#include <system.h>
#include <memory.h>
#include <rand.h>
#include "srm_p18.h"

#pragma DATA _CONFIG1L, _WDT_OFF_1L & _STVREN_OFF_1L & _XINST_OFF_1L & _DEBUG_OFF_1L;
#pragma DATA _CONFIG1H, _CP0_OFF_1H;
#pragma DATA _CONFIG2L, _FOSC_HS_2L;
#pragma DATA _CONFIG2H, _WDTPS_1024_2H;

#define PROCESSOR_FREQ 25000000
#pragma CLOCK_FREQ PROCESSOR_FREQ

#define Bauds(bval, bmul)  (PROCESSOR_FREQ/((bval)*(bmul)) - 1)&0xFF
#define BAUD57600 Bauds(57600, 4)

#define adc_n(chan) ((((chan)&0xF)<<2) + 0x1)
#define thres(chan) (0xF0 + chan)

typedef unsigned char uchar;

volatile unsigned char count;

volatile char Rcsta   @RCSTA2;
volatile char Txsta   @TXSTA2;
volatile char Baudcon @BAUDCON2;
volatile char Spbrgh  @SPBRGH2;
volatile char Spbrg   @SPBRG2;
volatile char Txreg   @TXREG2;
volatile char Rcreg   @RCREG2;

volatile bit  adc_go  @ADCON0.GO_DONE; // ADC start bit

bool CLEAR@LATC.2; // clear sample and hold
bool LED@LATA.0;   // activity indicator

inline void do_adc(char adc_chan)
{
  adcon0 = adc_n(adc_chan);
  adc_go = 1;
  while(adc_go);
}

char hex2char(char uc)
{
  uc &= 15;  
  uc += '0';
  if(uc>'9') uc +=7;
  return uc;
}

void txchr(char ch)
{
  while(!test_bit(Txsta, TRMT));
  Txreg = ch;
}

void setserial()
{
  Baudcon = 0;
  Baudcon.BRG16 = 1;

  Spbrgh = 0;
  Spbrg = BAUD57600;

  Txsta = 0;
  Txsta.BRGH = 1;
  Txsta.TXEN = 1;

  Rcsta = 0;
  Rcsta.SPEN = 1;

  Rcreg	= 0;
}

void setports()
{
  lata = 0; // disable reference voltage source !!!
  latb = 0;
  latc = 0b00100000; // enable TX
  latd = 0;
  late = 0;
  latf = 0;
  latg = 0;
  lath = 0;
  latj = 0;

  trisa = 0b11101110;  // RefON, LED(Activity)
  trisb = 0b11111111;
  trisc = 0b11000011;  // SDO, ResDAT, ResCLK, CapCLR
  trisd = 0b11111111;
  trise = 0b11111111;
  trisf = 0b11111111;
  trisg = 0b11110101;  // LED(Calibration), TX
  trish = 0b11111111;
  trisj = 0b11111111;
}

void config()
{
  rcon = 0;

  intcon = 0b11010000; // enable peripherial interrupt

  intcon2 = 0;
  intcon2.RBPU = 1;    // disable weak pull_up

  adcon0 = 0b00000001;
  adcon1 = 0b00110000; // external Vref, all AN(0..15) as analog
  adcon2 = 0b10011010; // right justif, Tacq = 6Tad, Fosc/32 (Tad=1.28us)

  cvrcon = 0b11110000; // enable & mount Vthres to output, external Vref

  pie1   = 0;
  pie2   = 0;
  pie3   = 0;
  ipr1   = 0;
  ipr2   = 0;
  ipr3   = 0;
}

void main(void)
{
  setserial();
  setports();
  config();

  count = 0;

  while(1) 
	{
      wdt_reset(); // endless loop
      LED = count.7;
    }
}

void interrupt(void)
{
  if(!intcon.INT0IF) return;

  do_adc(11);

  CLEAR = true;

  short channel;
  MAKESHORT(channel, adresl, adresh);

  channel -= count;

  count += 1;
  count &= 0xF;

  if(count==0) count = 3; // 13 values

  cvrcon = thres(count);

  if(30<=channel&&channel<=1007)
    {
      txchr(':');
      txchr(hex2char(channel>>8));
      txchr(hex2char(channel>>4));
      txchr(hex2char(channel));
      txchr('\r');
    }

  intcon.INT0IF = 0;
  CLEAR = false;
}