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  • Book Overview & Buying GNU/Linux Rapid Embedded Programming
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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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PWM devices in Linux

Let's use the BeagleBone Black to see how a PWM device works (the steps that follow are almost the same for the SAMA5D3 Xplained and other GNU/Linux supporting these devices). We saw earlier that for each PWM generator, we have a well-defined directory in /sys/class/pwm/. In our case, we have the directory named pwmchip0. Then, by taking a look at its contents, we can find the following items:

root@bbb:~# ls /sys/class/pwm/pwmchip0/
device/   export    npwm      power/    subsystem/ uevent     unexport

You can notice that this representation is quite similar to the GPIO controllers we saw in the GPIOs in Linux section, in Chapter 6General Purposes Input Output signals – GPIO . So, the export and unexport files are used to export and unexport the PWMs, respectively, while in npwm, we have the number of PWM lines we can manage within the PWM chip. As expected, in the command line here, we see that we can manage two PWM signals within the pwmchip0...

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