In a previous post, I mentioned that you need to use a resistor when connecting an LED to the GPIO, but how do you know what value resistor to use?

The reason we need a resistor is because the LED will only stand so much current before it blows.

There are 2 output voltages from the GPIO pins, 3.3v from pins 1 and 17, and 5v from pins 2 and 4.

Lets say you have a 5mm blue LED from maplin (Something like this) there are 2 important bits of information you need to calculate the resistor to use with it. The Forward Voltage and the Forward Current.

It's been a while since my last post, I've been very busy with lots other things (getting married, having a baby, changing jobs) so haven't had much chance to play with my Raspberry Pi or post on here.

A lot has happened in the Raspberry Pi world in that time too, there have been a number of different versions of the Raspberry Pi hardware as well as a a lot more providers of add on boards and kits built specifically for the Raspberry Pi. Here I'll take a look at the different hardware available and some other things that look interesting.

First we'll create a circuit which we can control with the Raspberry Pi.

We're going to have a simple circuit with one LED which we'll use Python to control.

When using the GPIO I would recommend getting a breadboard and an Adafruit Pi Cobbler Breakout Kit. This will allow you to easily connect the Raspberry Pi to a breadboard so you can quickly and easily build circuits.

So you want to start using the GPIO and connecting your Raspberry Pi to a breadboard to turn on some LEDs or power some motors etc. But what exactly is a breadboard and how does it work?