The following hardware will be needed in order to derive the most from this chapter and the rest of this book:

• A target device (Raspberry Pi 3B+) with supporting hardware. See the Embedded Hardware and Firmware Setup section for more information.
• A host development PC running Ubuntu 16.04 or higher. This can be running directly on a PC or in a VM with network access. Other Linux distributions may work, but this book is written for Ubuntu. (I am running Ubuntu 18.10 on dedicated hardware.) You will need the following access rights for your account on the host:
  • Administrative (or root) privileges for installing software on your development PC are needed.
  • A web browser (Chrome is recommended) is required.
  • Internet access is necessary.
  • The following tools should be configured and working on the host:
    • ssh
    • rsync
    • scp
    • tar
    • xz
    • bzip2
    • g++
    • patch
  • The Host...

As much as I would like to get right down to writing software, there are some hardware issues that need to be taken care of first. I chose to cover this first so that you have time to get everything together before you need to use it.

The Raspberry Pi 3B+ was chosen because of its low cost, high availability, and good community support. We will also be using the Raspberry Pi 7" touchscreen display and a Raspberry Pi Sense HAT. Additionally, you will want a USB keyboard, USB mouse (optional), power supply for the Raspberry Pi, and a 16 or 32 GB micro SD card.

You will also want a network connection between your Raspberry Pi and your development host. If possible, you will want the Raspberry Pi on the same network that your host uses for its network access; however, you may also choose to add an additional network interface to your...

In this section, we will look at setting up the Linux host PC so that we can easily develop Qt applications.

Qt comes in two basic licenses—Commercial and Open Source. We will be using the Open Source version.

Qt can be download from https://qt.io/dowownload. Make sure to download the Linux version of the online installer for the Open Source version.

While Qt can sometimes be obtained for a specific target, the version we are running isn't available for the Raspberry Pi. Instead, we will look at how to build Qt from the sources. At first, it may seem like a daunting task, but it really is straightforward. Let's get to it:

1. Before we start building Qt, we are going to make a backup copy of the source directory using tar. Open Command Prompt and cd to the installation directory for Qt 5.12.0. Next, tar up the Src directory, as follows:

[On Host] $ cd ~/Qt/5.12.0
[On Host] $ tar jcvf qt-5.12.0-src.tar.bz2 Src

2. Now, extract the tarball into ~/raspi/Src and rename it ...

If you've made it this far, your Qt for IoT Development environment and hardware should all be ready to go. Let's run a quick test to make sure this is the case. I've written a short test program to verify the basic setup of the Raspberry Pi itself. It can be found in the Git repository for this book. Download the single executable, C01_01-ItWorks, to ~/raspi. Transfer it to the device and then execute it. Then, follow these steps:

1. On the host PC, enter the following command:

[On Host] $ scp ~/raspi/C01_01-ItWorks root@raspberrypi:/home/root

2. Then, ssh into the Raspberry Pi and start it:

[On Target] $ /root/C01_01-ItWorks

3. You should now see a picture with the words It Works! on the display. If not, verify your installation steps:

You can hit Ctrl+C in the ssh connection to terminate the program...

In this chapter, we learned how to set up a Raspberry Pi 3B+ for embedded Qt development. We also learned how to prepare a Linux host PC for cross compilation for the Raspberry Pi Target. We explored how to pull the parts of the root filesystem that are needed for development from the Target. Together, we also learned how to configure and build Qt from its source code and then push the updated root filesystem to the Target.

While we have only dealt with one particular Target, working with applications for other target systems is fairly straightforward. The differences will be in what initial target image you select, the cross compiling tool chain, and the way Qt is configured. Hopefully, by working through this chapter, you will be confident enough to be able to do it for any system you find.

In Chapter 2, Writing Your First Qt Application, we will write our first Qt program...

1. Qt is available under what types of licenses? How are they different?
2. What project allows you to custom build a Linux distribution for embedded use?
3. How do you prepare to build Qt from its source code?
4. What command can be used to synchronize directories across remote machines?
5. What are two methods for sharing filesystems between remote machines?
6. Is it okay to use the Qt version that's installed through Ubuntu? Why?
7. What are the major steps that are needed to prepare Qt for working on a new device?
8. How can you identify the device that's assigned to an SD card?

You may also find the following Packt books to be useful regarding your learning experience:

• Embedded Linux Development using Yocto Projects – Second Edition, by Otavio Salvador and Daiane Angolini
• Embedded Linux Development Using Yocto Project Cookbook – Second Edition, by Alex González