How to Use Adafruit BH1750: Examples, Pinouts, and Specs

The Adafruit BH1750 (Part ID: 4681) is a digital light sensor designed to measure ambient light levels in lux. It uses the I2C communication protocol, making it easy to integrate into microcontroller-based projects. The BH1750 is highly sensitive and provides precise light measurements, making it ideal for applications such as automatic lighting control, environmental monitoring, and photography.

• Automatic brightness adjustment for displays
• Smart home lighting systems
• Environmental monitoring and data logging
• Photography light metering
• Agricultural light intensity monitoring

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

The BH1750 sensor module has the following pinout:

To use the Adafruit BH1750 with an Arduino UNO, follow these steps:

1. Wiring:

   • Connect the VIN pin of the BH1750 to the 5V pin on the Arduino.
   • Connect the GND pin of the BH1750 to the GND pin on the Arduino.
   • Connect the SCL pin of the BH1750 to the A5 pin on the Arduino (I2C clock line).
   • Connect the SDA pin of the BH1750 to the A4 pin on the Arduino (I2C data line).
   • Optionally, connect the ADDR pin to GND (default I2C address: 0x23) or VCC (alternate I2C address: 0x5C).

2. Install Required Library:

   • Open the Arduino IDE.
   • Go to Sketch > Include Library > Manage Libraries.
   • Search for "Adafruit BH1750" and install the library.

3. Example Code: Use the following example code to read light levels from the BH1750:

   #include <Wire.h>
   #include <Adafruit_Sensor.h>
   #include <Adafruit_BH1750.h>
   
   // Create an instance of the BH1750 sensor
   Adafruit_BH1750 lightMeter;
   
   void setup() {
     Serial.begin(9600); // Initialize serial communication
     while (!Serial) {
       delay(10); // Wait for the serial port to connect
     }
   
     // Initialize the BH1750 sensor
     if (!lightMeter.begin()) {
       Serial.println("Error initializing BH1750 sensor!");
       while (1) {
         delay(10); // Halt execution if initialization fails
       }
     }
     Serial.println("BH1750 sensor initialized.");
   }
   
   void loop() {
     // Read light level in lux
     float lux = lightMeter.readLightLevel();
     if (lux < 0) {
       Serial.println("Error reading light level!");
     } else {
       Serial.print("Light Level: ");
       Serial.print(lux);
       Serial.println(" lux");
     }
     delay(1000); // Wait 1 second before the next reading
   }
   

• I2C Address Selection: Ensure the ADDR pin is correctly connected to select the desired I2C address (0x23 or 0x5C).
• Power Supply: The BH1750 operates on 3.0V to 5.0V. Ensure your power source matches this range.
• Pull-Up Resistors: The I2C lines (SCL and SDA) may require pull-up resistors (typically 4.7kΩ) if not already included on the module.

1. Sensor Not Detected:

   • Ensure the wiring is correct and matches the pin configuration.
   • Verify that the I2C address matches the one used in the code (default: 0x23).

2. Incorrect Light Readings:

   • Check for obstructions or reflections near the sensor.
   • Ensure the sensor is not exposed to extreme temperatures or humidity.

3. Code Compilation Errors:

   • Confirm that the Adafruit BH1750 library is installed in the Arduino IDE.
   • Ensure the correct board and port are selected in the Arduino IDE.

1. Can the BH1750 measure light levels in direct sunlight?

   • Yes, the BH1750 can measure up to 65,535 lux, which is sufficient for most outdoor applications.

2. What is the resolution of the BH1750?

   • The BH1750 has a resolution of 1 lux, making it suitable for precise light measurements.

3. Can I use the BH1750 with a 3.3V microcontroller?

   • Yes, the BH1750 is compatible with both 3.3V and 5V systems.

4. How do I change the I2C address?

   • Connect the ADDR pin to GND for the default address (0x23) or to VCC for the alternate address (0x5C).

By following this documentation, you can effectively integrate the Adafruit BH1750 into your projects for accurate and reliable light measurement.