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Using Allegro ACS712 DC/AC Current sensor with Arduino Code

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Allegro ACS712 DC/AC Current sensor with Arduino Code

In this page you will get the code for Allegro ACS712 DC/AC Current Sensor. Watch video instruction on how to use ACS712.

Models and Current rating of Allegro ACS712 chip

  1. ACS712ELCTR-05B-T 5A current Sensor
  2. ACS712ELCTR-20B-T 20A current Sensor
  3. ACS712ELCTR-30B-T 30A current Sensor

 * Arduino Sketch for Allegro ACS712 Current Sensor 
 * this sensor can measure current at range of up to 30A
 * It operates with 5V
 * Please watch video instruction and explanation for this code.
 * Written by Ahmad Shamshiri on Sunday Jun 17, 2018 at 22:06 at Ajax, Ontario, Canada
 * for Robojax.com
 * View the video instruction at https://youtu.be/DVp9k3xu9IQ
 * This code has been downloaded from Robojax.com
#define VIN A0 // define the Arduino pin A0 as voltage input (V in)
const float VCC   = 5.0;// supply voltage is from 4.5 to 5.5V. Normally 5V.
const int model = 2;   // enter the model number (see below)

float cutOffLimit = 1.01;// set the current which below that value, doesn't matter. Or set 0.5

          "ACS712ELCTR-05B-T",// for model use 0
          "ACS712ELCTR-20A-T",// for model use 1
          "ACS712ELCTR-30A-T"// for model use 2  
sensitivity array is holding the sensitivy of the  ACS712
current sensors. Do not change. All values are from page 5  of data sheet          
float sensitivity[] ={
          0.185,// for ACS712ELCTR-05B-T
          0.100,// for ACS712ELCTR-20A-T
          0.066// for ACS712ELCTR-30A-T

const float QOV =   0.5 * VCC;// set quiescent Output voltage of 0.5V
float voltage;// internal variable for voltage

void setup() {
    //Robojax.com ACS712 Current Sensor 
    Serial.begin(9600);// initialize serial monitor
    Serial.println("Robojax Tutorial");
    Serial.println("ACS712 Current Sensor");

void loop() {

  //Robojax.com ACS712 Current Sensor 
  float voltage_raw =   (5.0 / 1023.0)* analogRead(VIN);// Read the voltage from sensor
  voltage =  voltage_raw - QOV + 0.012 ;// 0.000 is a value to make voltage zero when there is no current
  float current = voltage / sensitivity[model];
  if(abs(current) > cutOffLimit ){
    Serial.print("V: ");
    Serial.print(voltage,3);// print voltage with 3 decimal places
    Serial.print("V, I: ");
    Serial.print(current,2); // print the current with 2 decimal places
    Serial.println("No Current");

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