Innholdsfortegnelse for Issue 5 i Raspberry Pi Coding & Projects The Complete Manual

HAT & GPIO Interface The Raspberry Pi is made with expansion in mind. External peripherals and items are often attached here. ‘HAT’ stands for Hardware Attached on Top’, which is where many things connected to the Pi sit, and GPIO is ‘General Purpose In/Out’, which refers to the data flow from and to the Pi. Powerful CPU The Raspberry Pi 5 is powered by a 64-bit quad-core Arm Cortex-A76 processor running at 2.4GHz, giving a performance boost of between two and three times what the Raspberry Pi 4 could achieve. It also has a Broadcom VideoCore VII GPU. Power Button With previous Raspberry Pi models, to turn it off and turn it on again you had to pull the power lead out or switch it off at the mains. At…

FASTER AND CONNECTED There’s a lot to like about the Raspberry Pi 4: Up to 8GB of on-board memory, a faster quad-core CPU, support for dual 4K displays via a pair of micro-HDMI ports, and more. Let’s take a look at the Pi 4, and see what it’s got under-the-hood. Improved GPU With a VideoCore 6 GPU, the Pi 4 is capable of 4K resolutions at 60FPS (Frames per Second), and thanks to some tweaks to the video codes in both Raspberry Pi OS and the version of VLC packaged with Raspberry Pi OS, the Pi 4 is now a pretty decent media device. Improved Processing The 1.5GHz, 64-bit quad-core ARM Cortex-A72 CPU, is the driving force behind the Pi 4’s improved performance. Thanks to this CPU, you’re able to…

EVERYONE LOVES PI We’ve put together ten possible projects that you could use your Pi 400 with; that will entertain and keep you busy while helping you learn more about coding, the Pi and computing. RETRO COMPUTING With the Pi 400 being very similar to that of the great home computers of the 80s, we thought we’d start these ideas with a simple retro-themed project. Fuse is a ZX Spectrum emulator that’s available for the Raspberry Pi. Install it, and you can enjoy some of the greatest games ever created. STREAM PC GAMES It’s possible to stream any game installed on your powerful gaming PC to a Raspberry Pi. All you need is to ensure that your home network is up to scratch – use Ethernet connections between the two…

The Pico uses MicroPython or C/C++ code in order to communicate with the devices it will be attached to. The code will, when uploaded to the Pico, run a specific set of instructions depending on the electronics that are soldered to the Pico. For example, in MicroPython, with an LED attached to the Pico, you would initialise and import the Pin and Timer modules, tell the Pico which GPIO the LED is attached to, then setup a routine that will use the Timer function to send a signal to the LED – let’s say every couple of seconds. The end result would be a blinking LED, which goes on and off every two seconds. Naturally, the more complex the electronics attached to the Pico are, then the more complex the…

An SBC, or Single-Board Computer, is a complete computer system that’s built on a single piece of circuit board; consisting of memory, storage and input and output ports. The Raspberry Pi is a prime example of a modern SBC, and the one that has easily become the most popular available in an increasingly crowded marketplace. However, there are a number of other SBCs available that vary in size, capacity, performance, price and expandability. Some of them are x86-based, which means they’re basically very small PCs on which you can install Windows 10; others utilise different makes of processor or microprocessors and offer a varied number of operating systems that will work on them, such as Android or Linux. While the Raspberry Pi is the SBC that offers some of the…

ASK AROUND The kit list required to set up a Raspberry Pi is pretty basic: keyboard, mouse, HDMI monitor, SD Card and an optional case. Many of these items you’ll already have, but don’t rush out and buy those you don’t. Ask around to see if anybody you know has spares. STEP 1 The most important thing you need is an SD Card. These are the storage cards commonly found in digital cameras. All modern Raspberry Pi boards, including the Raspberry Pi 3 and Pi Zero, use Micro SD cards but the older boards may use a larger SD Card. STEP 2 The SD Card plugs into the SD Card socket. On the Raspberry Pi 4, 3, and Pi Zero, you push the card in and pull it out. On…

CUSTOM TERMINAL The Terminal gives you access to the command line, where the real power of the Linux OS lies. Getting used to the Terminal is key to mastering the Pi and your projects. STEP 1 Start Terminal by clicking the Terminal icon in the Application Launch Bar. You can also start Terminal by pressing Control-Alt-T or choosing Menu > Accessories > Terminal. Terminal emulates the old style video terminals from before desktop interfaces; so by default it displays bright (mostly green) on a black background. STEP 2 The first thing most people overlook is the ability to run multiple terminals at once in different tabs. Choose File > New Tab (Shift-Control-T) to create a new tab. Navigating multiple directories simultaneously can be a challenge in Terminal and tabs makes…

EDITING CODE You will eventually reach a point where you have to move on from inputting single lines of code into the Shell. Instead, the IDLE Editor will allow you to save and execute your Python code. STEP 1 First, open the Python IDLE Shell and when it’s up, click on File > New File. This will open a new window with Untitled as its name. This is the Python IDLE Editor and within it you can enter the code needed to create your future programs. STEP 2 The IDLE Editor is, for all intents and purposes, a simple text editor with Python features, colour coding and so on; much in the same vein as Sublime. You enter code as you would within the Shell, so taking an example from…

FUNKY FUNCTIONS A function is a command that you enter into Python to do something. It’s a little piece of self-contained code that takes data, works on it and then returns the result. STEP 1 It’s not just data that a function works on. They can do all manner of useful things in Python, such as sort data, change items from one format to another and check the length or type of items. Basically, a function is a short word that’s followed by brackets. For example, len(), list() or type(). STEP 2 A function takes data, usually a variable, works on it depending on what the function is programmed to do and returns the end value. The data being worked on goes inside the brackets, so if you wanted to…

DEBUGGING Errors in code are called bugs and are perfectly normal. They can often be easily rectified with a little patience. The important thing is to keep looking, experimenting and testing. Eventually your code will be bug free. STEP 1 Code isn’t as fluid as the written word, no matter how good the programming language is. Python is certainly easier than most languages but even it is prone to some annoying bugs. The most common are typos by the user and whilst easy to find in simple dozen-line code, imagine having to debug multi-thousand line code. STEP 2 The most common of errors is the typo, as we’ve mentioned. The typos are often at the command level: mistyping the print command for example. However, they also occur when you have…

GETTING AROUND To drop into the Terminal, click on the fourth icon from the left along the top of the Raspberry Pi desktop, the one with a right-facing arrow and an underscore. This is the shell, or Terminal. STEP 1 First, you’re going to look at directories and the directory path. A directory is the same thing as a folder, however in Linux it’s always called a directory. These are placed inside each other using a “/” character. So when you see / home/pi it means the pi directory is inside the home directory. Enter: clear and press return to clean the screen. Now enter: pwd. This stands for Print Working Directory and displays /home/pi. STEP 2 When you log in to your Raspberry Pi, you don’t start at the…

MANAGING FILES AND DIRECTORIES Now that you know how to create files, you’ll want to learn how to make directories, which are the same thing as folders, as well as move items around. If you are more used to working with a desktop interface, this can take a bit of getting used to. STEP 1 Enter: ls to quickly view all the directories currently in in the home location. Directories are created using the “mkdir” command (make directory). Enter: mkdir testdir to create a new directory in your home directory. Enter: ls again to see it. STEP 2 The “mkdir” command is different to touch, in that it doesn’t update the timestamp if you use it with a directory that already exists. Enter: mkdir testdir again and you’ll get the…

THE JOY OF TEXT You will come across a lot of text files in Linux and to be able to edit or create a text file, you need a good text editor. Linux has many but here are some in action on the Raspberry Pi. STEP 1 The first text editor for the Raspberry Pi is the default desktop environment app: Leafpad. To use, you can either double-click an existing text file or click the Raspberry Pi menu icon (in the top left of the desktop) and from the Accessories menu, choose Text Editor. STEP 2 From the Terminal there are even more options, although using the correct command, you can launch any of the desktop apps via the Terminal. One of the simplest, and a classic text editor that’s…

LOTS OF LINUX Linux is a huge and versatile command line language and there are hundreds of commands you can learn and use. Here are a few that can help you get more from your Raspberry Pi. STEP 1 The Raspberry Pi is a great little computer, so let’s start by getting some information. Enter: cat / proc/cpuinfo to view some details on your Raspberry Pi processors. If you have a Raspberry Pi 3 you will see four processors, along with the model name and other info. STEP 2 Remember that cat is used to list the contents of a text file, which is what cpuinfo is. There are other text files with system info available. Try “cat / proc/meminfo” to get information about your memory, “cat /proc/partitions” for information…

TOP 10 COMMANDS These may not be the most common commands used by everyone but they will certainly feature frequently for many users of Linux and the command line. cd The ‘cd’ command is one of the commands you will use the most at the command line in Linux. It allows you to change your working directory. You use it to move around within the hierarchy of your file system. You can also use chdir. ls The ‘ls’ command shows you the files in your current directory. Used with certain options, it lets you see file sizes, when files where created and file permissions. For example, ls ~ shows you the files that are in your home directory. cp The ‘cp’ command is used to make copies of files and…

TO BOLDLY GO… Indeed, the ISS is something most of us consider as a worthy example of what can happen when we work together. NASA, among other agencies, uses a wealth of Python code onboard the ISS to help automate routines, alongside its function as an in-between link to translate code from one language to another, and then into a human-readable format. If you’re considering a career in space, then learning Python is a must-have skill. While we’re not able to fill you in on all the details regarding the code the ISS utilises, we can look at a fun Python script that will track the ISS, display the number of astronauts on board, and update the station’s current latitude and longitude every five seconds, while also displaying your current…

ASCII ANIMATION Let’s assume you wanted to create an animated ASCII Happy Birthday Python script, with the words Happy and Birthday alternating in appearance. Here’s how it’s done. STEP 1 First we need to create some ASCII-like text, head over to http://patorjk.com/software/taag. This is an online Text to ASCII generator, created by Patrick Gillespie. Start by entering Happy into the text box, the result will be displayed in the main window. You can change the font with the drop-down menu to the side of the text box; we’ve opted for Big. STEP 2 Now, on your computer create a folder in your Python code directory (call it Test, for now) and open either Leafpad for the Raspberry Pi or, if you’re using Windows 10, then Notepad. Click on the Select…

The Raspberry Pi has come a long way since it was first released way back in February 2012. A SBC (Single Board Computer) designed to be cheap and open, it was aimed at those who want to learn about computer science by tinkering, modifying and coding. It proved way more popular than expected, with its low price and the huge wealth of Pi projects available led to people buying it for a single use rather than tinkering. Retro gamers, for example, splashed out on a Pi for playing old-school ROMs, and system managers might install one to monitor a network. Designed in Cambridge, UK, by 2015 the Raspberry Pi had overtaken the Sinclair ZX Spectrum as the best selling British computer of all time. This year’s update, the Raspberry Pi…

Inside the Pi 400 is a modified Raspberry Pi 4. It’s longer, spanning the width of the keyboard, with a large heatsink to dissipate enough heat for the overclocked processor. The Pi 4’s communication ports are spaced along the back of the Pi 400 keyboard, minus a second USB 2.0 port and a 3.5mm audio jack. 40-Pin GPIO The slightly recessed GPIO port is directly connected to the Pi 400 board inside the keyboard. This means you can still attach the usual Raspberry Pi HATs and other devices as you would a bare-metal Raspberry Pi. What’s Inside? This internal view shows the placement of the Pi board. microSD Card Slot The microSD Card Slot is where you’ll insert the card that contains the Raspberry Pi OS – or any other…

The Pi Pico may be small, but it packs a decent punch. With it you can expand your electronics projects, and incorporate a whole new level of functionality that you weren’t able to before with the traditional Raspberry Pi units. micro-USB Port The Pi Pico’s micro-USB provides both power, as well as communications between the Pico and a Raspberry Pi or other computer. Here you’ll be able to upload programs and projects on to your Pico. Boot Selection Switch The small button labelled BOOTSEL, Boot Selection, will switch the Pico between two start-up states enabling you to access the Pico as a storage device on your computer or Raspberry Pi. Memory & Storage The Pico comes with 264KB on-chip SRAM memory, as well as 2MB on-board QSPI Flash memory; to…

GETTING TO KNOW NOOBS The easiest way to get up and running is to use NOOBS, a software program created by the Raspberry Pi Foundation. You can buy a NOOBS SD Card from Raspberry Pi but it’s easy to make your own with an old unused SD Card (8GB recommended). STEP 1 We’re going to use a utility called SD Card Formatter 5 to erase the SD Card with correct formatting. You can download this app from https://www.sdcard.org/downloads/formatter_4/. Click Download SD Formatter for Mac and Accept. Click the SDFormatter.pkg file in your Downloads folder and follow the instructions to install the app. STEP 2 Use an SD Card of at least 8GB capacity to install the operating system on your Raspberry Pi. The card needs to be formatted, which will…

PIXEL PIXEL stands for “Pi Improved Xwindow Environment, Lightweight”. It’s a lightning fast and energy saving desktop that looks good too. It contains almost everything you’ll ever need to work with the Pi. THE DESKTOP The PIXEL interface is a module that’s installed on top of the core OS. It has seen some improvements over the years, and with the release of the Pi 4 and Raspberry Pi OS Buster, it now looks like this. THE PROGRAMS The programs that come pre-installed with Raspberry Pi OS are easily located by clicking on the Raspberry Pi logo in the upper left corner of the desktop. Once there, you can select from the sub-menu categories, followed by the program name. PRODUCTIVITY You’ll notice that within the Main menu, there’s a category named…

REMOTE CONTROL The Raspberry Pi is easy to set up and use in projects around the home and, surprisingly, many of these projects don’t need a keyboard, mouse or a monitor; these are known as Headless devices. VNC lets you control a Headless Pi from another computer. STEP 1 You will first need to ensure that your Pi is connected to a keyboard, mouse and monitor, and is connected to your Wi-Fi router, before you attempt to connect to it remotely. Start by clicking on the Raspberry Pi menu, then scroll down to Preferences > Raspberry Pi Configuration. STEP 2 With the Raspberry Pi Configuration window open, click on the Interfaces tab, and ensure that the VNC option is Enabled. Click on the radio button next to Enabled to activate,…

VIEWING AND MOVING FILES You can move, manage and delete files using the Command Line but like all modern operating systems Raspberry Pi OS has a program to help you manage your files. Discover how to use the File Manager app. STEP 1 Raspberry Pi OS includes a great file management program called “File Manager PCManFM” or just “File Manager” for short. Click on the FileManager PCManFM icon in the Launch Bar or choose Menu > Accessories > File Manager. STEP 2 File Manager displays the folders in your Home folder (this should match your user name, ‘Pi’ by default). By default you should have Desktop, Documents, Downloads, Music, Pictures, Public, python_games, Scratch and folders. Double-click any folder to open it and view its contents. Click the Parent Folder icon…

STARTING PYTHON For those using the Pi 4 and new Raspberry Pi OS, drop into a Terminal and enter: sudo apt-get install idle3. Older versions of Raspberry Pi OS already have the official Python IDLE pre-installed. STEP 1 With the Raspberry Pi OS desktop loaded, click on the Menu button followed by Programming > Python 3 (IDLE). This will open the Python 3 Shell. Windows and Mac users can find the Python 3 IDLE Shell from within the Windows Start button menu and via Finder. STEP 2 The Shell is where you can enter code and see the responses and output of code you’ve programmed into Python. This is a kind of sandbox, where you’re able to try out some simple code and processes. STEP 3 For example, in the…

COMMAND THE CODE Using the code we created in the previous tutorial, the one we named hello.py, let’s see how you can run code that was made in the GUI at the command line level. STEP 1 Python, in Linux, comes with two possible ways of executing code via the command line. One of the ways is with Python 2, whilst the other uses the Python 3 libraries and so on. First though, drop into the command line or Terminal on your operating system. STEP 2 Just as before, we’re using a Raspberry Pi: Windows users will need to click the Start button and search for CMD, then click the Command Line returned search; and macOS users can get access to their command line by clicking Go > Utilities >…

VARIOUS VARIABLES You’ll be working with the Python 3 IDLE Shell in this tutorial. If you haven’t already, open Python 3 or close down the previous IDLE Shell to clear up any old code. STEP 1 In some programming languages you’re required to use a dollar sign to denote a string, which is a variable made up of multiple characters, such as a name of a person. In Python this isn’t necessary. For example, in the Shell enter: name=”David Hayward” (or use your own name, unless you’re also called David Hayward). STEP 2 You can check the type of variable in use by issuing the type () command, placing the name of the variable inside the brackets. In our example, this would be: type (name). Add a new string variable:…

GOING GRAPHICAL You can draw simple graphics, lines, squares and so on, or you can use one of the many Python modules available, to bring out some spectacular effects. STEP 1 One of the best graphical modules to begin learning Python graphics is Turtle. The Turtle module is, as the name suggests, based on the turtle robots used in many schools, that can be programmed to draw something on a large piece of paper on the floor. The Turtle module can be imported with: import turtle. STEP 2 Let’s begin by drawing a simple circle. Start a New File, then enter the following code: As usual press F5 to save the code and execute it. A new window will now open up and the ‘Turtle’ will draw a circle. STEP…

LOOKING AT FILES Operating systems are built on files and folders, or directories if you prefer. While you’re used to viewing your own files, most operating systems keep other files out of sight. In Raspberry Pi OS, you have access to every file in the system. STEP 1 We’ve already looked at “ls”, which lists the files in the working directory, but you are more likely to use a command like “ls –l”. The bit after the command (the ‘-lah’) is known as the argument. This is an option that modifies the behaviour of the command. STEP 2 The “-l” argument lists files and directories in long format. Each file and directory is now on a single line, and before each file is a lot of text. First you’ll see…

USING THE MOVE COMMAND In Linux, renaming a file is simply moving it from one name to another and copying a file is moving it without deleting the original. Don’t panic, it’s quite easy to master. STEP 1 Before we can move anything around, we need to have a few test items in our home directory. Enter: touch testfile and mkdir testdir to create a test file and test directory in your home directory. Enter: ls to check that they are both present. STEP 2 Files and directories are moved using the mv command. This is different to the commands we’ve looked at so far because it has two arguments (remember Linux command line is command, option, argument). The first argument is the source (the file or directory to be…

WHAT IS A USER? An important part of using Linux is the concept of users and understanding which user you are and which group you belong to. Like all modern computers, you can have multiple user accounts with each having different levels of access. STEP 1 The first thing you need to do is get a concept of which user you are. Enter: whoami into the command line and press return. It should say “pi” (unless you set up your account name differently during setup). The “whoami” command might seem a bit simplistic, but it comes in very handy sometimes. STEP 2 When you are working in Linux, from time to time a ‘Permission denied’ error will occur, typically when you try to create, edit or execute (run) a file…

IT’S RAINING PI, HALLELUJAH! Weather stations have been available to the project-minded public since long before the Raspberry Pi entered the scene, but thanks to the Pi’s unique specifications, a new generation of weather station has emerged; and they’re really quite remarkable. As with a lot of Raspberry Pi projects, the market has become flooded with various hardware, kits, and HATs that will enable you to set up a simple, or complex, weather station. The more experienced weather station and Raspberry Pi user will probably lean toward buying in the components individually, as opposed to an entire kit, but for the rest of us the kit-form versions are an excellent start to a project that can quickly grow over time. WHY? With our smart devices connected to everything around us…

TV HAT In this tutorial, we’re using the Raspberry Pi TV HAT as sold by The Pi Hut (https://thepihut.com/products/raspberry-pi-tv-hat?variant=13539182673982). It’s a Sony CXD2880 TV Tuner supporting DVB-T and 2nd-gen DVB-T2 standards. STEP 1 The Raspberry Pi TV HAT is compatible with the Pi Zero, Pi 3 A+ and B+ models. The kit comes with everything you need to connect the HAT to your RPi, including spacers, screws and the 40-pin header. Begin by opening the box and spreading the contents out on a clear area. STEP 2 Start by connecting the 40-pin header to the 40-pin GPIO on top of your Raspberry Pi. Now take the spacers and screws and fit them to the corresponding holes in the corners of the main Raspberry Pi and the TV HAT; use three…

The Raspberry Pi is a British built low cost computer that enables everybody to learn computing, start programming and explore basic electronics. It’s the size of a credit card but capable of running a full operating system and doing everything a desktop does. More importantly, with the Raspberry Pi you install your own operating system, connect all your devices and create your own programs using languages like Scratch and Python. There’s no case so you can hook up electronic circuits to the pins and control them to get input and output, so you can hack together electronic projects at home. Setting up a Raspberry Pi is pretty simple, and throughout this book we’ll take you step-by-step from unboxing your Raspberry Pi to setting it up and getting started. There are…

40 GPIO Pins The GPIO (General Purpose Input Output) pins can be accessed directly on the Raspberry Pi. These are used in projects to connect the Raspberry Pi to electronic circuits and control electric devices. Some can be turned on and off while the Raspberry Pi is running. ARM-Powered At the heart of the Raspberry Pi 3 is a Broadcom BCM2837 System on Chip (SoC). It contains a powerful 1.2GHz 64-bit quad-core ARM Cortex-A53 CPU. This is 50-60 percent faster than the Raspberry Pi 2 and ten times as fast as the original Raspberry Pi. DSI The Display Interface (DSI) can be used to connect a display directly to the Raspberry Pi board. SD Card Slot Instead of a hard drive you use an SD Card with the Raspberry Pi.…

Released in November 2020, and while the UK and most of the world was still in lockdown, the Raspberry Pi 400 came at a time when we were beginning to feel like there was no end to the pandemic and the restrictions it brought. Initial thoughts were that the Pi 400 was a new small-board computer, in a similar vein to the Pi 4 and its predecessors. However, we were quite wrong. The Pi 400 is a very different beast to that of its siblings. Rather than the naked board we’ve seen in the past, the Pi 400 came as a complete keyboard package, with the Pi’s familiar ports lined up along the backplate of the keyboard. This in itself was remarkably reminiscent of the home microcomputers of the 80s,…

The Pico is something entirely different from the Raspberry Pi Foundation’s usual releases. Whereas the Raspberry Pi, now on version 4, is a small computer, and even the Compute Module and the Pi 400 are still just computers, the Pico is actually a microcontroller. A microcontroller is a processing unit that’s designed to work with programmable peripherals, and has input and output modules alongside a small amount of memory and storage capabilities. The processors are often scaled down, compared to the processor on a Raspberry Pi, or even inside your desktop computer, but powerful enough to complete basic tasks. Examples of a microcontroller in action can be found inside a washing machine, or traffic lights. A washing machine has no need for a quad-core processor, 8GB of memory, and the…

PICO POWER! Here are ten ideas and projects that you could look into achieving with your Raspberry Pi Pico. You may need to enhance your electronics skills, but there’s plenty of help online if you hunt around for it. ROBOTICS Can you create a Pico-powered microcontroller to work different aspects of a robot? You could use the Pico to drive the robot, or control an element on it depending on where it is in your home. TEMPERATURE GAUGE The Pico’s RP2040 processor has a built-in ADC to convert analogue to digital signals. It also has a built-in temperature sensor, so it’s possible to utilise the Pico as a temperature gauge. MOTORS In addition to the robotics idea, a Pico can be used to control motors. Again, depending on the input…

THE POWER OF PI With many different versions across four generations of models, the Raspberry Pi is certainly a busy little board. But while each Pi offers something slightly different, for the newcomer it’s a confusing medley of hardware specifications and model numbers. Which, Raspberry Pi hardware, then is going to be best for you? Naturally, that questions depends greatly on what it is you want to do with your Raspberry Pi. If you have a particular project in mind, such as a home media centre server, then you’d probably opt for the more powerful and hardware-capable model of Raspberry Pi. If you want to setup a wireless security camera project, using the Raspberry Pi as the core hardware, then perhaps the Pi Zero W would be a better fit.…

SETTING UP WITH NOOBS NOOBS (New Out Of Box Software) is a program used to make setting up a Raspberry Pi simple. You can buy SD Cards with NOOBS preinstalled, but here we’ll look at how to format your SD Card and install NOOBS using a Windows computer. STEP 1 We’re going to use a utility called SD Card Formatter to erase the SD Card with correct formatting. You can download this app from https://www.sdcard.org/downloads/formatter/eula_windows/index.html. Click the Accept button to start the download of the latest version of the software. Extract the software, and double-click the executable to install and run the app. STEP 2 We’re going to use an 8GB SD Card to install the operating system on our Raspberry Pi. The card needs to be formatted, which will…

USING TERMINAL Despite its graphical PIXEL interface, Raspberry Pi OS is a Linux operating system and this means you’ll spend a lot of time working with text commands. Using the command line is an important part of learning to use a Raspberry Pi computer. STEP 1 By default the Raspberry Pi boots directly into the PIXEL interface. Here you use a visual metaphor, files, buttons and so on, to make changes to your computer. The command line is where you control a computer by entering text commands. Click Terminal in the Menu bar to view the console. STEP 2 You can enter commands into the Terminal to make changes to the computer. This works alongside the PIXEL interface. Enter: mkdir Desktop/testfolder and press return. Notice a new folder appears below…

ADVANCED PACKAGING TOOL Add / Remove Software is great for finding and installing software but most of the time you manage apps on a Raspberry Pi using a program called APT (Advanced Packaging Tool) using the apt command. STEP 1 To manage the apps on your Raspberry Pi you’ll need to use a tool included with Raspberry Pi OS called APT (Advanced Packaging Tool). APT is a command line tool so you need to either start your Raspberry Pi in the command line or click on the Terminal icon. STEP 2 The command used to control packages in Raspberry Pi OS is apt Type apt into the terminal and press Return to get a description of what the app does. The instructions tell us that the “most frequently used commands…

GET TO KNOW GIMP Your Raspberry Pi can display images with its built-in Image View app but for any image editing you’ll need GIMP (GNU Image Manipulation Program). GIMP is a powerful software package for photo editing and is a great tool to install on your Raspberry Pi. STEP 1 Open terminal and enter: sudo apt install gimp to download and install the GIMP package. An alert will appear saying: “after this operation, 117 MB of additional disk space will be used. Do you want to continue [Y/n]?” Enter: y and press Return. GIMP will now be installed in Raspberry Pi OS. GIMP is a lot larger than most programs you’ll install, so the installation takes STEP 2 When the installation has completed you will find GIMP under Menu >…

IT’S ALL MATHS, MAN You can get some really impressive results with the mathematical powers of Python; as with most, if not all, programming languages, maths is the driving force behind the code. STEP 1 Open up the GUI version of Python 3, as mentioned you can use either the Shell or the Editor. For the time being, you’re going to use the Shell just to warm our maths muscle, which we believe is a small gland located at the back of the brain (or not). STEP 2 In the Shell enter the following: You can see that Python can handle some quite large numbers. STEP 3 You can use all the usual mathematical operations: divide, multiply, brackets and so on. Practise with a few, for example: STEP 4 You’ve…

MASTERING MODULES Think of modules as an extension that’s imported into your Python code to enhance and extend its capabilities. There are countless modules available and as we’ve seen, you can even make your own. STEP 1 Although good, the built-in functions within Python are limited. The use of modules, however, allows us to make more sophisticated programs. As you are aware, modules are Python scripts that are imported, such as import math. STEP 2 Some modules, especially on the Raspberry Pi, are included by default, the Math module being a prime example. Sadly, other modules aren’t always available. A good example on non-Pi platforms is the Pygame module, which contains many functions to help create games. Try: import pygame. STEP 3 The result is an error in the IDLE…

CREATING FILES Once you learn to recognise the files and directories that make up Raspberry Pi OS OS, it’s time to discover how to make your own. Knowing how to make, edit and delete files and directories is essential if you want to make your own projects. STEP 1 We’re going to create a file using a command called Touch. Touch is an interesting command that reaches out to a file, or directory, and updates it (this changes the system time as if you’d just opened the file). You can see Touch in access using “ls –l” and checking the time next to a directory (such as Scratch). STEP 2 Now enter: touch Scratch and ls –l again and notice that the time has changed. It now matches the current…

HEY, MAN! The man pages are one of the best features of Linux, and as a built-in tool it’s invaluable for both beginner and senior level Linux administrators. Let’s see how it works STEP 1 Linux has a built-in manual, known as man for short. Using the man command you can obtain information on all the Linux commands we’ve talked about. Simply enter: man and the name of the command you want to learn more about. Start by entering: man ls in the command line. STEP 2 The man pages are a bit more detailed than you might be used to. First you have a name, which tells you what the command is called; in this case “list directory contents” and then the synopsis shows you how it works. In…

OWNER AND PRIVILEGE Each user account in Linux is an owner of a section of the filesystem: their Home area. Within this area, they do what they like (within reason), as they have owner privileges. Elsewhere though, they usually just have read-only privileges. STEP 1 If you followed the previous tutorial you should now have two accounts on your Raspberry Pi. One called “pi” and the other with a name (Lucy in our case). An essential aspect of Linux is the idea of file and directory ownership; who owns, and has access, to what. You need a test file so enter: touch testfile. STEP 2 Now enter: ls –l and let’s have a good look at the default permissions file. Our testfile.txt files starts with the text “-rw-r--r—“. Start with…

IN, OUT, LINUX ALL ABOUT Everything on a computer is about input and output. You input things into the computer (press keys, move the mouse) and it makes calculations and outputs content (changes the display, makes a noise, for example). STEP 1 When you enter commands into Linux (in the command line), you are using standard input and output. This is so obvious that most people don’t even think about it. You enter commands using the keyboard (that’s input) and it responds to the screen (output). This is the regular way of doing it, which is why it’s “standard input and output” (often called “stdin” and “stdout” for short). STEP 2 As far as the computer is concerned, input and output can be to and from a whole range of…

THE GOLDEN ERA OF CODE While it may seem a little counterproductive to learn how to code in a language that’s virtually obsolete, there are some surprising benefits to getting your hands dirty with a bit of retro coding. Firstly, learning old code will help you build the structure of code as, regardless of whether it is a language that was developed yesterday, or forty years ago, code still demands strict discipline to work correctly. Secondly, everyday coding elements, such as loops, sub routines and so on, are a great visual aid to learn in older code, especially BASIC. Lastly, it’s simply good fun. GOING BASIC The easiest retro language to play around with is, without doubt, BASIC. Developed back in the mid-sixties, BASIC (Beginner’s All-Purpose Symbolic Instruction Code) is…

TROUBLESHOOTING YOUR RPI The Raspberry Pi is a surprisingly stable bit of kit, but there is always the chance of encountering problems. If you’re really stuck there are apps available which can help diagnose problems on the RPi. RED POWER LED IS BLINKING A blinking red power LED indicates problems with the power supply. On model A and B, it is hard-wired to the 3.3V power supply rail. If it is blinking, it means the 5V power supply is dropping out. Use a different power supply. On the model B+ and also the A+, the circuit has been improved to give a much more reliable warning of poor power quality. The red power LED is wired to an APX803 supervisor which kicks in when the 5V power supply drops below…