---
layout: page
title: "BH1750 Light sensor"
description: "Instructions how to integrate a BH1750 light sensor into Home Assistant."
date: 2017-06-10 00:00
sidebar: true
comments: false
sharing: true
footer: true
logo: raspberry-pi.png
ha_category: Sensor
ha_release: 0.48
ha_iot_class: "Local Push"
---


The `bh1750` sensor platform allows you to read the ambient light level in Lux from a [BH1750FVI sensor](http://cpre.kmutnb.ac.th/esl/learning/bh1750-light-sensor/bh1750fvi-e_datasheet.pdf) connected via [I2c](https://en.wikipedia.org/wiki/I²C) bus (SDA, SCL pins). It allows you to use all the resolution modes of the sensor described in its datasheet.

Tested devices:

- [Raspberry Pi](https://www.raspberrypi.org/)


To use your BH1750 sensor in your installation, add the following to your `configuration.yaml` file:

```yaml
# Example configuration.yaml entry
sensor:
  - platform: bh1750
```

Configuration variables:

- **name** (*Optional*): The name of the sensor
- **i2c_address** (*Optional*): I2c address of the sensor. It is 0x23 or 0x5C.
- **i2c_bus** (*Optional*): I2c bus where the sensor is. Defaults to 1, for Raspberry Pi 2 and 3.
- **operation_mode** (*Optional*): Working mode for the sensor. Defaults to `continuous_high_res_mode_1` for continuous measurement and 1 lx resolution.
- **measurement_delay_ms** (*Optional*): Delay time in ms for waiting the sensor to get the measure. Defaults to 120 ms.
- **multiplier** (*Optional*): Correction coefficient to multiply the measured light level. Value between 0.1 and 10. Default is 1.


## {% linkable_title Full Examples %}

If you want to specify the resolution mode of the digital sensor or need to change the default I2c address (which is 0x23), add more details to the `configuration.yaml` file.

The sensor can work with resolutions of 0.5 lx (high res mode 1), 1 lx (high res mode 2) or 4 lx (low res mode), and make measurements continuously or one time each call. To set any of these operation modes, select one of these combinations: `continuous_low_res_mode`, `continuous_high_res_mode_2`, `continuous_high_res_mode_1`, `one_time_high_res_mode_1`, `one_time_high_res_mode_2`, `one_time_low_res_mode`.

```yaml
# Example of customized configuration.yaml entry
sensor:
  - platform: bh1750
    name: Ambient light
    i2c_address: 0x5C
    operation_mode: one_time_high_res_mode_1
    measurement_delay_ms: 200
    scan_interval: 25
```

## {% linkable_title Directions for installing smbus support on Raspberry Pi %}

Enable I2c interface with the Raspberry Pi configuration utility:

```bash
# pi user environment: Enable i2c interface
$ sudo raspi-config
```

Select `Interfacing options->I2C` choose `<Yes>` and hit `Enter`, then go to `Finish` and you'll be prompted to reboot.

Install dependencies for use the `smbus-cffi` module and enable your _homeassistant_ user to join the _i2c_ group:

```bash
# pi user environment: Install i2c dependencies and utilities
$ sudo apt-get install build-essential libi2c-dev i2c-tools python-dev libffi-dev

# pi user environment: Add homeassistant user to the i2c group
$ sudo addgroup homeassistant i2c

# pi user environment: Reboot Raspberry Pi to apply changes
$ sudo reboot
```

### {% linkable_title Check the i2c address of the sensor %}

After installing `i2c-tools`, a new utility is available to scan the addresses of the connected sensors:

```bash
$ /usr/sbin/i2cdetect -y 1
```

It will output a table like this:

```text
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- 23 -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: 40 -- -- -- -- -- UU -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- 77
```

So you can see the sensor address what you are looking for is **0x23** (there are more i2c sensors in that Raspberry Pi).
