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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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ADCs in Linux

To explain the functioning of ADCs in a GNU/Linux-based system, let's use the SAMA5D3 Xplained board since its ADC support is more complete than the BeagleBone Black's (however, during the explanation, each difference with the BeagleBone Black will be pointed out).

If we take a look at the iio:device0 directory's content in the SAMA5D3 Xplained, we will find the listing shown here:

root@a5d3:~# ls /sys/bus/iio/devices/iio\:device0/
buffer           in_voltage1_raw in_voltage6_raw  name         trigger
dev              in_voltage2_raw in_voltage7_raw  of_node      uevent
in_voltage0_raw  in_voltage3_raw in_voltage8_raw  power
in_voltage10_raw in_voltage4_raw in_voltage9_raw  scan_elements
in_voltage11_raw in_voltage5_raw in_voltage_scale subsystem

Files in the in_voltageX_raw form can be used to read a single ADC input from a particular channel. This interface can be used, as shown here:

root@a5d3:~# cat /sys/bus/iio/devices/iio\:device0/in_voltage0_raw
1662

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