GPIO I hear you say with a  glazed look in your eyes ?? Yes GPIO is the business end of the Raspberry Pi – in short we can plug in  sensors, switches , lights buzzers or control a Robot with it. GPIO is short for General Purpose Input / Output and we can use the 26 pins individually or with connectors such as GPIO ribbons and ‘cobblers’. Lets have a quick look at the mapping of the GPIO Pins. Let me first point out the difference between the 2 most common models though; Model B revision 1(256Mb) and  Model B revision 2 (512Mb). This is important in regards to mapping the ports using the Broadcom Model (BCM) commonly used in Python coding. As you can see the BCM labels differs from the Physical numbering of the pins (yes I know it’s confusing). The earlier model can be identified by the 6 extra pins near the Audio socket (blue), this is known as the i2c socket – missing on revision 2.


Model B Rev2                                        GPIO MAP                              Model B Rev1

The Key Pins on the GPIO socket are Ground (negative) in black, +3.3V and 5V in yellow / red giving power  out to a breadboard or breakout board of your choice, these are fixed and not programmable. I will be covering Revision 2 boards for most of my tutorials unless otherwise stated. GPIO Pins 17,18,22,23,25, 27 are the most useful pins for activating and controlling outputs – a word of warning : NEVER power an electric motor directly from the GPIO pins – you WILL damage your Raspberry Pi. A breakout board will require an additional power source for the electric motor – but will easily enable you to control the motors speed and direction; yes we’re heading for robotics here. Another Key pair of Pins are GPIO 14(TxD) and 15(RxD) which will enable us to communicate with an Arduino board or module -now we’re talking analogue inputs/outputs and Pulse Width Modulation (PWM). You what modulation ?? Well we can control sequences , brightness levels and artificial audio effects (SFX) – whoooaaa !!

Big Update: As you all probably are aware RaspberryPi has launched Model B+ and added another 14pins to the GPIO –  40 in total. The Good News is that the original 26 pins from Model B are in the same position making most breakout boards backward compatible. Please have a look at the excellent interactive GPIO Map from Gadgetoid here.

Model B+ GPIO Layout


A selection of Breakout boards to be reviewed, exciting times . . . 


Pages under construction, please be patient !

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