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GNU/Linux Rapid Embedded Programming

GNU/Linux Rapid Embedded Programming

By : Rodolfo Giometti
4.3 (3)
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GNU/Linux Rapid Embedded Programming

GNU/Linux Rapid Embedded Programming

4.3 (3)
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 (20 chapters)
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The Raw I2C Bus


Now, as done for USB bus we should take a look at how we can get direct access to the I2C bus. In the same manner as for USB devices when one of them hasn't a dedicated driver it can be managed directly from the user space. The only problem may arise if the I2C device can generate interrupts, in this case we cannot manage these signals from the user-space and a kernel driver must be used. However this is a rare case and the presented technique can be used in most cases.

Writing data in C

As first example we're going to write some data to the DAC chip named TC1321 which is mounted on the development board we used above connected to the BeagleBone Black board.

Note

The datasheet is available at the URL: http://ww1.microchip.com/downloads/en/DeviceDoc/21387C.pdf

By looking at the chip's datasheet we see that its functioning is very simple: it has one 16-bit register at offset 0x00 where we can write digital data to be converted. In fact the register has the format reported below...

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