Giuseppe Parrello

 

Ambient Light Sensor Rohm BH1750


Introduction

This embedded sensor, measuring Ambient Light, is based on the Rohm BH1750 chipset and it is compatible with the I2C serial interface. For ease we are going to connect it to the FTDI FT232H device, of which there is a dedicated page on this site - refer to the above page for installation.

 

Connection via I2C

This sensor must be connected to the FTDI FT232H development board via I2C protocol. The connection connectors are listed below:

Image Board FT232H Sensor BH1750

FT232H - BH1750

AD0 SCL
AD1 + AD2 SDA
+5V / +3.3V VCC
GND GND

The default hexadecimal address of this sensor is "23", but it is possible to change it by connecting pin ADDR of sensor to pin +5V or to pin +3.3V of development board FTDI FT232H. In this way hexadecimal address becomes "5C".

To get the hexadecimal address of this sensor, go to the PyFTDI website and download the following Python script. Once downloaded, run it via the Python interpreter. The output of the above script is as follows:

admin@RT-AC86U:/# python3 i2cscan.py

   0 1 2 3 4 5 6 7 8 9 A B C D E F
0: . . . . . . . . . . . . . . . .
1: . . . . . . . . . . . . . . . .
2: . . . W . . . . . . . . . . . .
3: . . . . . . . . . . . . . . . .
4: . . . . . . . . . . . . . . . .
5: . . . . . . . . . . . . . . . .
6: . . . . . . . . . . . . . . . .
7: . . . . . . . . .

 

Python libraries

To manage this sensor, we can use one of the following Python libraries: