Introduction
This chapter introduces Raspberry Pi 3 and the process of setting it up for the first time. We will connect Raspberry Pi to a suitable display, power, and peripherals. We will install an operating system on an SD card. This is required for the system to boot. Next, we will ensure that we can connect successfully to the internet through a local network.
Finally, we will make use of the network to provide ways to remotely connect to and/or control Raspberry Pi from other computers and devices, as well as to ensure that the system is kept up to date.
Once you have completed the steps within this chapter, your Raspberry Pi will be ready for you to use for programming. If you already have your Raspberry Pi set up and running, ensure that you take a look through the following sections, as there are many helpful tips.
Introducing Raspberry Pi
The Raspberry Pi is a single-board computer created by the Raspberry Pi Foundation, a charity formed with the primary purpose of re-introducing low-level computer skills to children in the UK. The aim was to rekindle the microcomputer revolution of the 1980s, which produced a whole generation of skilled programmers.
Even before the computer was released at the end of February 2012, it was clear that Raspberry Pi had gained a huge following worldwide and, at the time of writing this book, has sold over 10 million units. The following image shows several different Raspberry Pi models:
The Raspberry Pi Model 3B, Model A+, and Pi Zero
What's with the name?
The name, Raspberry Pi, was a combination of the desire to create an alternative computer with a fruit-based name (such as Apple, BlackBerry, and Apricot) and a nod to the original concept of a simple computer that could be programmed using Python (shortened to Pi).
In this book, we will take this little computer, find out how to set it up, and then explore its capabilities chapter by chapter, using the Python programming language.
Why Python?
It is often asked, "Why has Python been selected as the language to use on Raspberry Pi?" The fact is that Python is just one of the many programming languages that can be used on Raspberry Pi.
There are many programming languages that you can choose, from high-level graphical block programming, such as Scratch, to traditional C, right down to BASIC, and even the raw machine code assembler. A good programmer often has to be code multilingual to be able to play to the strengths and weaknesses of each language to best meet the needs of their desired application. It is useful to understand how different languages (and programming techniques) try to overcome the challenge of converting what you want into what you get, as this is what you are trying to do as well while you program.
Python has been selected as a good place to start when learning about programming, as it provides a rich set of coding tools while still allowing simple programs to be written without fuss. This allows beginners to gradually be introduced to the concepts and methods on which modern programming languages are based without requiring them to know it all from the start. It is very modular with lots of additional libraries that can be imported to quickly extend the functionality. You will find that, over time, this encourages you to do the same, and you will want to create your own modules that you can plug into your own programs, thus taking your first steps into structured programming.
Python addresses formatting and presentation concerns. As indentation will add better readability, indents matter a lot in Python. They define how blocks of code are grouped together. Generally, Python is slow; since it is interpreted, it takes time to create a module while it is running the program. This can be a problem if you need to respond to time-critical events. However, you can precompile Python or use modules written in other languages to overcome this.
It hides the details; this is both an advantage and a disadvantage. It is excellent for beginners but can be difficult when you have to second-guess aspects such as datatypes. However, this in turn forces you to consider all the possibilities, which can be a good thing.
Python 2 and Python 3
A massive source of confusion for beginners is that there are two versions of Python on Raspberry Pi (Version 2.7 and Version 3.6), which are not compatible with each other, so code written for Python 2.7 may not run with Python 3.6 (and vice versa).
The Python Software Foundation is continuously working to improve and move forward with the language, which sometimes means they have to sacrifice backward compatibility to embrace new improvements (and, importantly, remove redundant and legacy ways of doing things).
Note
Supporting Python 2 and Python 3
There are many tools that will ease the transition from Python 2 to Python 3, including converters such as2to3, which will parse and update your code to use Python 3 methods. This process is not perfect, and in some cases you'll need to manually rewrite sections and fully retest everything. You can write the code and libraries that will support both. Theimport __future__statement allows you to import the friendly methods of Python 3 and run them using Python 2.7.
Which version of Python should you use?
Essentially, the selection of which version to use will depend on what you intend to do. For instance, you may require Python 2.7 libraries, which are not yet available for Python 3.6. Python 3 has been available since 2008, so these tend to be older or larger libraries that have not been translated. In many cases, there are new alternatives to legacy libraries; however, their support can vary.
In this book, we have used Python 3.6, which is also compatible with Python 3.5 and 3.3.
The Raspberry Pi family – a brief history of Pi
Since its release, Raspberry Pi has come in various iterations, featuring both small and large updates and improvements to the original Raspberry Pi Model B unit. Although it can be confusing at first, there are three basic types of Raspberry Pi available (and one special model).
The main flagship model is called Model B. This has all the connections and features, as well as the maximum RAM and the latest processor. Over the years, there have been several versions, most notably Model B (which had 256 MB and then 512 MB RAM) and then Model B+ (which increased the 26-pin GPIO to 40 pins, switched to using a microSD card slot, and had four USB ports instead of two). These original models all used the Broadcom BCM2835 system on chip (SOC), consisting of a single core 700 MHz ARM11 and VideoCore IV graphical processing unit (GPU).
The release of Raspberry Pi 2 Model B (also referred to as 2B) in 2015 introduced a new Broadcom BCM2836 SOC, providing a quad-core 32-bit ARM Cortex A7 1.2 GHz processor and GPU, with 1 GB of RAM. The improved SOC added support for Ubuntu and Windows 10 IoT. Finally, we had the latest Raspberry Pi 3 Model B, using another new Broadcom BCM2837 SOC, which provides a quad-core 64-bit ARM Cortex-A53 and GPU, alongside on-board Wi-Fi and Bluetooth.
Model A has always been targeted as a cut-down version. While having the same SOC as Model B, there are limited connections consisting of a single USB port and no wired network (LAN). Model A+ again added more GPIO pins and a microSD slot. However, the RAM was later upgraded to 512 MB of RAM and again there was only a single USB port/no LAN. The Broadcom BCM2835 SOC on Model A has not been updated so far (so is still a single core ARM11); however, a Model 3A (most likely using the BCM2837).
The Pi Zero is an ultra-compact version of Raspberry Pi intended for embedded applications where cost and space are a premium. It has the same 40-pin GPIO and microSD card slot as the other models, but lacks the on-board display (CSI and DSI) connection. It does still have HDMI (via a mini-HDMI) and a single micro USB on-the-go (OTG) connection. Although not present in the first revision of the Pi Zero, the most recent model also includes a CSI connection for the on-board camera.
Note
Pi Zero was famously released in 2015 and was given away with Raspberry Pi foundation's magazine The MagPi, giving the magazine the benefit of being the first magazine to give away a computer on its cover! This did make me rather proud since (as you may have read in my biography at the start of this book) I was one of the founders of the magazine.
The special model is known as the compute module. This takes the form of a 200-pin SODIMM card. It is intended for industrial use or within commercial products, where all the external interfaces would be provided by a host/motherboard, into which the module would be inserted. Example products include the Slice Media Player (http://fiveninjas.com) and the OTTO camera. The current module uses the BCM2835, although an updated compute module (CM3).
The Raspberry Pi Wikipedia page provides a full list of the all different variants and their specifications:https://en.wikipedia.org/wiki/Raspberry_Pi#Specifications
Also, the Raspberry Pi product page gives you the details about the models available and the accessories' specifications:https://www.raspberrypi.org/products/
Which Pi to choose?
All sections of this book are compatible will all current versions of Raspberry Pi, but Model 3B is recommended as the best model to start with. This offers the best performance (particularly useful for the GPU examples in OpenCV examples used in Chapter 5, Detecting Edges and Contours in Images), lots of connections, and built-in Wi-Fi, which can be very convenient.
Pi Zero is recommended for projects where you want low power usage or reduced weight/size but do not need the full processing power of Model 3B. However, due to its ultra-low cost, Pi Zero is ideal for deploying a completed project after you have developed it.
