TSL2561

Connect sensor to I2C:

Configure i2c on the Raspberry Pi

sudo apt-get install i2c-tools python-smbus

Add the following lines to /boot/config.txt:

#i2c
dtparam=i2c_arm=on,i2c1=on

Edit the file /etc/modules and add the following line:

i2c-dev

Finally reboot:

sudo reboot

After the reboot you should be able to find the i2c device using the command below:

sudo i2cdetect -y 1