The RPi models are capable general-purpose computing devices, and for that reason they have found favor for introducing learners to general computing and computer programming. The RPi models, some of which are illustrated in Figure 1-1, are also capable physical computingdevices that can be used for embedded systems applications—and for Internet-attached embedded applications in particular.
Some general characteristics of RPi devices include the following:
- They are low cost, available for as little as $5–$35.
- They are powerful computing devices. For example, the RPi 3 contains a 1.2 GHz ARM Cortex-A53 processor that can perform more than 700 million Whetstone instructions per second (MWIPS).
- They are available in a range of models that are suitable for different applications (e.g., the larger-format RPi 3 for prototyping and the tinyformat RPi Zero or Compute Module for deployment).
- They support many standard interfaces for electronic devices.
- They use little power, running at between approximately 0.5 W (RPi Zero when idle) and approximately 5.5 W (RPi 3 under load).
- They are expandable through the use of Hardware Attached on Top (HAT) daughter boards and USB devices.
- They are supported by a huge community of innovators and enthusiasts, who generously give of their time to help the RPi Foundation with their educational mission.
The RPi platform can run the Linux operating system, which means that you can use many open source software libraries and applications directly with it. Open source software driver availabilityalso enables you to interface devices such as USB cameras, keyboards, and Wi-Fi adapters with your project, without having to source proprietary alternatives.
Therefore, you have access to comprehensive libraries of code that have been built by a talented open source community; however, it is important to remember that the code typically comes without any type of warranty or guarantee. If there are problems, you have to rely on the good nature of the community to resolve them. Of course, you could also fix the problems yourself and make the solutions publicly available.
One impressive feature of recent RPi models is that their functionality can be extended with daughter boards, called HATs(Hardware Attached on Top), that connect to the GPIO header (the 40-pin double-pin connector row on the boards in Figure 1-1). You can design your own HATs and attach them securely to your RPi using this header. In addition, many HATs are available for purchase that can be used to expand the functionality of your RPi platform. Some examples of these are described toward the end of this chapter.
Who Should Use the RPi
Anybody who wants to transform an engineering concept into a real interactive electronics project, prototype, or work of art should consider using the RPi. That said, integrating high-level software and low-level electronics is not an easy task. However, the difficulty involved in an implementation depends on the level of sophistication that the project demands. The RPi community is working hard to ensure that the platform is accessible by everyone who is interested in integrating it into their projects, whether they are students, makers, artists, or hobbyists. For example, the availability of the Scratch visual programming tool on the RPi (tiny.cc/erpi101) is an excellent way to engage children with both computer programming and the RPi.
For more advanced users with electronics or computing knowledge, the RPi platform enables additional development and customization to meet specific project needs. Again, such customization is not trivial: You may be an electronics expert, but high-level software programming and/or the Linux operating system might cause you difficulty. Or you may be a programming guru but you have never wired an LED! This book aims to cater to all types of users who are interested in interfacing with the RPi, providing each type of reader with enough Linux, electronics, and software exposure to ensure that you can be productive, regardless of your previous experience level.
