BeagleBone Black Cookbook

BeagleBone Black Cookbook

Overview of this book

There are many single-board controllers and computers such as Arduino, Udoo, or Raspberry Pi, which can be used to create electronic prototypes on circuit boards. However, when it comes to creating more advanced projects, BeagleBone Black provides a sophisticated alternative. Mastering the BeagleBone Black enables you to combine it with sensors and LEDs, add buttons, and marry it to a variety of add-on boards. You can transform this tiny device into the brain for an embedded application or an endless variety of electronic inventions and prototypes. With dozens of how-tos, this book kicks off with the basic steps for setting up and running the BeagleBone Black for the first time, from connecting the necessary hardware and using the command line with Linux commands to installing new software and controlling your system remotely. Following these recipes, more advanced examples take you through scripting, debugging, and working with software source files, eventually working with the Linux kernel. Subsequently, you will learn how to exploit the board's real-time functions. We will then discover exciting methods for using sound and video with the system before marching forward into an exploration of recipes for building Internet of Things projects. Finally, the book finishes with a dramatic arc upward into outer space, when you explore ways to build projects for tracking and monitoring satellites.

BeagleBone Black Cookbook

Credits

About the Author

About the Reviewers

www.PacktPub.com

Preface

Free Chapter

Setting Up for the First Time

Introduction

First boot up

Power requirements – basic guidelines

Display

Essential GNU/Linux commands – the command shell

Essential GNU/Linux commands – typical commands

Edit a text file from the command shell

Connectivity

Package management – Installing packages using apt-get

SSH / Remote access

System images

Basic Programming Recipes

Introduction

Introduction to BoneScript

Toggle LED

Using the Cloud9 IDE

Node.js basic recipes

Adding a new module to Node.js

Using Node.js with Johnny-Five

Python basic recipes

Adding libraries

Running a Python script to control the LEDs

Physical Computing Recipes Using JavaScript, the BoneScript Library, and Python

Introduction

Controlling external LEDs

Using buttons – button press function

Using analog sensors

Variable resistance sensor – photocell

Using motors

Exploring GNU/Linux Recipes Using Bash, Autotools, Debugger, and systemd

Introduction

The basic shell script

Epoch Time shell script

Compile and install

Compile and install Git from source

Debugging

Debug a simple C-code application from the command line using GDB

Debug an application remotely from Eclipse and GDB server

systemd services

Basic commands for systemd services

Optimize boot time

Create a systemd service to run at boot time

Basic Programming Recipes with the Linux Kernel

Introduction

Kernel application binary interface

Installing the latest kernel image

Installing and building a custom kernel

Interactions with the kernel – sysfs entries and controlling the GPIOs

Device Tree and its roots

Device Tree / basic build

Device Tree / advanced – adding DT overlay to run a custom cape

Universal cape overlay

Running a script to check DT usage on GPIO pins

Run Faster, Run Real Time

Introduction

Installing a test tool

Modifying the kernel using RT-PREEMPT

Modifying the kernel using Xenomai

Programmable real-time units – an introduction

A simple PRU test with an assembler

Running an ultrasonic range sensor with the PRUs

Using Python with the PRUs

Applied Recipes – Sound, Picture, and Video

Introduction

Wiring up a mini amp and speakers

Creating a high-quality audio platform with Volumio

Using videos and displays in projects

Testing a mini LCD cape

Making a video chat client prototype using Linphone

The Internet of Things

Introduction

Location-based recipes – hooking up GPS

Location-based recipes – Bluetooth LE and Beacons

Using sensors and data with ThingSpeak

Making things smarter – building a wireless digital picture frame

The Black in Outer Space

Introduction

Grabbing the International Space Station flyover data and visualizing it

Tracking using RTL-SDR

Airplane tracking with RTL-SDR

Satellite tracking using GPredict and RTL-SDR

Satellite tracking using the SatNogs Network client / ground station and RTL-SDR

Adding other interfaces – ISS tracking and text to speech

Index

Customer Reviews

5 star

4 star

3 star

2 star

1 star

Optimize boot time

You can use systemd to speed up your startup time. This recipe is not a definitive recommendation for which services may be expendable. Instead, it provides the overall method to test the impact of different services on your boot time.

How to do it...

Perform the following steps:

Navigate to the systemd directory (root user) as follows:
```
# cd /lib/systemd/system
```
Next, determine how long your overall system is taking to get going with the following code:
```
# systemd-analyze
```
You can quickly figure out the pokier services. Just point the finger at them with the following command that reveals all the systemd services that are sorted by their boot times:
```
# systemd-analyze blame
```
From this output, you can immediately pinpoint some of the culprits. We will assume that you're running the current Debian distro, so you'll see things similar to the following command:
```
wicd.service (7205ms)
apache2.service (3430ms)
wpa_supplicant.service (1938ms)
...
```
Some of these may be expendable startup...

BeagleBone Black Cookbook

BeagleBone Black Cookbook

Overview of this book

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Current Title:

BeagleBone Black Cookbook

Optimize boot time

How to do it...