/*
  FILE: MAX158E.C
  DESC:	ACQUIRE FROM MAX158 AND PLOT NB: 0.1 SEC SAMPLING RATE
*/

#include<stdio.h>
#include<dos.h>
#include<stdlib.h>
#include<conio.h>
#include<process.h>
#include<graphics.h>
#include<math.h>

void interrupt (*oldvect)(void);
void interrupt myInterrupt(void);
void drawAxis(void);

long count = 0;

#define VREF  2.5
#define pixelsPerSecond 60.0  /* 600 pixels / 10.0 sec */
#define offsetX 30.0
#define pixelsPerVolt 133.33  /* 400 pixels / 3.0 V */
#define offsetY 425.0

int main(void)
{
  int   channel, desiredChannel;
  float outputVoltage;
  int   outputVoltageInPixels;
  int   baseAddress;
  int   AIN1, AIN2, AIN3, AIN4, AIN5, AIN6, AIN7, AIN8;
  int   data;
  FILE* fp;
  int  i = 0;
  long  oldCount = 0, newCount = 0;
  float updateRateInSeconds;
  float timePastInSeconds;
  int   timePastInPixels;
  int   updateRateInTicks;

  fp = fopen("data.txt", "wt"); /* open for ASCII write */

  baseAddress = 608;

  AIN1 = 0;	AIN5 = 4;
  AIN2 = 1;     AIN6 = 5;
  AIN3 = 2;     AIN7 = 6;
  AIN4 = 3;     AIN8 = 7;

  desiredChannel = 1;

  switch(desiredChannel)
  {
    case 1  : channel = AIN1; break;
    case 2  : channel = AIN2; break;
    case 3  : channel = AIN3; break;
    case 4  : channel = AIN4; break;
    case 5  : channel = AIN5; break;
    case 6  : channel = AIN6; break;
    case 7  : channel = AIN7; break;
    case 8  : channel = AIN8; break;
    default : channel = 999; break;
  }

  updateRateInSeconds = 0.1; /* acquire data every 0.1 sec */
  /*
     18.2 ticks = 1 second.
     1 tick = 0.055 seconds
  */
  updateRateInTicks = (int)(updateRateInSeconds*18.2);

  drawAxis(); /* draw axis and tick marks */

  oldvect = getvect(0x1C); /* save old interrupt vector */
  setvect(0x1C, myInterrupt); /* install my interrupt handler */

  do
  {
     if(!(count % updateRateInTicks))
     {
	/* loop entered whenever count is integer multiple of
	   updateRateInTicks.  In other words, timePastInSeconds
	   is printed out every updateRateInSeconds */
	newCount = count;
	timePastInSeconds = (float)(count/18.2);
	if(oldCount != newCount)
	  {
	    /* acquire ADC sample */
	    data = adc_convert(baseAddress, channel);
	    outputVoltage = (float)((data/255.0)*2.5);
	    /* plot outputVoltage */
	    timePastInPixels = (int)(offsetX + (timePastInSeconds * pixelsPerSecond));
	    outputVoltageInPixels = (int)(offsetY - (pixelsPerVolt*outputVoltage));
	    lineto(timePastInPixels, outputVoltageInPixels);
	    outtextxy(timePastInPixels, outputVoltageInPixels, "*");
	    /* fprintf(fp, "%f\t%f\n", timePastInSeconds, outputVoltage); */
	  }
	oldCount = count;
     }
  } while( timePastInSeconds <= 10.0 );

  fclose(fp);
  setvect(0x1c, oldvect); /* set the old interrupt handler back */

  while(!kbhit()) {};
  closegraph();
  printf("count = %ld, timePastInSeconds = %f", count, timePastInSeconds);
  return 0;

} /* end of main */

int adc_convert(int address, char chan_num)
{
  int dataRead;

  outportb(address, chan_num);
  dataRead = inportb(address);
  return(dataRead);

} /* end of adc_convert */

void interrupt myInterrupt(void)
{
   count++;
   oldvect();
}; /* end of myInterrupt */

void drawAxis(void)
{
  int gdriver, gmode, errorCode;
  int x, y;
  int deltaX = 60; /* horizontal pixels */
  int deltaY = 40; /* vertical pixels */
  int i = 0;
  float j = 3.0;
  char temp[10];

  gdriver = DETECT; /* auto detect graphics card */
  initgraph(&gdriver, &gmode, "C:\\TC"); /* directory contains *.BGI files */
  errorCode = graphresult();

  if(errorCode != grOk) {
    printf("Graphics error %s\n", grapherrormsg(errorCode));
    exit(0);
  };

  setcolor(WHITE);

  /* X-axis setup */
  line(30,425,630,425); /* X-axis line */
  outtextxy(320,450, "Time [s]");
  /* Tick marks every deltaX = 60 pixels. 1 Tick mark = 1 second */
  for(x=30; x<=630; x=x+deltaX) {
    line(x,425,x,430);
    sprintf(temp, "%d", i);
    outtextxy(x,435, temp);
    i = i + 1;
  };

  /* Y-axis setup */
  line(30,25,30,425); /* Y-axis line */
  outtextxy(0,5, "Volts");
  /* Tick marks every deltaY = 40 pixels. 1 Tick mark = 0.3 V */
  for(y=25; y<=425; y=y+deltaY) {
    line(30,y,25,y);
    sprintf(temp, "%1.1f", j);
    outtextxy(0,y, temp);
    j = j - 0.3;
  };
  putpixel(offsetX, offsetY, WHITE);

} /* end of drawAxis */