GY-302 BH1750 Light Intensity Module

What is it?

The BH1750 Light Sensor module (GY-302) is a digital sensor used to measure ambient light intensity in units of lux.

It's commonly used in systems that need to adjust brightness automatically, like smartphones or smart lighting.

How It Works

• The BH1750 sensor detects light using a photodiode

• Converts light into electrical signals

• Internally processes it and outputs a digital lux value

Unlike analog LDRs, it directly gives accurate lux readings (no ADC needed)

Communication Interface

The module uses the I2C protocol.

Pins:

SDA

I2C Address

• Default address: 0x23

• If ADDR pin is HIGH 0x5C

Allows connecting multiple sensors on same bus

Key Specifications

• Measurement range: 1 65,535 lux

• High resolution: 1 lux

• Built-in ADC (16-bit)

• Low power consumption

• Wide voltage support

Working Process

• Sensor detects ambient light

• Converts light electrical signal

• Internal ADC processes signal

• Outputs lux value via I2C

• Microcontroller reads and uses data

Applications

• Automatic ng systems

• Greenhouse light monitoring

• Street light automation

• Camera exposure control

Advantages

• Direct lux output (no calculations needed)

• High accuracy and resolution

• Easy I2C interface

• Low power usage

• Better than LDR for precision

Limitations

• Not ideal for detecting specific light wavelengths

• Slight delay in measurement

• Requires I2C support

Basic Arduino Connection

• VCC 5V

• GND GND

• SDA A4 (Arduino Uno)

• SCL A5 (Arduino Uno)

Example Use

In a smart lighting system:

• Sensor reads ambient light

• If lux < t/p

Practical Tips

• Avoid direct sunlight on sensor for stable readings

• Use proper I2C pull-up resistors (often already included)

• Place sensor where ambient light is representative

BH1750 vs LDR (Quick Comparison)