Pimatic support for the bh1750 light intensity sensor
I2C drivers need to be loaded in order to create the connection between the physical sensor and the rPI. You can load them from the terminal (or from the /etc/modules script).
sudo modprobe i2c_dev sudo modprobe i2c_bcm2708
You might also need to uncomment the following line in /boot/config.txt
Add the plugin to the plugin section:
Then add a sensor for your device to the devices section: