GY-302 BH1750 Digital Light Sensor Module for Arduino 3V-5V

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GY-302 BH1750 Digital Light Sensor Module

High-Precision Ambient Light Sensing for Arduino Projects

Introduction

The GY-302 BH1750 is a digital ambient light sensor that measures illuminance in lux (lx) with high resolution (1-65535 lx). This I2C interface module operates from 3V to 5V and is ideal for automatic brightness adjustment in displays, smart lighting systems, and environmental monitoring.

Key Features

💡 Wide Range

1-65535 lx measurement range

🔍 High Resolution

1 lx resolution at low light levels

🔋 Low Power

0.12mA active current (0.01μA standby)

🌈 Spectral Response

Close to human eye sensitivity

Technical Specifications

Measurement Range 1 – 65535 lx
Resolution 1 lx (at 0-5461 lx range)
Accuracy ±20% (typical)
Supply Voltage 2.4V – 3.6V (5V tolerant I/O)
I2C Address 0x23 (default) or 0x5C (ADDR pin high)
Interface I2C (up to 400kHz)

Pin Configuration

Pin Label Description Arduino Connection
1 VCC Power (3.3V recommended) 3.3V
2 GND Ground GND
3 SCL I2C Clock A5 (Uno) or SCL
4 SDA I2C Data A4 (Uno) or SDA
5 ADDR Address Select GND (0x23) or VCC (0x5C)
Note: Module includes pull-up resistors for I2C lines

Wiring Diagram (Arduino Uno)

// Basic Connections:
// VCC → 3.3V (or 5V with level shifting)
// GND → GND
// SCL → A5 (or SCL)
// SDA → A4 (or SDA)
// ADDR → GND (for default address 0x23)

 

 

Basic Light Measurement

#include 
#include 

BH1750 lightMeter;

void setup() {
  Serial.begin(9600);
  Wire.begin();
  lightMeter.begin(BH1750::CONTINUOUS_HIGH_RES_MODE);
  Serial.println("BH1750 Test");
}

void loop() {
  float lux = lightMeter.readLightLevel();
  Serial.print("Light: ");
  Serial.print(lux);
  Serial.println(" lx");
  delay(1000);
}

 

Library Required: Install “BH1750” by Christopher Laws via Arduino Library Manager

Advanced Configuration

Measurement Modes

// Set different measurement modes
lightMeter.begin(BH1750::CONTINUOUS_HIGH_RES_MODE);  // Default
// Other options:
// CONTINUOUS_HIGH_RES_MODE_2
// CONTINUOUS_LOW_RES_MODE
// ONE_TIME_HIGH_RES_MODE
// ONE_TIME_LOW_RES_MODE

Address Selection

// Use alternate I2C address (ADDR pin to VCC)
BH1750 lightMeter(0x5C);

Measurement Timing

// Adjust measurement time (69 default)
lightMeter.adjustMtreg(138); // Double sensitivity
// Range: 31 (min) to 254 (max)

Power Saving

// Power down sensor between readings
lightMeter.begin(BH1750::ONE_TIME_HIGH_RES_MODE);
// Takes measurement then auto-powers down

Troubleshooting

No Readings

  • Verify I2C connections (SDA/SCL)
  • Check with I2C scanner sketch
  • Confirm power supply (3.3V recommended)

Incorrect Values

  • Ensure proper measurement mode selected
  • Check for light leaks or shadows
  • Calibrate against known light source

Communication Errors

  • Add 4.7kΩ pull-up resistors if missing
  • Reduce I2C clock speed if using long wires
  • Check for address conflicts

Project Ideas

Auto-Brightness Display

Adjusts screen brightness based on ambient light

Smart Lighting

Automatic room light control system

Plant Monitor

Tracks sunlight exposure for plants

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