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https://github.com/claws/BH1750

An Arduino library for the digital light sensor breakout boards containing the BH1750FVI IC
https://github.com/claws/BH1750

arduino arduino-library light lux sensor

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An Arduino library for the digital light sensor breakout boards containing the BH1750FVI IC

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README 

        
# BH1750



[![Build Status](https://github.com/claws/BH1750/workflows/checks/badge.svg?branch=master)](https://github.com/claws/BH1750/actions)



This package contains an Arduino library for digital light sensor breakout boards containing the

BH1750FVI IC.



The BH1750 board uses I2C for communication which requires two pins to

communicate with the device. Configuring the I2C bus must be done in user code

(not library code). This approach has been adopted so it can be done once and

will better support the various options for different platforms.



A common module containing the BH1750 component is the GY-30 shown below.



![GY-30 Module image](resources/gy30-module.jpg)



## Overview



The BH1750 has six different measurement modes which are divided in two groups;

continuous and one-time measurements. In continuous mode the sensor

continuously measures lightness value. In one-time mode, the sensor makes only

one measurement and then goes into Power Down mode.



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)



By default, this library uses Continuous High Resolution Mode, but you can

change this to a different mode by passing the mode argument to

BH1750.begin().



When the One-Time mode is used your sensor will go into Power Down mode when

it completes the measurement and you've read it. When the sensor is powered up

again it returns to the default mode which means it needs to be reconfigured

back into One-Time mode. This library has been implemented to automatically

reconfigure the sensor when you next attempt a measurement so you should not

have to worry about such low level details.



Usually you will get an integer value which represent the lux equivalent.

  - Low Resolution Mode - (generic range: 0.0 up to 54612.5 lux)

  - High Resolution Mode - (generic range: 0.0 up to 54612.5 lux)

  - High Resolution Mode 2 - (generic range: 0.0 up to 27306.25 lux)



The sensor itself returns a 16 bit unsigned integer. Therefore the maximum value is limited in general.

The standard conversion between the so called 'counts' to lux is 1/1.2, that means you get a smaller value.

As we use float, if an error occurs you will get a negative value.

  - -1 no valid data was transmitted from the sensor

  - -2 device is not configured

Otherwise the measured counts are converted to lux and returned. If no advanced parameters are changed the maximum lux value is 54612.5 lx.



As the sensor counts impact of light in a specific time frame you could change this time frame.

This is needed if you use an overlay window or compensate for environmental influence like darkness.

This time frame is defined by a register which is called MTreg. Therefore you could choose a value between 32 and 254.

The default value is 69; keep in mind that the measurement time is changed accordingly.



The datasheet for the BH1750 chip can be obtained

[here](https://www.mouser.de/datasheet/2/348/Rohm_11162017_ROHMS34826-1-1279292.pdf)[2011.11 Rev.D]



## Installation [![arduino-library-badge](https://www.ardu-badge.com/badge/BH1750.svg?)](https://www.ardu-badge.com/BH1750)



- **(For Arduino >= 1.5.x)** Install this package by searching for it in the

  Arduino Library Manager and then clicking ``install``. Alternatively, this

  library can be installed manually by clicking "Clone or download" -> "Download ZIP"

  button. Then open Arduino IDE, click `Sketch -> Include library -> Add .ZIP library`

  and select the downloaded archive.



- **(For Arduino < 1.5.x)** Download this package as an archive by clicking

  "Clone or download" -> "Download ZIP" button. Then extract the archive to

  ``/My Documents/Arduino/libraries/`` folder and rename

  it to `BH1750`. Restart IDE.



The following YouTube [video](https://youtu.be/ACTMQvPVMLs) (specifically from

7:20 onwards) provides a good overview of manually installing this library and

loading an example using the Arduino IDE.



[![BH1750 Video Tutorial](https://img.youtube.com/vi/ACTMQvPVMLs/0.jpg)](https://youtu.be/ACTMQvPVMLs?t=437)



Information about the library installation process - https://www.arduino.cc/en/Guide/Libraries



## Example



An example using the BH1750 library in conjunction with the GY-30 board

(which contains the BH1750 component) is presented below. The example

code uses the BH1750 library in the default continuous high precision

mode when making light measurements.



### Wiring



Connections:



  - VCC -> 3V3 or 5V

  - GND -> GND

  - SCL -> SCL (A5 on Arduino Nano, Uno, Leonardo, etc or 21 on Mega and Due, on esp8266 free selectable)

  - SDA -> SDA (A4 on Arduino Nano, Uno, Leonardo, etc or 20 on Mega and Due, on esp8266 free selectable)

  - ADD -> NC/GND or VCC (see below)



The ADD pin is used to set the sensor I2C address. By default (if ADD voltage

less than 0.7 * VCC) the sensor address will be 0x23. If it has voltage

greater or equal to 0.7VCC voltage (e.g. you've connected it to VCC) the

sensor address will be 0x5C.



Wiring up the GY-30 sensor board to an Arduino is shown in the diagram below.



![Example wiring diagram image](resources/wiring-diagram-gy30-module.png)



*The image above was created using [Fritzing](http://fritzing.org/home/) and

the GY-30 module was obtained from [here](http://omnigatherum.ca/wp/?p=6)*.



### Code



Upload the BH1750 test code to your Arduino.



``` c++

#include 

#include 



BH1750 lightMeter;



void setup(){



  Serial.begin(9600);



  // Initialize the I2C bus (BH1750 library doesn't do this automatically)

  // On esp8266 devices you can select SCL and SDA pins using Wire.begin(D4, D3);

  Wire.begin();



  lightMeter.begin();

  Serial.println(F("BH1750 Test"));



}



void loop() {



  float lux = lightMeter.readLightLevel();

  Serial.print("Light: ");

  Serial.print(lux);

  Serial.println(" lx");

  delay(1000);



}

```



### Output



Moving the sensor to face more light results in the lux measurements increasing.

```

BH1750 Test

Light: 70.0 lx

Light: 70.0 lx

Light: 59.0 lx

Light: 328.0 lx

Light: 333.0 lx

Light: 335.0 lx

Light: 332.0 lx

```



### More Examples



The ``examples`` directory contains more advanced use cases such as using different modes, I2C addresses and multiple Wire instances.



## Developers



The following information is for developers of this library.

### Code Format



The code in this project is formatted using ``clang-format`` tool.



Good instructions for installing ``clang-format`` can be found

[here](https://learn.adafruit.com/the-well-automated-arduino-library/formatting-with-clang-format)



Once the ``clang-format`` tool has been install you can then run the

convenience script (``ci/code-format.bash``) to check or apply the code

formatting. The script should be run from the repo's top level directory.



```shell

$ ./ci/code-format.bash

```

This script is also run as part of the project's continuous integration

checks.



If you make changes to code files then the code format can be applied

by simply passing *apply* as an argument to the script.



```shell

$ ./ci/code-format.bash apply

```



### Code Linting



The code in this project is linted using ``arduino-lint``. The tool can be

installed using the instructions [here](https://arduino.github.io/arduino-lint/latest/installation/).



To run the linter over the project use the command below.



```shell

$ arduino-lint --library-manager update --compliance strict

```



The same command is run as part of the project's continuous integration

checks.



If errors or warnings are reported then fix them and re-run the script

until they are resolved.



### Build Locally



The code in this project can be built locally using the ``arduino-cli`` tool.

The tool can be installed using the instructions [here](https://github.com/arduino/arduino-cli#quickstart). Once you have the tool installed you can compile the

examples scripts using the convenience script (``ci/compile-examples.bash``).



```shell

$ ./ci/compile-examples.bash

```



This script performs the same actions as the project's continuous integration

compile checks.



### Release Process



- Update ``library.json`` and ``library.properties`` version strings.

- Create a new project release and use the new version number as tag. Click Publish.

- Now wait about an hour for it to appear in the Arduino library manager.