The Raspberry Pi is a small card size LINUX based computer board designed and intended for students, hobbyists, electronics and computer enthusiasts. It was first released in February 2012 and from then on undergone several developments. The RPi has the capability of most personal computers available in the market except that it has the primary advantage of being configurable for various purposes and applications. It has become very popular for Robotics and Automation experimenters and tinkerers because of its size and low power consumption. It can be customized according to the preference of the user and be operated using an ordinary and commonly available batteries. Power source for RPi is not a problem because it can be powered by regular smartphone charger or using Lithium-Ion or Ni-Cad batteries connected through 5 Volts DC regulator capable of delivering current of atleast 1.5 Amperes.  However, compare to Arduino microcontroller board and the like, Raspberry Pi does not support real time processing. Nevertheless, this limitation did not hinder to the success of RPi's popularity.

There are now seven Raspberry Pi models available in the market and they are as follows:

1. Model A

2. Model A+

3. Model B

4. Model B+

5. Model Raspberry Pi 2

6. Raspberry Pi Zero

7. Raspberry Pi 3 - with built-in Wi-Fi and Bluetooth

8. Raspberry Pi 3 - Model B

9. Raspberry Pi Zero W

THE OPERATING SYSTEM

There are many software developers and companies that supports the Raspberry Pi. Because of this, users can choose among several Operating Systems as listed here: 

1.  RASPBIAN (Debian)

2.  RISC OS

3. SNAPPY UBUNTU CORE

4. UBUNTU MATE

4. OPENELEC

5. RASPBMC

6. PIDORA

7. WINDOWS 10 IOT CORE

8. OSMC

9. PINET

10. LIBREELEC

PROGRAMMING LANGUAGE

Several programming languages exist for the RPi's and mostly included in the Operating System that can be downloaded. Currently, there are two types of GPIO P1 terminal configuration that can be programmed or accessed. The older version has 26 pins and the latest version has 40 pins which provided additional GPIOs.

Below is just some of the programming languages that can be use to control the GPIO terminals.

1. Phyton

2. BBC BASIC

3. Return to BASIC

4.  Scratch

5. HTML5

6. JQuery

7. Java

8. JavaScript

9. C Language

10. Perl

11. Erlang