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ACS712 Current Sensor Module

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Ekostra Electronics

On April 5, 2025

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ACS712 5A Current Sensor Module

Hall-Effect Based AC/DC Current Measurement for Arduino Projects

Introduction

The ACS712 is a hall-effect based current sensor that can measure both AC and DC currents up to ±5A. It provides analog output proportional to the measured current, making it ideal for energy monitoring, motor control, and over-current protection applications.

Key Features

⚡ Bidirectional

Measures both AC and DC currents

🔌 Easy Interface

Analog output (66mV/A sensitivity)

🛡️ Isolated

2.1kV RMS voltage isolation

📊 Low Noise

80mA output noise typical

Technical Specifications

Current Range	±5A
Sensitivity	185-190mV/A (typical)
Zero Current Output	VCC/2 (2.5V at 5V supply)
Operating Voltage	4.5V – 5.5V DC
Bandwidth	80kHz
Isolation Voltage	2.1kV RMS
Accuracy	±1.5% at 25°C
Dimensions	31mm × 13mm × 10mm

Pin Configuration

Pin	Function	Arduino Connection
VCC	Power Supply (5V)	5V
GND	Ground	GND
OUT	Analog Output	A0
IP+	Current Input +	Load positive
IP-	Current Input –	Load negative

Warning: Do not exceed 5A current or connect directly to mains voltage

Wiring Diagram

// Basic Connections:
// VCC → 5V
// GND → GND
// OUT → A0
// IP+ → Load positive
// IP- → Load negative

// Basic Connections:

// VCC → 5V

// GND → GND

// OUT → A0

// IP+ → Load positive

// IP- → Load negative

Basic Current Measurement

const int sensorPin = A0;
const float mVperAmp = 185.0; // Sensitivity for 5A model
const float vRef = 5.0; // Arduino reference voltage
const int adcResolution = 1023; // 10-bit ADC

void setup() {
  Serial.begin(9600);
}

void loop() {
  float voltage = (analogRead(sensorPin) * vRef) / adcResolution;
  float zeroVoltage = vRef / 2; // 2.5V at no current
  float current = (voltage - zeroVoltage) * 1000 / mVperAmp;
  
  Serial.print("Voltage: ");
  Serial.print(voltage, 3);
  Serial.print("V\tCurrent: ");
  Serial.print(current, 2);
  Serial.println("A");
  
  delay(1000);
}

const int sensorPin = A0;

const float mVperAmp = 185.0; // Sensitivity for 5A model

const float vRef = 5.0; // Arduino reference voltage

const int adcResolution = 1023; // 10-bit ADC

void setup() {

Serial.begin(9600);

}

void loop() {

float voltage = (analogRead(sensorPin) * vRef) / adcResolution;

float zeroVoltage = vRef / 2; // 2.5V at no current

float current = (voltage - zeroVoltage) * 1000 / mVperAmp;

Serial.print("Voltage: ");

Serial.print(voltage, 3);

Serial.print("V\tCurrent: ");

Serial.print(current, 2);

Serial.println("A");

delay(1000);

}

AC Current Measurement

const int samples = 200;
float offset = 2.5; // Zero current voltage (VCC/2)

void setup() {
  Serial.begin(9600);
  // Calibrate zero offset
  float sum = 0;
  for(int i=0; i<samples; i++) {
    sum += analogRead(A0);
    delay(1);
  }
  offset = (sum / samples) * (5.0 / 1023.0);
}

void loop() {
  float maxI = 0, minI = 0;
  
  for(int i=0; i<samples; i++) { float voltage = (analogRead(A0) * 5.0) / 1023.0; float current = (voltage - offset) * 1000 / 185.0; if(current > maxI) maxI = current;
    if(current < minI) minI = current;
    delay(1);
  }
  
  float peakToPeak = maxI - minI;
  float rmsCurrent = peakToPeak / (2 * sqrt(2));
  
  Serial.print("RMS Current: ");
  Serial.print(rmsCurrent, 2);
  Serial.println("A");
}

const int samples = 200;

float offset = 2.5; // Zero current voltage (VCC/2)

void setup() {

Serial.begin(9600);

// Calibrate zero offset

float sum = 0;

for(int i=0; i<samples; i++) {

sum += analogRead(A0);

delay(1);

}

offset = (sum / samples) * (5.0 / 1023.0);

}

void loop() {

float maxI = 0, minI = 0;

for(int i=0; i<samples; i++) { float voltage = (analogRead(A0) * 5.0) / 1023.0; float current = (voltage - offset) * 1000 / 185.0; if(current > maxI) maxI = current;

if(current < minI) minI = current;

delay(1);

}

float peakToPeak = maxI - minI;

float rmsCurrent = peakToPeak / (2 * sqrt(2));

Serial.print("RMS Current: ");

Serial.print(rmsCurrent, 2);

Serial.println("A");

}

Advanced Features

Current Threshold Alert

void checkOverCurrent() {
  float current = getCurrent();
  if(current > 4.0) { // 4A threshold
    digitalWrite(13, HIGH); // Alert LED
    Serial.println("OVER CURRENT!");
  } else {
    digitalWrite(13, LOW);
  }
}

void checkOverCurrent() {

float current = getCurrent();

if(current > 4.0) { // 4A threshold

digitalWrite(13, HIGH); // Alert LED

Serial.println("OVER CURRENT!");

} else {

digitalWrite(13, LOW);

}

Power Calculation

float calculatePower(float voltageSupply) {
  float current = getCurrent();
  return voltageSupply * current;
}

float calculatePower(float voltageSupply) {

float current = getCurrent();

return voltageSupply * current;

}

Moving Average Filter

#define FILTER_SIZE 10
float filterBuffer[FILTER_SIZE];
int filterIndex = 0;

float filteredCurrent(float rawCurrent) {
  filterBuffer[filterIndex] = rawCurrent;
  filterIndex = (filterIndex + 1) % FILTER_SIZE;
  
  float sum = 0;
  for(int i=0; i<FILTER_SIZE; i++) {
    sum += filterBuffer[i];
  }
  return sum / FILTER_SIZE;
}

#define FILTER_SIZE 10

float filterBuffer[FILTER_SIZE];

int filterIndex = 0;

float filteredCurrent(float rawCurrent) {

filterBuffer[filterIndex] = rawCurrent;

filterIndex = (filterIndex + 1) % FILTER_SIZE;

float sum = 0;

for(int i=0; i<FILTER_SIZE; i++) {

sum += filterBuffer[i];

}

return sum / FILTER_SIZE;

}

Troubleshooting

Zero Current Output Not 2.5V

Check power supply voltage (must be 5V)
Allow sensor to warm up for 5 minutes
Calibrate zero offset in software

Noisy Readings

Add 0.1μF capacitor between VCC and GND
Implement software filtering (moving average)
Keep wires short and away from noise sources

Incorrect Current Values

Verify sensitivity value (185mV/A for 5A model)
Check load connections (current must flow through IP+ to IP-)
Ensure proper ground connections

Hotline 24/7

ACS712 5A Current Sensor Module

Introduction

Key Features

⚡ Bidirectional

🔌 Easy Interface

🛡️ Isolated

📊 Low Noise

Technical Specifications

Pin Configuration

Wiring Diagram

Basic Current Measurement

AC Current Measurement

Advanced Features

Current Threshold Alert

Power Calculation

Moving Average Filter

Troubleshooting

Zero Current Output Not 2.5V

Noisy Readings

Incorrect Current Values

Project Ideas

Energy Monitor

Motor Controller

Solar Charger

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