To get the most out of this book
The software used in this book is entirely open source. In almost all cases, I have used the latest stable versions available at the time of writing. While I have tried to describe the main features in a manner that is not version-specific, it is inevitable that some of the examples will need adaptation to work with later software.
* See the Compatible Linux Distribution section of the Yocto Project Quick Build guide at https://www.yoctoproject.org/docs/current/brief-yoctoprojectqs/brief-yoctoprojectqs.html for more details.
Embedded development involves two systems: the host, which is used for developing the programs, and the target, which runs them. For the host system, I have used Ubuntu 20.04 LTS, but most Linux distributions will work with just a little modification. You may decide to run Linux as a guest in a virtual machine, but you should be aware that some tasks, such as building a distribution using the Yocto Project, are quite demanding and are better run on a native installation of Linux.
I chose three exemplar targets: the QEMU emulator, the BeagleBone Black, and the Raspberry Pi 4. Using QEMU means that you can try out most of the examples without having to invest in any additional hardware. On the other hand, some things work better if you do have real hardware, for which, I have chosen the BeagleBone Black because it is not expensive, it is widely available, and it has very good community support. The Raspberry Pi 4 was added in the third edition for its built-in Wi-Fi and Bluetooth. Of course, you are not limited to just these three targets. The idea behind the book is to provide you with general solutions to problems so that you can apply them to a wide range of target boards.
