BH1750FVI Is a Digital Light sensor , which is an digital Ambient Light Sensor IC for I2C bus interface. This IC is the most suitable to obtain the ambient light data for adjusting LCD and Keypad backlight power of Mobile phone. It is possible to detect wide range at High resolution.( 1 – 65535 lx ).
1) Illuminance to Digital Converter
2) Wide range and High resolution. ( 1 – 65535 lx )
3) Low Current by power down function
4) 50Hz / 60Hz Light noise reject-function
5) I2C bus Interface ( f / s Mode Support )
6) No need any external parts
7) It is possible to select 2 type of I2C slave-address.
8) It is possible to detect min. 0.11 lx, max. 100000 lx by using this function.
Step 1: Definition of luminous ,Lumen
illuminance is a measure of how much luminous flux is spread over a given area. One can think of luminous flux (measured in lumens) as a measure of the total “amount” of visible light present, and the illuminance as a measure of the intensity of illumination on a surface
Lumen : The unit for the quantity of light flowing from a source in any one second (the luminous power, or luminous flux) is called the lumen.
In our sensor we will take a reading from it in Lux which is equal to one lumen per square metre:
Lux = 1 Lm/m2 .
Step 2: Datasheet …..inside
The DataSheet for BH1750 has a specification of :
Supply voltage : prefer to use 3.3 V to communicate with , Not 5V TTL Logic
I2C Protocol is used to communicate with Microcontroller , with clock SCL Frequency 400KHz .
Measurement mode: this sensor has 3 Measurement mode :
1) H-resolution with Sensitivity 0.5 lux
2) H-Resolution with Sensitivity 1 lux.
3) L-Resolution with Sensitivity 4 lux.
the datasheet recommended to use H-Resolution Mode due to kind of noise( including in 50Hz / 60Hz
noise ) is rejected. And H-Resolution Mode is 1 l x resolution so that it is suitable for darkness ( less than 10 lx )
the Instruction Set Architect table show all commend you will need to write a code .
For more detail: BH1750 Digital Light Sensor