Table of contents for Volume 2 Revised in Raspberry Pi Tips, Tricks & Hacks

System administration Get the most out of Python in handling all of the day-to-day upkeep that keeps your system healthy System administration tasks are some of the most annoying things that you need to deal with when you have to maintain your own system. Because of this, system administrators have constantly been trying to find ways to automate these types of tasks to maximise their time. They started with basic shell scripts, and then moved on to various scripting languages. For a long time, Perl had been the language of choice for developing these types of maintenance tools. However, Python is now growing in popularity as the language to use. It has reached the point where most Linux distributions have a Python interpreter included in order to run system scripts,…

While you’re settling down to enjoy your latest boxset, there’s always that nagging feeling at the back of your mind – is the baby asleep, or crying down the house? Surround sound tends to get in the way, which means we need to rely on baby monitors. While audio monitors are useful, the trend these days is more towards video baby monitors, in particular those that display footage on an app or by opening an IP address in a mobile browser. Throw in some motion detection and alert software, and you’ve got an incredibly useful tool – which, you won’t be surprised to learn, the Raspberry Pi can do for a fraction of the cost. All you’ll need is a Raspberry Pi (the newer the better), and a USB webcam…

You will probably have played Rock, Paper, Scissors in real life. The issue with this version is that there are only three possible outcomes other than a tie. Sam Kass and Karen Bryla invented an alternative version which adds “Spock” and “lizard”. “Spock” is signified with the Star Trek Vulcan hand sign, while “lizard” is shown by forming the hand into a mouth. Spock smashes scissors and vaporises rock; he is poisoned by lizard and is disproved by paper. Lizard poisons Spock and eats paper; it is crushed by rock and decapitated by scissors. This tutorial walks you through creating your own SenseHAT version of the game. 01 How RPSLS works with the Sense HAT When you complete this tutorial you will have a folder which contains five 8 x…

Wearable tech is an ever-growing industry, bursting with smart watches, fitness gadgets and pulse-rate necklaces. For many, this technology is nothing new; enthusiasts have long created their own wearable versions. Clothes that light up on contact, masks that change voices and weapons that glow! In this tutorial you will use your old Christmas LED lights, Python and the Pi Zero to modify a hat that lights up when you receive a specific tweet from your timeline. The Pi Zero is the perfect size and can be embedded into the clothing. You can customise the project for your own wearable tech, perhaps shoes that light up or a pair of gloves or a jumper that responds to the weather. 01 Sign up for Twitter API keys To interact with Twitter, you…

You may remember or have even played the classic Minesweeper P C g ame t hat o riginally d ates b ack t o t he 60s. Over the years it has been bundled with most operating systems, appeared on mobile phones, and even featured as a mini-game variation on Super Mario Bros. This project will walk you through how to create a simple version in Minecraft: it’s Minecraft Minesweeper! You will code a program that sets out an arena of blocks and turns one of these blocks into a mine. To play the game, guide your player around the board. Each time you stand on a block you turn it to gold and collect points, but watch out for the mine as it will end the game and cover…

So you have a Raspberry Pi and have now mastered the basics of setting it up, accessing the Desktop, getting online and loading the various pre-installed software. This tutorial is packed full of 50 skills, codes and hacks to try on your Pi, which span two pieces of software and one additional piece of hardware. First up is the Raspberry Pi SenseHAT which was initially sent to the ISS station to run code and experiments. This addon board will cost you around £26.50 ($57.99 from Amazon in the US) and provides a wide array of sensors, including a temperature sensor and an LED matrix. Get to grips with the essential code in order to program it and then you can create your very own real time humidity sensor and display.…

You can use a Raspberry Pi and an Energenie IR board to make a brilliant remote and control your TV, but you can do so much more. Welcome to the world of the IR board, where almost anything is possible. We’ll use it to record signals from a remote control robotic toy and combine these with pygame commands to enable you to control your robot from your Raspberry Pi. Since the code is Pythonbased, you can then develop it further, use social media to control the robot with tweets, or install Flask to create a web interface accessible from your mobile phone. 01 Update the boot file Before booting up your Raspberry Pi, attach the Energenie IR board to GPIO pins. The board slots onto the top of the pins,…

Docker is a framework and toolchain used to configure, build and deploy containers on Linux. Containers provide a means to package up an application and all its dependencies into a single unit. This makes them easy to share and ship anywhere, giving a lightweight and repeatable environment. Each application runs in its own isolated space sharing the host’s kernel and resources, in contrast to a virtual machine which needs to ship with a full operating system. A Docker container can be started or stopped within a second, and can scale to large numbers while having minimum overhead on the host’s resources. The Docker community has built out a clustering solution called Swarm which, as of version 1.0, is claimed to be “production ready”. Our single Raspberry Pi has 1GB RAM…

What are the big changes? A lot of the Raspberry Pi 3 is the same as the Raspberry Pi 2. Our strategy for the Pis from the B+ has been to try and keep the same form factor. The B+ was really the first Pi that I worked on when I came to Raspberry Pi in 2013, and the idea was that we’ve got this nice form factor and we want to keep it, so to build the Pi 3 I took the Pi 2 design and literally just added the extra stuff. So, we’ve got the new processor courtesy of Broadcom – they’ve done a nice uplift. It’s similar to the BCM2836; the Cortex A7 was taken out and the A53s were put in, and everything else has actually…

Get started with BASIC Whether you remember BBC BASIC or it’s completely new to you, you’ll have it at your fingertips in RISC OS. To open a command line, click Ctrl+F12, then type BASIC and enter. You are then ready to enter a basic program: Esc will stop this routine. Dedicated programming editors are available for BBC BASIC, although you can develop code with WIMP and C too. You’re happy using Raspbian to get the most from your Raspberry Pi. You might have flirted with the idea of Ubuntu or Arch Linux, but never seen the point. After all, when it comes to maximising what you can do with the Pi, the official distro has everything you need, right? But, what about trying a non-Linux operating system? The Cambridge-developed RISC…

The Sensly is a smart module attached to the Raspberry Pi. It has its own microprocessor that can handle analog data and handle sampling from various sensors without the need to waste your Raspberry Pi’s processing power. There are three different gas sensors attached to the board, allowing you to sense a multitude of gases, as well as humidity and temperature sensors. Plus, this Raspberry Pi HAT can be easily extended with its array of analog ports and an I2C interface. In keeping with the Raspberry Pi way of doing things, the module also provides a Python API that does all of the hard work for you. All of the maths, calibration and error correction is handled by the API itself, allowing you to play around with meaningful data immediately.…

The folks at Energenie have created some genius plug sockets that can be turned on and off via your Raspberry Pi. You can buy a starter kit which includes the RF transmitter add-on board and two sockets to get you started. The add-on board connects directly to the GPIO pins and is controlled with a Python library. Once everything is installed and set up, your Raspberry Pi can be used with the Pi-mote to control up to four Energenie sockets using a simple program. This tutorial covers how to set up the software, the sockets and how to adapt the program to run on your mobile device. 01 Set up To get started, boot up your Raspberry Pi and load the LX Terminal, then update your software by typing: Depending…

Are you concerned about your online privacy? Suspect that the NSA or GCHQ are tracking you online? Or are you simply anxious about advertising networks targeting their ads at you? If this is the case, or you’re simply on the lookout for a new project, then setting your Raspberry Pi up as an anonymisings Tor wireless access point is a good way to save time and effort setting up Tor on all of your PCs and mobile devices. If you’re unaware, Tor is free software that enables anonymity online and routes internet traffic through a worldwide anonymising network of over 7000 relays. By doing this, your location and website use can be concealed from techniques such as traffic analysis and network surveillance. This is all about protecting your privacy by…

01 Update your Pi Before you start a project or hack, ensure your Pi software and operating system are up to date. Open the LX terminal, type: 02 Installing and deleting software When online your Raspberry Pi can access a wide range of software and programs. Many of these are stored in a publicly maintained repository. If you know the name of the software you require, for example, the chrome browser, then type: To delete unwanted software use: To find search for software with a keyword use: 03 Display your IP address To find your IP address, use a simple script to print it to the console window. This happens just after boot up, before your login credentials are entered. Open the LX terminal and type: Add the following script…

38 Blocks have ID numbers Within the Minecraft environment each block has a name and an ID number which is used for reference. You can retrieve the block ID using mc.getBlock(p.x,p.y-1,p.z) which returns the block type you are stood on. This is useful for working out where you are in the world and how close to other elements you are. You can then code the player to respond for example, if they are stood on grass it trampolines them into the air: 39 Know where your player is When playing Minecraft your player inhabits a three dimensional environment. The ‘x’ axis, left and right, the ‘y’ axis up and down and the ‘z’ axis for forward and backwards. As you move along any these your position is displayed at the…

Camera The camera module is the focal point for object detection. Input data is collated then put through a client program running on the Pi. Ultrasonic sensor This senses angles and surface conditions to determine the stopping distance relative to an oncoming object. Arduino This simulates the button presses of the RC car controller. Four pins connect to pins on the controller, for forward, reverse, left and right. Components list ■ Raspberry Pi B+ ■ Arduino ■ Camera module ■ HC-SR04 ultrasonic sensor ■ OpenCV Where did the idea to develop a selfdriving car come from? Believe it or not, I actually did this for a school project. A lot of my interests centre around machine learning, so I decided to do something that heavily involves machine learning and the…

So you’ve picked up one of the tiny yet powerful Zeros, but before the coding fun can begin, you need to get more familiar with it. Don’t worry; we’ll walk you through the Raspberry Pi Zero, the required cables, how to prepare a NOOBS SD card, and how to solder the GPIO header onto the Pi. Once the Pi is working and booted we’ll show you how to get it working on WiFithrough the Raspbian user interface. You’ll need a USB hub for this, or even just to use a keyboard and mouse together. We’ll also show you how to prepare a Raspbian SD card for headless use (either VNC or SSH) with only a WiFi adapter or USBtoEthernet adaptor. 01 Raspberry Pi Zero Cable Overview The Raspberry Pi Zero…

Why Python? It’s the official language of the Raspberry Pi. Read the docs at python,org/doc. The majority of programmers will learn single-threaded programming as their first computational model. The basic idea is that instructions for the computer are processed sequentially, one after the other. This works well enough in most situations, but you will reach a point where you need to start multitasking. The classical situation for writing multithreaded applications is to have them run on a multi-processor machine of some persuasion. In these cases, you would have some heavy, compute-bound process running on each processor. Since your Raspberry Pi is not a huge 16-core desktop machine, you might be under the assumption that you can’t take advantage of using multiple threads of execution. This isn’t true, though. There are…

We program Minecraft to react in python using the API that comes with Minecraft: Pi Edition – it’s what we moved to the home folder earlier on. Now’s a good time to test it – we can do this remotely via SSH. Just cd into the Minecraft folder in the home directory we made, and use nano test.py to create our test file. Add the following: “Hello, Minecraft!” should pop up on-screen. The code imports the Minecraft function from the files we moved earlier, which allows us to actually use Python to interact with Minecraft, along with the various other functions and modules imported. We then create the mc instance that will allow us to actually post to Minecraft using the postToChat function. There are many ways you can interact…

Finding the content you’re interested in viewing can take a while. W hether y ou’re l ooking f or i nternet T V s tations, video podcasts, audio podcasts or shows syndicated online, taking the time to find and download them can be slow going, particularly if you have a busy lifestyle. You might even have no time to watch after you’ve waited for the download. Thanks to the Miro media management software, we can automate all of this, and with the software running on a Raspberry Pi, you can easily build a compact system for downloading and playing back shows that you have an interest in. We’re talking targeted TV on demand, which makes this project ideal for staying up to date with particular news and trends on a…

There is a Python library for Logitech Media Server (https://github.com/jinglemansweep/PyLMS), which allows you to automate various tasks. Check out the code below to write an application that pings your phone and pauses the players once your phone drops off the wireless network (indicating that you’ve left the house). Once you return, the application can press play. Start your script It makes the most sense to set your script up on the server: Finally, make the script start at boot: Then enable the service and reboot to test it: Cost of implementation Assuming you already have an old Pi or two lying around, this can be a fairly cheap project – there are plenty of good quality class T speaker amps around that you can get for £20 or so. Just…

06 Countdown has begun Display a simple countdown from 10 to 0 on the LED matrix. Convert the number values to a string to show them on the Matrix. Open Python 3 and add the following code: 07 Enable max current draw If you have a good power supply (ie 2 amps or more) and want to connect a current-heavy device, add the line max_usb_current=1 to /boot/config.txt, to set the max current over USB to 1.2 amps instead of the default 600mA. 08 Scroll text Open your Python editor and enter the code, save and then run it to scroll your message across the SenseHAT LEDs. Adjust the colour of the message and the time it takes to scroll by including the lines, text_colour=[255, 0, 0]) (setting the RGB value)…

In a previous article, we looked at how you can capture images using a camera and a Raspberry Pi. This let you include image capture functionality within your own Python program, but there is so much more you can do once you add vision to your code. This month, we will look at how you can add motion detection to your Python program. This kind of advanced image processing is extremely difficult to do, so we will definitely be building on the hard work of others. Specifically, we will be using the excellent OpenCV Python package. This package is constantly being improved, with more functionality being added with every update. The first thing you will need to do is install the various Python packages that you will need to talk…