooses 16 ");
  inchar=getch();
  pcrlf();
  if (inchar == '1') tabmax = 64;

  /* start first conversion. At end of each cycle, do new conversion */

  bitset(ADCON0, 2); /* start conversion */
  while (bittst(ADCON0,2));  /* wait for end of conversion */

  printf("First conversion ");
  pcrlf();
 
  PR2 = MAX_PERIOD;
  if (tabmax == 16)
    update_dac(sine16tab[sineptr]);
  else  update_dac(sine64tab[sineptr]);
 

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

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

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


  printf("Entered Loop ");
  pcrlf();

  // 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(;;) {

    if(dac_flag) {
      if (tabmax == 16)
	update_dac(sine16tab[sineptr]);
      else  update_dac(sine64tab[sineptr]);
      dac_flag = 0;
      if (pr_flag) {
	update_period();
	pr_flag = 0;
      }
      /* now write to DAC */
    }
  }
}





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