Hi guys, continuing on our recent path of building really cool stuffs based on the Nokia 5110 LCD display, today we will be building a DIY Lux (or light) meter using the highly sensitive BH1750 light sensor.
Illuminance (measured in LUX) is the total luminous flux incident on a surface, per unit area. It is a measure of how much the incident light illuminates the surface, it is wavelength-weighted by the luminosity function to correlate with the level of human brightness perception.
Lux is a measurement of the overall intensity of light within an environment for any given area or distance from the source or lux is the amount of light in an environment perceived by the human eye. The Lux meter is thus, a device used to measure the light intensity within an environment and its exactly what we will be building during this tutorial.
Below is a picture of the device taking outdoor readings on a bright morning.
The BH1750 sensor is a digital Light Sensor capable of measuring light intensity with a great degree of accuracy and over a large range. It communicates with microcontrollers or processors to which it is connected via the I2C bus interface. This module is the most suitable to obtain the ambient light data and it is commonly used for adjusting LCD and Keypad backlight power of Mobile phones.
Some of the features of this sensor include;
- I2C bus Interface ( f / s Mode Support )
- 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
- It is possible to select 2 type of I2C slave-address.
- Adjustable measurement result for influence of optical window ( It is possible to detect min. 0.11 lx, max. 100000 lx by using this function. )
- Small measurement variation (+/- 20%)
The following components are needed to build this project;
Connect all components as shown in the Fritzing schematics below;