photo resistor.

[umbra070]

Hello! I buy raspberry and now i have some questions:
How can i use photo resistor? he have boolean data or int?

[Tarcas]

You need an analog-to-digital converter. A photoresistor produces an analog output, which the Pi cannot interpret. They're quite inexpensive on Ebay.

[GTR2Fan]

You can charge a small capacitor through the photoresistor from a toggled GPIO output pin and cyclically time how long it takes for the centre-point voltage to fall below the voltage threshold of another GPIO pin set as input.

It's not something I've tried myself, but it's an often mentioned method for measuring electrical resistance on a Pi.

[boyoh]

photo resistor_schem.jpg (37.6 KiB) Viewed 1840 times

Build this circuit up on a bread board, This will help you
To understand how a Photo Resistor works

[Richard-TX]

For $2 delivered, you can have a photoresistor, temp sensor and more all connected to a ADC.



http://www.ebay.com/itm/1PC-New-AD-DA-C ... 2c71d20f9d