Arduino voltmeter using an MCP3421 18 bit ∆-∑ ADC

MCP3421_test.pde

/*

This revision includes the modified display output to the LCD

mcp adress = 0x68
 
sr= Sample Rate Selection 
sr=0  ; 00 = 240 SPS (12 bits),
sr=1  ; 01 = 60 SPS (14 bits),
sr=2  ; 10 = 15 SPS (16 bits),
sr=3  ; 11 = 3.75 SPS (18 bits)

pga=  PGA Programmable Gain Amplifier Selector 
0 = 1 V/V,
1 = 2 V/V,
2 = 4 V/V,
 
******--MCP.init(address,sr,pga);--****** 
 
 */



#include <Wire.h>
#include "MCP3421.h" 
MCP3421 MCP = MCP3421();
#include <LiquidCrystal.h>

LiquidCrystal lcd(7, 8, 9, 10, 11, 12);

//int pinVCC=17;  // pin A3 used as + Powersupply for ADC
//int pinGND=16;  // pin A2 used as GND Powersupply for ADC
int pinLed=13;

char st1[20];

long l1;
double vin;
float f1;

void setup(void)
{
  lcd.begin(16,2);

  //pinMode(pinVCC,OUTPUT);  //Not Necessary unless you want to use the analog
  //pinMode(pinGND,OUTPUT);  //pins as a power supply output for the ADC
  pinMode(pinLed,OUTPUT);

  //digitalWrite(pinVCC,1);  // switch on pin for MCP3421 5 volt powersupply

  lcd.print("ADC MCP 3421");  // just to be sure things are working
  Wire.begin();
  delay(1000);
  lcd.setCursor(0,1);
  lcd.print("begin");
  delay(2000);
  lcd.clear();

  MCP.init(0x68,3,0);


}

void loop(void)
{


  while(MCP.ready()==0);

  digitalWrite(pinLed,1);
  vin=MCP.getDouble();
  f1=vin;
  analogRead(0);
  delay(10);
  int v1=analogRead(0);
  int calibration=map(v1,0,1023,0,255);
  float prescale=(calibration*0.01);
  lcd.setCursor(1,0);
  float voltage=(f1*(11+prescale));
  float q=abs(voltage);
    if (q>=10.0){
      lcd.setCursor(2,0);
      lcd.print(q,2);
    }else{
      lcd.setCursor(2,0);
      lcd.print(q,3);
 

  digitalWrite(pinLed,0);

  delay(200);


}




//******************************************************************************************
void sprintDouble( char *str, double val, byte precision){
  // prints val with number of decimal places determine by precision
  // precision is a number from 0 to 6 indicating the desired decimial places
  // example: lcdPrintDouble( 3.1415, 2); // prints 3.14 (two decimal places)
  char st2[16];
  unsigned long frac;
  unsigned long mult = 1;
  int mant= int(val);
  byte padding = precision -1;
  byte sgn=0;

  sprintf(str,"");
  if (val < 0)  sprintf(str,"-");
  mant=abs(mant);
  sprintf(st2,"%d",mant); //prints the int part
  strcat(str,st2); 

  if( precision > 0) {
    strcat(str,".");

    while(precision--)
      mult *=10;

    if(val >= 0)
      frac = (val - int(val)) * mult;
    else
      frac = (int(val)- val ) * mult;
    unsigned long frac1 = frac;
    int cnt=precision;
    // while( frac1 /= 10 )
    while( frac1 = frac1 / 10 & cnt--  ) 
      padding--;
    while(  padding--)  strcat(str,"0");
    sprintf(st2,"%ld",frac);



    strcat(str,st2);



  }

}

where is the "MCP3421.h" file ?