Book Image

Yocto for Raspberry Pi

By : TEXIER Pierre-Jean, Petter Mabäcker
Book Image

Yocto for Raspberry Pi

By: TEXIER Pierre-Jean, Petter Mabäcker

Overview of this book

The Yocto Project is a Linux Foundation workgroup, which produces tools (SDK) and processes (configuration, compilation, installation) that will enable the creation of Linux distributions for embedded software, independent of the architecture of embedded software (Raspberry Pi, i.MX6, and so on). It is a powerful build system that allows you to master your personal or professional development. This book presents you with the configuration of the Yocto Framework for the Raspberry Pi, allowing you to create amazing and innovative projects using the Yocto/ OpenEmbedded eco-system. It starts with the basic introduction of Yocto's build system, and takes you through the setup and deployment steps for Yocto. It then helps you to develop an understanding of Bitbake (the task scheduler), and learn how to create a basic recipe through a GPIO application example. You can then explore the different types of Yocto recipe elements (LICENSE, FILES, SRC_URI, and so on). Next, you will learn how to customize existing recipes in Yocto/OE layers and add layers to your custom environment (qt5 for example).
Table of Contents (18 chapters)
Yocto for Raspberry Pi
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
3
Mastering Baking with Hob and Toaster

Controlling the relay using the Raspberry Pi


To start with, we will control only the relay from the Raspberry Pi connected to it. This will be done using GPIO pins. First, we need to connect the relay to our Raspberry Pi in the correct way. The following table shows the connection scheme:

Wire (color

GPIO pin

Relay pin

Red

3.3V (pin 1)

Power/VCC (+)

Black

GND (pin 6)

GND (-)

Yellow

GPIO 17 (pin 11)

IN (Signal/S)

When this scheme is physically applied, it will look like the following figure. Remember that the exact order of the relay pins might look different between different models.

A Raspberry Pi 2 connected to a one-channel relay module, using GPIO 17 for the signaling

When the connection to the relay is complete, we can continue with next step: turning on or off the small LED connected to the relay. Most relays have a small LED attached to them. If your relay doesn't have an LED indicator, don't worry; we will look at some methods of checking from the command line whether...