How to Use BH1750: Examples, Pinouts, and Specs

Introduction

The BH1750 is a digital light sensor manufactured by ROHM Semiconductor. It is designed to measure ambient light intensity in lux, providing precise and reliable readings. The sensor communicates via the I2C protocol, making it easy to integrate into microcontroller-based systems. Its compact design and low power consumption make it ideal for a wide range of applications.

Explore Projects Built with BH1750

Use Cirkit Designer to design, explore, and prototype these projects online. Some projects support real-time simulation. Click "Open Project" to start designing instantly!

Bluetooth Audio Receiver with Battery-Powered Amplifier and Loudspeakers

This circuit is a Bluetooth-enabled audio system powered by a rechargeable 18650 Li-ion battery. It includes a TP4056 module for battery charging and protection, a PAM8403 amplifier with volume control to drive two loudspeakers, and a Bluetooth audio receiver to wirelessly receive audio signals.

Open Project in Cirkit Designer

ESP32-Based Smart Environmental Monitoring System with BH1750 and DHT22 Sensors

This circuit features an ESP32 microcontroller interfaced with a BH1750 light sensor, a DHT22 temperature and humidity sensor, and two LD2410C radar sensors. The ESP32 collects environmental data from the sensors and can communicate with the radar sensors via UART for motion detection.

Open Project in Cirkit Designer

Arduino Mega ADK Automated Plant Watering and Environmental Monitoring System

This circuit features an Arduino Mega ADK as the central microcontroller, interfacing with a variety of sensors and actuators. It includes a BH1750 light sensor and a DHT11 temperature and humidity sensor for environmental monitoring, both interfacing via I2C. The system controls a stepper motor via an A4988 driver, two water pumps through a 3-channel relay, and a fan using an IRF520 PWM module, with several push switches to trigger inputs. An OLED display provides a user interface, and soil moisture levels are monitored with two soil sensors. A non-contact water level sensor is also included for liquid level detection.

Open Project in Cirkit Designer

Arduino UNO Light Sensor with BH1750 and Relay Control

This circuit uses an Arduino UNO to interface with a BH1750 light sensor via I2C communication. The Arduino reads light intensity data from the BH1750 sensor, which is powered by the Arduino's 3.3V and GND pins.

Open Project in Cirkit Designer

Common Applications

• Automatic brightness control for LCD and OLED displays
• Energy-efficient lighting systems
• Smart home devices
• Weather monitoring stations
• Industrial automation systems

Technical Specifications

The following table outlines the key technical details of the BH1750:

Pin Configuration

The BH1750 has 8 pins, as described in the table below:

Usage Instructions

Connecting the BH1750 to a Microcontroller

To use the BH1750, connect it to a microcontroller (e.g., Arduino UNO) as follows:

1. Connect the VCC pin to the 3.3V power supply of the microcontroller.
2. Connect the GND pin to the ground of the microcontroller.
3. Connect the SCL pin to the I2C clock pin (A5 on Arduino UNO).
4. Connect the SDA pin to the I2C data pin (A4 on Arduino UNO).
5. Use a pull-up resistor (typically 4.7kΩ) on both the SCL and SDA lines for proper I2C communication.

Example Arduino Code

Below is an example Arduino sketch to read light intensity from the BH1750:

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

// Create an instance of the BH1750 sensor
BH1750 lightMeter;

void setup() {
  Serial.begin(9600); // Initialize serial communication
  Wire.begin();       // Initialize I2C communication

  // Initialize the BH1750 sensor
  if (lightMeter.begin()) {
    Serial.println("BH1750 initialized successfully.");
  } else {
    Serial.println("Error initializing BH1750. Check connections.");
    while (1); // Halt execution if initialization fails
  }
}

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

  // Print the light intensity to the serial monitor
  Serial.print("Light Intensity: ");
  Serial.print(lux);
  Serial.println(" lux");

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

Important Considerations

• Ensure the I2C pull-up resistors are properly connected to avoid communication issues.
• The BH1750 operates at 3.3V. If using a 5V microcontroller, use a level shifter for the I2C lines.
• Avoid exposing the sensor to direct sunlight for extended periods, as it may affect accuracy.

Troubleshooting and FAQs

Common Issues

1. No response from the sensor:

   • Verify the wiring and ensure the I2C lines (SCL and SDA) are correctly connected.
   • Check the I2C address (default is 0x23, but it can be changed to 0x5C using the ADDR pin).

2. Incorrect or fluctuating readings:

   • Ensure the sensor is not exposed to sudden changes in light intensity.
   • Verify that the power supply voltage is within the specified range (2.4V to 3.6V).

3. Sensor not initializing:

   • Confirm that the I2C pull-up resistors are in place.
   • Check for any loose connections or damaged wires.

FAQs

Q: Can the BH1750 measure light intensity in complete darkness?
A: No, the BH1750 cannot measure light intensity in complete darkness. Its minimum measurable value is approximately 1 lux.

Q: How do I change the I2C address of the BH1750?
A: The I2C address can be changed by setting the ADDR pin:

• Connect ADDR to GND for address 0x23.
• Connect ADDR to VCC for address 0x5C.

Q: Can the BH1750 be used outdoors?
A: While the BH1750 can operate in a wide temperature range, it is not waterproof. Use a protective enclosure for outdoor applications.

Q: What is the difference between high and low resolution modes?
A: High resolution mode provides more accurate readings but takes longer to measure, while low resolution mode is faster but less precise.