This post details my first and simplest attempt at driving some LEDs with a Pi. 3 LEDs, 3 resistors and some wires.
The circuit diagram, breadboard version and veroboard version are shown. Python source code for the traffic light sequence is shown.
Next will be versions of traffic lights using transistors and then an I2C bus expander.
There’s a couple of good sources of explanations for the pin-outs of the Raspberry Pi’s GPIO connector.
My favorite being the one on LWK’s Arduino Projects blog. Don’t let the title fool you, the author has seen the light and is tinkering with Pi’s too.
Recently the Raspberry Pi foundation announced Rev 2.0 of the board. I only have Rev 1.0 boards, so don’t need to worry about the pin-out changes just yet. Either way, it is simple enough to make your circuits compatible with both.