In this blog we look at the BH1750 light intensity sensor breakout board with a 16 bit AD converter built-in which can directly output a digital signal, there is no need for complicated calculations. This is a more acurate and easier to use version of the simple LDR which only outputs a voltage that needs to be calculated in order to obtain meaningful data.
BH1750
With the BH1750 Light Sensor intensity can be directly measured by the luxmeter, without needing to make calculations. The data which is output by this sensor is directly output in Lux (Lx). When objects which are lighted in homogeneous get the 1 lx luminous flux in one square meter ,their light intensity is 1lx. Sometimes to take good advantage of the illuminant, you can add a reflector to the illuminant. So that there will be more luminous flux in some directions and it can increase the ilumination of the target surface.
Typical Illuminance:
- Night: 0.001–0.02
- Moonlightnight: 0.02–0.3
- Cloudy indoor: 5–50
- Cloudy outdoor: 50–500
- Sunny indoor: 100–1000
- Under the sunlight in summer afternoon: about 10*6 power
- Reading books for intensity of illumination: 50–60
- Home video standard intensity of illumination: 1400
Properties:
- I2C bus Interface
- Spectral responsibility is approximately human eye response
- Illuminance to Digital Converter
- Wide range and High resolution. ( 1 – 65535 lx )
- Low Current by power down function
- 50Hz / 60Hz Light noise reject-function
- Light source dependency is little. ( ex. Incandescent Lamp. Fluorescent Lamp. Halogen Lamp. White LED. Sun Light)
- It is possible to select 2 type of I2C slave-address
- Adjustable measurement result for influence of optical window
- Small measurement variation (+/- 20%)
- The influence of infrared is very small
- Operating Voltage: 3.3V-5V
- Dimensions: 0.85*0.63*0.13″(21*16*3.3mm)
For more information on the sensor, please refer to the BH1750 data sheet.
BH1750 board Pinouts
Most of the sensor’s Breakout board has 5 pins, There are also other variants such as the BH1750FVI, this one has a different pinout!
| Pin | Name | Function |
| 1 | ADDR | Select I2C slave-address |
| 2 | SDA | Serial Data Pin for I2C Interface / MOSI Pin for SPI Communication |
| 3 | SCL | Serial Clock Pin for I2C Interface / SCK Pin for SPI Communication |
| 4 | GND | GND Pin |
| 5 | VCC (3.3v – 5v) | Power supply pin requires 3.3V to 5.0V for operation |
Changing the default I2C address
ADDR/AD0 Jumper – I2C Address pin. Pulling this pin high or bridging the solder jumper on the back will change the I2C address from 0x23 to 0x5C
Breakout scheme
The basic concept of a breakout board is that is takes a single electrical component and makes it easy to use. Usually the electrical component is an integrated circuit (IC). Integrated circuits, as you may know, have pins on them. The pins on an IC can do a multitude of things, but you usually have pins for supply power, pins for providing a ground, pins for receiving an input and pins for sending an output. A breakout board “breaks out” these pins onto a printed circuit board that has its own pins that are spaced perfectly for a solderless breadboard, giving you easy access to use the integrated circuit.
Interfacing BH1750 with Arduino using I2C Interface
The BH1750 light intensity sensor has a I2C Interface. We will have a look how to use the I2C Pins of BH1750 to interface it with Arduino Nano Board. The connection between BH1750 & Arduino Nano is fairly simple. Connect the VCC pin of the BH1750 to Arduino 3.3V Pin and GND to GND. Similarly, connect the I2C Pins of BH1750, SDA and SCL Pins to Arduino A4 and A5 Pins respectively.
BH1750 Library’s
Using the BH1750 with Arduino is a simple matter of wiring up the sensor to your Arduino-compatible microcontroller, installing the hp_BH1750 library written by Stefan Armborst, and running one of many very well written examples.
Download: hp_BH1750
Or download the hp_BH1750 library trough the Arduino library manager.
Source Code/program
Testing & Results
You can use the above circuits, the I2C circuit. Then upload one of the codes according to the circuit diagram. Open the serial monitor after uploading the code to the Arduino Nano board.
REFERENCE
ROHM Co., Ltd.,Ambient Light Sensor IC Series (2021), The digital SHT3x humidity sensor series takes sensor technology to a new level. , http://www.farnell.com/datasheets/1813320.pdf Stefan Armborst,hp_BH1750 (2021),a high-performance non-blocking library, https://github.com/adafruit/Adafruit_SHT31