Book Image

GNU/Linux Rapid Embedded Programming

By : Rodolfo Giometti
Book Image

GNU/Linux Rapid Embedded Programming

By: Rodolfo Giometti

Overview of this book

Embedded computers have become very complex in the last few years and developers need to easily manage them by focusing on how to solve a problem without wasting time in finding supported peripherals or learning how to manage them. The main challenge with experienced embedded programmers and engineers is really how long it takes to turn an idea into reality, and we show you exactly how to do it. This book shows how to interact with external environments through specific peripherals used in the industry. We will use the latest Linux kernel release 4.4.x and Debian/Ubuntu distributions (with embedded distributions like OpenWrt and Yocto). The book will present popular boards in the industry that are user-friendly to base the rest of the projects on - BeagleBone Black, SAMA5D3 Xplained, Wandboard and system-on-chip manufacturers. Readers will be able to take their first steps in programming the embedded platforms, using C, Bash, and Python/PHP languages in order to get access to the external peripherals. More about using and programming device driver and accessing the peripherals will be covered to lay a strong foundation. The readers will learn how to read/write data from/to the external environment by using both C programs or a scripting language (Bash/PHP/Python) and how to configure a device driver for a specific hardware. After finishing this book, the readers will be able to gain a good knowledge level and understanding of writing, configuring, and managing drivers, controlling and monitoring applications with the help of efficient/quick programming and will be able to apply these skills into real-world projects.
Table of Contents (26 chapters)
GNU/Linux Rapid Embedded Programming
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface

The I2C bus in Linux


Each I2C device has a well defined 7 bits address that the master must use in order to communicate with a device. This address is not assigned at runtime as for the USB devices, it's assigned by the board designer by setting some chip's pins.

Note

Typically the chip manufacturer set most significant 3 or 4 bits and the board designer can set remaining bits in order to suite his/her needs. I2C bus specifications are controlled by NXP (Philips) and they are the ones who allocate addresses to I2C devices.

Another thing to be outlined regarding the I2C bus is that for each message the master must specify if the message wants read or write data from the slave. This special action is done by adding a final bit (least significant bit) to the slave address, the master uses a 0 to write data and a 1 to read data from the slave.

As for the USB bus we still have two main actors: master and slave. So in the kernel we find both the device driver types.

Regarding I2C master device there...