Arduino DC Digital Voltmeter

#include <TimerOne.h>

//Define 74HC595 Connections with arduio

const int Data =7;

const int Clock=8;

const int Latch=6;

const int SEG0 =5;

const int SEG1 =4;

const int SEG2 =3;

const int SEG3 =2;

int cc =0;

char Value [4];

const char SegData []={0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,0x7F,0x6F};

//=============================================================

// Setup

//=============================================================

void setup () {

// initialize the digital pin as an output.

Serial . begin(9600);

pinMode ( Data , OUTPUT );

pinMode ( Clock, OUTPUT );

pinMode ( Latch, OUTPUT );

pinMode ( SEG0 , OUTPUT );

pinMode ( SEG1 , OUTPUT );

pinMode ( SEG2 , OUTPUT );

pinMode ( SEG3 , OUTPUT );

//Initialize Display Scanner

cc =0;

Timer1 . initialize (10000); // set a timer of length 100000 microseconds (or 0.1 sec – or 10Hz

=> the led will blink 5 times, 5 cycles of on-and-off, per second)

Timer1 . attachInterrupt ( timerIsr ); // attach the service routine here

}

//=============================================================

// Loop

//=============================================================

void loop () {

char Volt [4];

int Voltage = analogRead ( A0 );

//To get fixed point decimal point we multiply it by 100

Voltage = (500/1024.0) * Voltage ; //Scaling of 0 to 5V i.e. 0 to 1023 to 0 to 10 (in 10 steps)

//Display Voltage on Segments

sprintf ( Volt ,”%04d”, Voltage ); //We get ASCII array in Volt

Serial . println( Volt );

Value [0]= Volt [0] & 0x0F; //Anding with 0x0F to remove upper nibble

Value [1]= Volt [1] & 0x0F; //Ex. number 2 in ASCII is 0x32 we want only 2

Value [2]= Volt [2] & 0x0F;

Value [3]= Volt [3] & 0x0F;

delay(200);

}

//=============================================================

// Generates Bargraph

//=============================================================

void DisplayDigit (char d )

{

int i ;

for( i =0; i <8; i ++) //Shift bit by bit data in shift register

{

if(( d & 0x80)==0x80)

{

digitalWrite ( Data , HIGH );

}

else

{

digitalWrite ( Data , LOW );

}

d = d <<1;

//Give Clock pulse

digitalWrite ( Clock, LOW );

digitalWrite ( Clock, HIGH );

}

//Latch the data

digitalWrite ( Latch, LOW );

digitalWrite ( Latch, HIGH );

}

//===================================================================

// TIMER 1 OVERFLOW INTTERRUPT FOR DISPALY

//===================================================================

void timerIsr ()

{

cc ++;

if( cc ==5) //We have only 4 digits

{ cc =1;}

Scanner ();

TCNT0 =0xCC;

}

//===================================================================

// SCAN DISPLAY FUNCTION

//===================================================================

void Scanner ()

{

switch ( cc ) //Depending on which digit is selcted give output

{

case 1:

digitalWrite ( SEG3 , HIGH );

DisplayDigit ( SegData [ Value [0]]);

digitalWrite ( SEG0 , LOW );

break;

case 2:

digitalWrite ( SEG0 , HIGH );

DisplayDigit ( SegData [ Value [1]] | 0x80); //0x80 to turn on decimal point

digitalWrite ( SEG1 , LOW );

break;

case 3:

digitalWrite ( SEG1 , HIGH );

DisplayDigit ( SegData [ Value [2]]);

digitalWrite ( SEG2 , LOW );

break;

case 4:

digitalWrite ( SEG2 , HIGH );

DisplayDigit ( SegData [ Value [3]]);

digitalWrite ( SEG3 , LOW );

break;

}

}

//===================================================================