Blinking LEDs is a popular application in the field of embedded development. In Raspberry Pi LED Blueprints by Agus Kurniawan, we are going to design, build, and test LED-based projects using the Raspberry Pi. To Implement real LED-based projects for Raspberry Pi, we need to learn how to interface various LED modules, such as LEDs, 7-segment, 4-digit 7-segment, and dot matrix to Raspberry Pi. We will get hands-on experience by exploring real-time LEDs with this project-based book.

(For more resources related to this topic, see here.)

Why Raspberry Pi?

The Raspberry Pi was designed by the Raspberry Pi Foundation in the UK initially to help schoolkids learn basic computer science knowledge. The Raspberry Pi uses Linux as a basic programming language, and they attempt to come up with their own language that fits this technology better sometime in the future. Although Raspberry Pi is as small as the size of a credit card, it works like a normal computer at a relatively low price. A Raspberry Pi can easily control an LED, which is a simple actuator device that displays lighting. This book will provide you with the ability to control LEDs using Raspberry Pi.

What this article covers?

This article covers introduction of Raspberry Pi GPIO. In this, we will learn how to use different libraries to access Raspberry Pi GPIO. The step-by-step procedure to install it is also provided along with the Python command.

Introducing Raspberry Pi GPIO

General-purpose input/output (GPIO) is a generic pin on the Raspberry Pi, which can be used to interact with external devices, for instance, sensor and actuator devices. In general, you can see Raspberry Pi GPIO pinouts in the following figure:

To access Raspberry Pi GPIO, we can use several GPIO libraries. If you are working with Python, Raspbian has already installed the RPi.GPIO library to access Raspberry Pi GPIO. You can read more about RPi.GPIO at https://pypi.python.org/pypi/RPi.GPIO. You can verify the RPi.GPIO library from a Python terminal by importing the RPi.GPIO module.

If you don’t find this library on Python at runtime or get the error message ImportError: No module named RPi.GPIO, you can install it by compiling from the source code. For instance, if we want to install RPi.GPIO 0.5.11, type the following commands:

wget https://pypi.python.org/packages/source/R/RPi.GPIO/RPi.GPIO-0.5.11.tar.gz

tar -xvzf RPi.GPIO-0.5.11.tar.gz

cd RPi.GPIO-0.5.11/

sudo python setup.py install

To install and update through the apt command, your Raspberry Pi must be connected to the Internet.

Another way to access Raspberry Pi GPIO is to use WiringPi. It is a library written in C for Raspberry Pi to access GPIO pins. You can read more about WiringPi at http://wiringpi.com/.

To install WiringPi, you can type the following commands:

sudo apt-get update

sudo apt-get install git-core

git clone git://git.drogon.net/wiringPi

cd wiringPi

sudo ./build

Please make sure that your Pi network does not block the git protocol for git://git.dragon.net/wiringPi. You can browsed https://git.drogon.net/?p=wiringPi;a=summary for this code.

The next step is to install the WiringPi interface for Python, so you can access Raspberry Pi GPIO from the Python program. Type the following commands:

sudo apt-get install python-dev python-setuptools

git clone https://github.com/Gadgetoid/WiringPi2-Python.git

cd WiringPi2-Python

sudo python setup.py install

When finished, you can verify it by showing GPIO map from the Raspberry Pi board using the following gpio tool:

gpio readall

You should see the GPIO map from the Raspberry Pi board on the terminal.

You can also see values in the wPi column, which will be used in the WirinPi program as GPIO value parameters. In this book, you can find more information about how to use it on the WiringPi library.

What you need for this book?

We are going to use Raspberry Pi 2 board Model B. To make Raspberry Pi work, we need OS that acts as a bridge between the hardware and the user. There are many OS options that you can use for Raspberry Pi. This book uses Raspbian for the OS platform for Raspberry Pi. To deploy Raspbian on Raspberry Pi 2 Model B, we need microSD card of at least 4 GB size.

Who this book is written for?

This book is for those who want to learn how to build Raspberry Pi projects using LEDs, 7-segment, 4-digit 7-segment, and dot matrix modules. You will also learn to implement those modules in real applications, including interfacing with wireless modules and the Android mobile app. However, you don't need to have any previous experience with the Raspberry Pi or Android platforms.

Summary

In this article, we learned different techniques to install Raspberry Pi GPIO. Read Raspberry Pi LED Blueprints to start designing and implementing several projects based on LEDs, such as 7-segments, 4-digit 7-segment, and dot matrix displays.

Other related titles are:

• Raspberry Pi Blueprints
• Raspberry Pi Super Cluster
• Learning Raspberry Pi
• Raspberry Pi Robotic Projects

Resources for Article:

Further resources on this subject:

• Color and motion finding [article]
• Basic Image Processing [article]
• Develop a Digital Clock [article]