How to Use the GY-302 BH1750 Light Intensity Sensor with Arduino

The GY-302 is a breakout board featuring the BH1750 light intensity sensor, which measures light levels in lux. It communicates with microcontrollers via the I2C protocol, making it an excellent choice for light-dependent projects like smart lighting, solar trackers, and photography applications. This tutorial will guide you through connecting and using the GY-302 module with Arduino.

What You Will Need

GY-302 BH1750 Light Sensor Module
Arduino Board (e.g., Uno, Mega, Nano)
Breadboard and Jumper Wires
A computer with the Arduino IDE installed

Step 1: Understanding the GY-302 Module

The GY-302 uses the BH1750 sensor to measure light intensity. It outputs the results in lux, which is the standard unit for measuring illuminance.

GY-302 Pinout

Pin	Function
VCC	Power Supply (3.3V/5V)
GND	Ground
SDA	I2C Data Line
SCL	I2C Clock Line

I2C Address

Default Address: 0x23
Alternate Address: 0x5C (set by pulling the ADDR pin HIGH on some modules)

Step 2: Wiring the GY-302 to Arduino

Connect the GY-302 module to your Arduino as follows:

GY-302 Pin	Arduino Pin
VCC	5V
GND	GND
SDA	A4
SCL	A5

Note: Ensure the correct I2C pins are used for your Arduino board (e.g., SDA and SCL on Arduino Mega are pins 20 and 21).

Step 3: Install the Required Library

To simplify communication with the BH1750 sensor, install the "BH1750" library.

Steps to Install:

Open the Arduino IDE.
Go to Sketch > Include Library > Manage Libraries.
Search for "BH1750" and click Install.

Step 4: Upload the Code

Here’s an example sketch to read light intensity data from the GY-302:

#include <Wire.h>
#include <BH1750.h>

BH1750 lightMeter;

void setup() {
  Serial.begin(9600);
  while (!Serial);

  Serial.println("Initializing BH1750...");

  if (!lightMeter.begin()) {
    Serial.println("BH1750 not detected. Check wiring.");
    while (1);
  }

  Serial.println("BH1750 ready.");
}

void loop() {
  float lux = lightMeter.readLightLevel(); // Read light level in lux

  Serial.print("Light Intensity: ");
  Serial.print(lux);
  Serial.println(" lx");

  delay(1000); // Wait 1 second before the next reading
}

Step 5: Test the Setup

Connect the Arduino to your computer via USB.
Open the Arduino IDE and select the correct Board and Port under the Tools menu.
Upload the code by clicking Upload.
Open the Serial Monitor (Tools > Serial Monitor) and set the baud rate to 9600.
Observe the light intensity readings displayed in lux.

Optional: Adjusting I2C Address

If the default I2C address (0x23) does not work, check the module's ADDR pin configuration. Some modules allow you to switch to an alternate address (0x5C) by connecting the ADDR pin to VCC.

Applications of the GY-302

Smart lighting systems
Solar panel tracking
Light intensity measurement in photography
Indoor and outdoor light monitoring

Troubleshooting

No response from the sensor: Verify the I2C wiring and check the module’s I2C address.
Incorrect readings: Ensure the sensor is not obstructed or receiving light reflections.
Library errors: Confirm that the BH1750 library is correctly installed.

Conclusion

You’ve successfully interfaced the GY-302 BH1750 light sensor with Arduino. This versatile sensor provides accurate light intensity measurements in lux, making it an excellent tool for a variety of light-sensitive projects. Experiment further by integrating it with other components or systems!