This arduino projects show how to make voltmeter with your arduino. It use voltage divider concept to estimate the voltage input.
Instruction;
1) Connect all jumper wire as shown in diagram.
Upload this code to your arduino
/*
Voltmeter
Voltmeter base on voltage divider concept.
Code based on: http://www.clarenceho.net:8123/blog/articles/2009/05/17/arduino-test-voltmeter
Coded by: arduinoprojects101.com
*/
// include the library code:
#include <LiquidCrystal.h>
// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(7, 8, 9, 10, 11, 12);
// variables for input pin and control LED
int analogInput = 1;
float vout = 0.0;
float vin = 0.0;
float R1 = 50000.0; // !! resistance of R1 !!
float R2 = 4400.0; // !! resistance of R2 !!
// variable to store the value
int value = 0;
void setup(){
// declaration of pin modes
pinMode(analogInput, INPUT);
// set up the LCD's number of columns and rows:
lcd.begin(16, 2);
lcd.print("Vin=");
}
void loop(){
// read the value on analog input
value = analogRead(analogInput);
vout = (value * 5.0) / 1024.0;
vin = vout / (R2/(R1+R2));
// print result to lcd display
lcd.setCursor(4, 0);
lcd.print(vin);
lcd.print("V");
// sleep...
delay(500);
}
Read more: Arduino Voltmeter Code