Table of Contents
Overview:
In this tutorial, let’s learn how to connect BH1750 light intensity sensor with Arduino and display the light intensity values on 16X2 LCD display in Lux Units. So in this article you are going to learn the Overview of BH1750 light sensor, How BH1750 sensor works? and interfacing it with Arduino Microcontroller.
BH1750 Light sensor Overview:
BH1750 is a digital ambient light sensor which measures the light intensity incident on the sensor and converts it into a 16 bit digital number. It doesn’t required any type of converting modules as the sensor itself has an ADC which converts and outputs a digital signal.
BH1750 uses I2C communication protocol to transmit the data which makes it compatible with almost all microcontroller boards. BH1750 directly outputs the measured light in Lux units which is the unit of light intensity.
Working of BH1750 Light intensity sensor:
BH1750 Sensor board contains BH1750FVI IC. When an Ambient light is incident on the sensor the photo diode with a latency nearly equals to human eye absorbs the light and produces an analog voltage signal which is further connected to ADC unit to convert it from analog to digital 16 bit data.
In the next step with the help of two registers data register and time register the light intensity is calculated and transmit the data signal through I2C bus.
This sensor is mainly used in LCD displays, TVs, Monitors and mainly in Mobile displays to automatically adjust the screen brightness according to the outdoor light conditions. This sensor can also used to Turn on/Off the lights.
You might be thinking of LDR(Light dependent Resistor) which works as same but this BH1750 sensor has more advantages like higher accuracy and stability over LDR.
BH1750 Pinout diagram:
From the above pinout diagram as you can see there are 5 pins. 2 Pins for power supply VCC and GND. Another 2 pins for I2C communication SCL and SDA. And the last one is I2C Address pin which we are not going to use in this tutorial.
Related project: UV index meter interfacing Arduino
Technical specifications of BH1750:
- Operating voltage: 3v to 5v
- Measures Lux range with a high resolution from 1 to 65535lx.
- Illuminance to Digital Converter
- The influence of infrared is very small
- Small measurement variation (+/- 20%)
- Feature to select 2 types of I2C addresses.
- Low power consumption
Interfacing BH1750 with Arduino Microcontroller and LCD Display
Bill of Materials:
| Product Name | Quantity |  |  |
|---|---|---|---|
| BH1750 Ambient light intensity sensor | 1 | https://amzn.to/33C6aRT | https://amzn.to/3J0WRKw |
| Arduino Uno Microcontroller | 1 | https://amzn.to/3H4cKxZ | https://amzn.to/3638aTS |
| 16X2 LCD display module with I2C adapter | 1 | https://amzn.to/3I3Uaax | https://amzn.to/363ki7F |
| Few Connecting Wires | https://amzn.to/3H2BV4e | https://amzn.to/3J0WVu2 | |
| 5V power supply (Micro USB or External). | 1 | https://amzn.to/3s1a8g3 | https://amzn.to/364yInH |
Circuit Diagram:
Connect all the required components according to the below circuit diagram
As you can see from the above pinout diagram BH1750 power pins VCC and GND are connected to 3.3v and GND pins of Arduino respectively. The I2C pins of BH1750 SDA and SCL are connected to A4 and A5 pins of Arduino respectively.
The power pins VCC and GND of 16X2 LCD display with I2C adapter is connected to 5V and GND pins of Arduino respectively and I2C communication pins SDA and SCL are connected to the same A4 and A5 of Arduino respectively.
That’s it for connection now its time to upload the code to Arduino
Program Code:
Now connect the Arduino to the PC where Arduino IDE is installed to upload the below code. This source code required few libraries which are listed below, you can install them directly through Arduino IDE library manager or you can Download them from the below links and extract them into libraries folder in Documents.
Copy the below code and paste it into Arduino IDE workspace and hit upload button.
/***** Full Tutorial of BH1750 with Arduino on https://www.circuitschools.com *****/
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <BH1750.h>
BH1750 lightMeter(0x23);
LiquidCrystal_I2C lcd (0x27, 16,2);
void setup(){
Serial.begin(9600);
// Initialize the LCD connected
lcd. init ();
// Initialize the I2C bus (BH1750 library doesn't do this automatically)
Wire.begin();
// Turn on the backlight on LCD.
lcd. backlight ();
lcd. print ( "Light Intensity:" );
/*
Full mode list:
BH1750_CONTINUOUS_LOW_RES_MODE
BH1750_CONTINUOUS_HIGH_RES_MODE (default)
BH1750_CONTINUOUS_HIGH_RES_MODE_2
BH1750_ONE_TIME_LOW_RES_MODE
BH1750_ONE_TIME_HIGH_RES_MODE
BH1750_ONE_TIME_HIGH_RES_MODE_2
Each mode, has three different precisions:
- Low Resolution Mode - (4 lx precision, 16ms measurement time)
- High Resolution Mode - (1 lx precision, 120ms measurement time)
- High Resolution Mode 2 - (0.5 lx precision, 120ms measurement time)
*/
// begin returns a boolean that can be used to detect setup problems.
if (lightMeter.begin(BH1750::CONTINUOUS_HIGH_RES_MODE)) {
Serial.println(F("BH1750 Advanced begin"));
}
else {
Serial.println(F("Error initialising BH1750"));
}
}
void loop() {
float lux = lightMeter.readLightLevel();
Serial.print("Light: ");
Serial.print(lux);
Serial.println(" lx");
lcd.setCursor (0, 1);
lcd.print(lux);
lcd.print(" Lux");
delay(1000);
}
After uploading the code you can see the light intensity lux values are displayed on the serial monitor and LCD display module. You can check with any light sources like torch light, flashlight or even sun.
Output:
As you can see from the output image that when a light falls on the sensor it shows the intensity of the light on the LCD display connected. Through this values you can create projects like automatic streetlights, Automatic sensor car headlamps and more.
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