How to Use BH1750: Examples, Pinouts, and Specs

The BH1750 is a digital light sensor designed to measure ambient light intensity in lux, providing precise and reliable readings. It communicates via the I2C protocol, making it easy to integrate with microcontrollers and development boards. The sensor is highly sensitive and can detect a wide range of light levels, from very dim to bright sunlight.

• Automatic brightness control for LCD and OLED displays
• Energy-efficient lighting systems
• Smart home automation (e.g., light-based triggers)
• Weather monitoring stations
• Photography and camera exposure control

The BH1750 is a compact and efficient sensor with the following key specifications:

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

1. Power the Sensor: Connect the VCC pin to a 3.3V power source and the GND pin to ground.
2. I2C Communication: Connect the SDA and SCL pins to the corresponding I2C pins on your microcontroller. Use pull-up resistors (typically 4.7kΩ) on the SDA and SCL lines if not already present.
3. Address Selection: Use the ADDR pin to select the I2C address:
   • Connect ADDR to GND for address 0x23.
   • Connect ADDR to VCC for address 0x5C.
4. Initialize the Sensor: Configure the I2C interface on your microcontroller and initialize the BH1750 in the desired measurement mode.

• Avoid Direct Light: Place the sensor in a location where it can measure ambient light without being exposed to direct light sources.
• Power Supply Stability: Ensure a stable power supply to avoid measurement inaccuracies.
• Measurement Modes: The BH1750 supports multiple modes, such as continuous and one-time measurement. Choose the mode that best suits your application.
• I2C Pull-Up Resistors: Verify that pull-up resistors are present on the I2C lines to ensure proper communication.

Below is an example of how to use the BH1750 with an Arduino UNO:

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

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

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

  // Initialize the BH1750 sensor in continuous high-resolution mode
  if (lightMeter.begin(BH1750::CONTINUOUS_HIGH_RES_MODE)) {
    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
}

1. No Response from the Sensor

   • Cause: Incorrect I2C address or wiring.
   • Solution: Verify the ADDR pin connection and ensure the correct I2C address is used in the code. Check all wiring connections.

2. Inaccurate Readings

   • Cause: Sensor exposed to direct light or unstable power supply.
   • Solution: Shield the sensor from direct light and ensure a stable power source.

3. I2C Communication Errors

   • Cause: Missing or incorrect pull-up resistors on SDA and SCL lines.
   • Solution: Add 4.7kΩ pull-up resistors to the SDA and SCL lines if not already present.

4. Sensor Not Detected

   • Cause: Incorrect initialization or damaged sensor.
   • Solution: Double-check the initialization code and replace the sensor if necessary.

Q: Can the BH1750 measure light intensity in complete darkness?
A: The BH1750 can measure very low light levels, but it cannot detect absolute darkness (0 lux).

Q: What is the difference between continuous and one-time measurement modes?
A: In continuous mode, the sensor continuously measures light intensity and updates the data register. In one-time mode, the sensor performs a single measurement and enters a low-power state.

Q: Can the BH1750 operate at 5V?
A: No, the BH1750 operates at a voltage range of 2.4V to 3.6V. Use a level shifter if interfacing with a 5V system.