Table of contents for Vol 3 in Raspberry Pi Annual

While playing audio and presenting images is all well and good, sometimes a video is the clearest way to display output. Luckily, pygame can help you with this, too. There is a movie object available that can handle the playback of MPEG-1 video files. The constructor takes a filename for the movie file: pygame.movie. Movie(filename). You can check the data and see whether there is video data or audio data with the helper functions has_audio() and has_video(). Movie objects do need to be displayed on some kind of surface. The default surface that the movie object will use is the display surface. If this isn’t to your liking, you can change this to a different surface with the method set_display(). This draws over everything on the surface, so you may…

Since the Raspberry Pi is such a small computer, it gets used in a lot of projects where you want to monitor a source of data. One such monitor you might want to create is a mail-checker that can display your current unread emails. This issue, we’ll look at how to use Python to create your own mail-checking monitor to run on your Pi. We’ll focus on the communications between the Pi and the mail server and not worry too much about how it might be displayed. That will then be left as a further exercise. To start with, most email servers use one of two different communication protocols. The older, simpler one was called POP (Post Office Protocol), and the newer one is called IMAP (Internet Message Access Protocol).…

“But, what about 3D?” we hear you ask. Luckily, we can reuse much of what we have already covered here to move into three dimensions. The first change is that vertices now are defined with three values rather than two, giving you a set of x, y and z coordinates. The second change is in the category of functions that you need to use. You can see that the drawing functions used are explicitly two-dimensional in their names. For example, you should have noticed the ‘2’ in names like ‘glVertex2f()’. To draw three-dimensionally, this changes to names like ‘glVertex3fv()’. The third change is more conceptual. Once we move to three dimensions, we need to worry about where we are in relation to the object that is being drawn, and what…

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 multi-threaded 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 lots of problems that map naturally to the multiple thread model. You may also have…

Pimoroni has created the PianoHAT, the ultimate mini musical companion for your Raspberry Pi! It is inspired by Zachary Igielman’s PiPiano and made with his blessing. The HAT consists of a dinky eightkey piano add-on, with touch-sensitive keys and LEDs. It can be used for many creative and musical purposes, such as playing music in Python, controlling software synths on your Raspberry Pi, taking control of hardware synthesisers, or unlocking your inner Mozart. This tutorial will show you how to set up the hardware, introduce you to the basic features of the software and show you how to combine these together in Minecraft to c reate musical b locks and a visualisation of your melodies. You can view a demonstration video here: https://www.youtube.com/watch?v=ezJgXp01MPk 01 Getting started Pimoroni has made it…

While the main part of the article is about querying Google Calendar to pull event details to populate a family calendar display, there is nothing stopping you from working in the other direction and updating the remote calendar based on what happens at the monitor. This way, you can keep yourself synchronised with what is happening back home. The first thing you might want to be able to do is to add a new event to a calendar. While there is an 'insert' method, it is probably overkill for such a simple application. For your family calendar, you probably just want to use the 'quickAdd' method. Let's say that you need to actually update an existing event. As an example let's say you got the time wrong on the above…

In the main article, we have been using the Raspberry Pi module that plugs into the IO bus of the Pi. But what if you don’t have easy access to one of these? Almost everyone has an old webcam sitting around the house somewhere, and the Raspberry Pi has a perfectly useful USB port. The image quality and frame per second count is not as good as what you can get with the actual Pi Module. The key is getting the image data off the camera in the format that the OpenCV image analysis functions is expecting. The VideoCapture() function can not only take a video file name to read in, but can also take device IDs for cameras attached to the Raspberry Pi. Assuming that you only have one…

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’re 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. What you’ll need ■ RISC OS http://bit.ly/2auOpYL ■ Monitor ■ Keyboard ■ Three buttoned mouse (a standard clickable scrollwheel should suffice) 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…

Cory Guynn is an IoT and cloud computing enthusiast, and a veteran Cisco Meraki systems engineer specialising in international deployments. To better understand IoT use cases, he has replicated them with LEGO and electronics Like it? Cory is documenting the entire build process over at internetoflego.com, and is also uploading the scripts for his smart city. From the city lighting and train automation through to the PubNub hub setup, it’s all there for you to explore Further reading SAM Labs launched an electronics kit earlier this summer that essentially combines LEGO and IoT: there are 15 individual blocks, each wireless and with a different sensor, slider or button, that can be snapped together: samlabs.me How long have you been working on this project? I would say since September, when I…

In the previous issue (158) we looked at how to create a hack to control your TV using the Energenie Pi-Mote IR board and a Raspberry Pi. We return to the world of the IR board, only this time we 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, the…

The whole point of using a Raspberry Pi and building your own environmental monitor is to have something that can operate independently and away from any available amenities. This is fine if you are only interested in recording and storing the data that you are collecting to look at it later in an offline fashion. But what if you want to check in on your monitor and see what it is actually measuring? In this case, you should be able to connect some type of USB device that allows it to connect to the internet. This could be as simple as a Wi-Fidongle, if you have a Wi-Finetwork nearby, or something that operates over the cellular networks for more remote access. Once you have your Raspberry Pi connected to the…

While the GPS receiver connected to your Raspberry Pi can give you your exact coordinates, most people cannot process latitudes and longitudes in any intuitive way. Luckily, there are several services available on the internet, called geolocation services, that can help translate these coordinates to another form that is more intuitive. You will need to install the relevant Python module on Raspbian, with the command The core part of the geopy module is the concept of a geocoder. There are prebuilt subclasses for services like Google, Yahoo and Bing. You can use whichever is your favourite one. In the following examples, we will use the Nominatim geocoder for the OpenStreetMap geolocation service. To start with, you can create a geocoder with Normally, most people use this to find the coordinates…

Whether you’ve just gotten your lucky hands on a powerful, petite new Raspberry Pi Zero or you’re looking to maximise the efficiency of the faithful Raspberry Pi you already own, this is everything you need to get started on boosting not only your Raspberry Pi but your own knowledge. The Raspberry Pi is a versatile little piece of hardware, with a wonderfully creative amount of potential, and though most of you will be familiar with its more day-to-day functions, there are always tweaks and adjustments to be explored that can tailor the Raspberry Pi to your own desired user experience. From soldering to useful Python features, GPIO interrupts to remote access, and a whole lot more, this masterclass in technical and practical skills covers fifty useful ways to get…

In the main body of the article, we have only looked at how to connect to an email server and how to read from it. But what if you need to be able to also send emails off using some code? Similar to poplib and imaplib, the Python standard library includes a module called smtplib. Again, similar to poplib and imaplib, you need to create an SMTP object for the connection, and then log in to the server. If you are using the GMail SMTP server, you could use the code This code asks the end user for their password, but if you aren't concerned about security, you could have it hard-coded into the code. Also, you only need to use the login() method for those servers that require it.…

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…

Love Hultén’s passion for retro gaming, stunning design and the Raspberry Pi has culminated in some of the most breathtaking handheld consoles in recent times. Like it? If you’re on the lookout for a slightly bigger console that still uses the Raspberry Pi as its core computer, make sure to check out Hultén’s numerous other projects. You can find all the relevant details and availability information over on his site at www.lovehulten.com Further reading Emulation on the Raspberry Pi is easier than you might think. For those interested, make sure you read up on the likes of the heavily used RetroPie, or RetroArch, which arguably produces a crisper gameplay experience. As ever, make sure you own original copies of each game you download to avoid the potential piracy issues. So…

What if you need to actually have truly parallel code, that has the ability to run on multiple cores? Because Python has the GIL, you need to move away from using threads and go to using separate processes to handle the different tasks. Luckily, Python includes a multiprocessing module that provides the process equivalent to the threading module. As with the threading module, you create a new process object and hand in a target function to be run. You then need to call the start() method to get it running. With threads, sharing data is trivial because memory is global and everybody can see everything. However, different processes are in different memory scopes. In order to share data, we need to explicitly set up some form of communications. You can…

Jessica Mabin is a PhD student in Physics and Astronomy at Cardiff University. She has been looking at different ways to use science to help solve global issues. Like it? Despite the advanced nature of the project, Jessica and the rest of the team have made some amazing progress. So much so that a timelapse video of the project has been uploaded to show off some of its key features. Take a look here: http://bit.ly/2aMQx8B Further reading This project shines light on a global issue, so we take our hats off to the team at Cardiff Uni for taking this on. For those interested, the official Raspberry Pi blog has a great run through on the basics behind the science of the project for all to enjoy: http://bit.ly/2biU5ST Could you…

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…

” In a previous piece, we looked at how you could use your Raspberry Pi and some Python code to look at a scene and figure out whether there was any motion there. This month, we will take it one step further and see if we can get our Raspberry Pis to actually recognise faces. We’ll assume here that you are either using the camera module for the Raspberry Pi, or a USB web cam. In either case, you have a stream of images being handed to your code, ready to be processed. Again, as in previous articles, we will be using the OpenCV Python module to handle all of the heavy image processing involved. The first step is to be sure you have Python and the OpenCV module installed…

The Raspberry Pi was designed to provide several ways to interact with the world through sensors and activators. In the past, we have looked at using the GPIO interface pins to communicate with several devices at once. This is not the only way to work with the world at large, however. This month, we will look at one of the other mechanisms available, the I2C bus. I2C (Inter-Integrated Circuit) bus was invented by Philips Semiconductor, with version 1 having come out in 1992. The design is for short connection paths, and supports multiple masters and multiple slaves where messages on the bus are delivered using device addresses. Messages have a START section and a STOP section, wrapped around the core of the message. The three types of messages that you…

Most of the time when you install an application in Linux, you do so via a package manager, which enables the download and installation of binary packages, built from source packages. These include the default options, general features and parameters so that a wide portion of users can install without any problems. However, if you’re developing code, you first need to create a source package, and on a Raspberry Pi this can seem to take forever. One option is to copy the code to a desktop or notebook computer running Linux, but wouldn’t it be far more convenient to just let the Raspberry Pi deal with it… but give it a helping hand? Using distcc, we can distribute the resources needed to build the package, which basically means we can…

Back in issue 155, we looked at how to call C functions from within a Python program to get more speed. But, there are times, within a C program, when you may want to execute some piece of Python code. Maybe you want to be able to run user code within your program, for example. This means you can enable users to use plug-ins to extend your program’s functionality. The way we can do this is by embedding Python within the C program. We will look at how to embed, how to run your Python code, and how to interact with the Python interpreter you’ve set up. This is functionality built into Python itself, so you don’t need to install anything extra on your Raspberry Pi, aside from the development…

Frederick Vandenbosch is an integration engineer by day and builder of electronic things by night. He likes to build things as a way of learning about a subject and have fun while doing so. Not all builds are successful, but that’s part of the learning process! Like it? If you’d like to see more of Frederick’s work, check out his website: bit.ly/1XC8uu9. The rest of the Sci FiYour Pi entries, including an actual Tricorder, can be found here: bit.ly/1kekbsc. Further reading Thinking of putting your own Tron desk together? There’s a great woodworking video here from Bob Clagett at Make that shows you how to craft a coffee table with embedded LED strips, which is a great starting point: bit.ly/1WlhVeI. Tell us a bit about the competition that you entered…

Michael Horne is a ColdFusion/SQL web developer residing in the UK. As well as being a Raspberry Pi enthusiast, he’s also an avid part of his local amateur theatre group. Like it? Standalone music players that make use of the Pi’s great features are available from several outlets. If you want your Pi to act as a hub for streaming your favourite tunes through, check out pimusicbox.com. Further reading Michael has been kind enough to upload detailed instructions on his music box build over on his site: www.recantha.co.uk. Make sure to check out his numerous other projects also listed on his site, you are bound to be inspired! Where did the idea for the music box come from? I’ve always had an interest in music. I perform in amateur musicals…

Niels Affourtit is an avid scuba diver who has turned his love for all things nautical into constructing an underwater ROV. Like it? Niels has uploaded a series of YouTube videos depicting the original testing of the ROV, as well as how it performed in open water conditions. Check out his channel: youtube.com/user/gravitylost1 Further reading Niels took a lot of inspiration from the OpenROV team, who have been producing underwater exploration vehicles for a number of years. Take a closer look at what they do over at www.openrov.com Why did you decide to build an ROV (remotely operated vehicle)? When I was a kid I frequently built RC models; sailing boats and speedboats. While I owned a fantastic RC glider and dreamed of having my own RC submarine someday, my…

Frederick Vandenbosch is an integration engineer by day and builder of electronic things by night. He likes to build things as a way of learning about a subject and have fun while doing so. Like it? While nowhere as cool as Frederick’s project here, the Pi Hut has its own Raspberry Pi-based controller worth checking out. It works as the perfect companion for your FLIRC module, or perhaps even for improved XBMC/Kodi control. Further reading For those interested in recreating this gesture TV remote control, Frederick has uploaded a full tutorial on his website: frederickvanden bosch.be. On his site, you’ll also be able to take a look at his other Pi projects, including an IoT light, Amazon Echo controller and a panic button. Wood does not affect the gesture detection…

David Pride has been working on various Raspberry Pi projects for a number of years, with many of his creations showcased across the UK. Like it? Puzzle-solving Pi robots are always well received, and if you like the look of David’s Connect 4 robot, go ahead and check out this Rubix cube solving robot from Maxim Tsoy. It’ll be a while before it can beat the world record, but it isn’t far off: http://bit.ly/1SvrIQ6 Further reading A large part of the development of the Connect 4 robot stems from the Minimax algorithm. It’s fairly complex, but adaptable to a wide number of projects and useful when mixing motors and servos with the Raspberry Pi. A complete guide to the algorithm can be found here: http://neverstopbuilding.com/minimax The trickiest part was capturing…

Perhaps you can easily churn out code to run on your Raspberry Pi but, sooner or later, you’ll probably have a hankering to interface it to LEDs, sensors and other realworld devices. Sure you can easily attach a ready made board, perhaps a HAT, to the Pi’s GPIO connector, but if you want to go further your C++ or Python programming skills aren’t going to help. The web is awash with circuits for the Pi, ranging from simple ones to light-up LEDs, through PIC programmers to ambitious home automation projects. But to turn these from a circuit diagram into a working circuit requires some electronic skills. Here we’ll teach you how to build an electronic circuit from a circuit diagram. In addition to helping you build circuits that others have…

Why Python? It’s the official language of the Raspberry Pi. Read the docs at python.org/doc There may be many times when you want to use multimedia within your interactions with an end user. You may want to display a really interesting bit of video or have your program chat audibly with the user. In both of these cases, there are lots of modules available to enable you to work all of these other forms of data. However, a truism about programming is to ‘find the easiest way to do something’. Here, this means if you can find a single framework that provides everything you need, you should probably use it. This is the role that the module pygame fills. This isn’t to say that you will be able to do…

What you’ll need ■ A Raspberry Pi for each room you would like to play music in (one of these can act as a server or a sever can be separate) ■ Ideally a USB sound card for each Pi (a Behringer UCA-202 is a great option) ■ Speaker amplifier and speakers to plug the Pi into ■ A wired or wireless network ■ A USB Wi-Fiadapter for each Pi you want to be wireless (an Edimax EW-7811UN works out of the box) In this article we are going to use Logitech’s Squeezebox Media Server and the squeezelite client to create a multiroom audio system. The media server can stream audio to each squeezelite client and also synchronise the playback between multiple clients if desired. Logitech open-sourced the Squeezebox software…

Many of the examples we have looked at in this column have been programs that run on the console. This month, we will be taking a look at how you can include 3D graphics within your Python code. The hardware on the board includes a GPU, so you should be able to take advantage of everything this computer is capable of. Since we are going to be playing with graphics, this means that you will probably want to have an actual monitor connected to your Raspberry Pi. If you don’t have one, you can connect to your Raspberry Pi over SSH with X11 forwarding turned on. As long as you have an X11 server on your desktop, you can see the display on your local machine. To get access to…

Evan Kahn is an engineering student at Harvey Mudd College interested in music, activism, and human-computer interaction. Find him at wormyrocks.github.io Kyle Lund is a robotics major at Harvey Mudd College, class of 2017. He’s from Boulder, Colorado, and spends his free time running, skiing and playing piano Like it? Interested in building your own Pixel Globe? Evan and Kyle use Adafruit’s DotStar LEDs: bit. ly/1RkdeEm. Their project code can all be found on their GitHub page: bit. ly/1P7ZEgL. As for the FPGA, check out the MuddPi Mark IV Board schematics at bit.ly/1KbABrY Further reading There are some great build notes for this project over at Hackaday: bit.ly/1Ogj9Xn What is the persistence of vision phenomenon? Evan Kahn: When something moves, your eye can’t immediately update the things that it sees,…

For many people today, a major issue is keeping their time organised and keeping track of scheduled events. This gets compounded exponentially for every additional person that you need to keep track of. That includes children. This issue, we will look at how you can use a Raspberry Pi to display a family calendar and help you keep track of all of the events happening in the lives of your family members. Like the previous articles in this series, we will be focusing on the code you will need to get your calendar information. As for the actual physical display, there are many options you could choose. These include small HDMI displays or small screens that plug directly into the GPIO pins. Your choice of display should be made based…

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…

We have seen that the key part of object detection within an image is the cascade file. When you open one up, you will notice that it doesn’t seem to be very complicated. The complicated bit is in the encoded data that defines that features within the cascade algorithm that are used to identify the object. This data needs to be discovered through a training step where the relevant OpenCV functions look at images that both have the object in question and images that do not have the object. You need a much larger set of negative images compared to positive images. For example, the author of the blog entry at http://coding-robin.de/2013/07/22/train-your-own-opencvhaar-classifier.html needed to use a set of 40 positive images and 600 negative images in order to identify bananas…

The Raspberry Pi has another communication bus available for you to use, called the SPI bus (Serial Peripheral Interface). It is similar to the I2C interface, except it only allows for a single master. The SPI bus is also not active by default.; you will need to activate it, either manually or by using the ‘raspi-config’ utility. You will also need to install the relevant python module with Once you have SPI activated and the spidev module installed, you can initialise the bus with the code The next step is to open a connection to the device of interest. To do this, you need to use the function The two parameters in the open function are the bus and device IDs for the device you want to talk to. When…

Welcome to part one of a special robotics series. We will equip you with everything you need to know to make your own Raspberry Pi robot. In this first part we break down a robot into all its component parts and give you an insider’s perspective on batteries, motors, input controllers and more. What exactly is a ‘robot’? A robot is considered to be any machine that can perform a task or series of tasks, either autonomously once programmed or with direct instruction. Robots come in many shapes and sizes – they can be used for manufacturing, for search and rescue, and for just having fun and seeing what you can create. The hobbyist creations we saw at Pi Wars recently were wheeled or tracked, disconnected from any wires, and…

With the Python interpreter, you aren’t just limited to what is already available; you can extend the available functionality by defining your own Python objects, with their own methods and data, within your C code. These newly-created objects can then be called from within the Python interpreter. They are defined as static objects, with code like: The new PyObject contains the executable code for the methods to be used for your new object. You also need to create a method definition to be able to register the details with the Python interpreter. You do this by creating a PyMethodDef array: Once you have finished these two parts, you are almost ready to start using your new module code. You need to initialise it with the function: Now, you can import…

With such a small physical footprint and a low power requirement, the Raspberry Pi is a perfect platform that you can use to build your own scientific equipment. We will look at how you might be able to use your Pi to monitor and analyse sounds in your environment. This is useful if you are listening for particular sounds. You need a Raspberry Pi, some kind of USB microphone, and some kind of USB wireless connection if you want to check on the monitoring process remotely. The specifics of the hardware are up to you, but you should be able to use almost anything that is available to you. This article will focus on the Python code that you will need in order to record this audio and do…

In previous articles, we have looked at how to add various types of sensors to the Raspberry Pi to get it to interact with the world around it. One very useful piece of information that your Raspberry Pi could collect is its location on the Earth. It may be very useful to know where you are in order to decide on what action to take. This issue, we will look at adding the functionality of GPS (Global Positioning System) to your Raspberry Pi and how to use it within your own Python code. For those of you who may not have run into GPS before, it is a constellation of 31 satellites orbiting the Earth. Using extremely accurate time systems and some very complicated maths, these satellites communicate with groundbased…

Zheng Wang has an academic background in electrical engineering and has put what he has learned into action with his Pi car project. Like it? Zheng has documented the entire process over on his blog at bit. ly/22Zh5uq. For those who want to replicate it for themselves, Zheng has also outlined the equations needed to get the object detection working correctly. Further reading David Singleton was where Zheng took his inspiration from, and we recommend you go check out his guide on how he built a neural network RC car at blog.davidsingleton.org/nnrccar. The process is a little different from Zheng’s, and it’s certainly an interesting read. Where did the idea to develop a selfdriving car come from? Believe it or not, I actually did this for a school project. A…

Tom Bennet by day is an SEO consultant based in London, but in his spare time he loves pushing the boundaries of the Raspberry Pi. Like it? Tom’s project is fairly unique, but it’s very much possible to build your own Raspberry Pi heating monitor. While the finished product doesn’t include the complexity of the terrarium controller, it certainly gets the job done. Head across to http://bit.ly/1g3AhR6 for the full tutorial. Further reading Tom has gone to the trouble of putting a detailed tutorial of the project on his blog over at www.bennet.org for anyone interested in building their own controller. You can also find all the necessary code available at his GitHub page: https://github.com/tombennet I chose the Pi 3 because I wanted the flexibility to add new components When…

The first step is to open a serial connection to the Arduino The Raspberry Pi is a truly amazing single-board computer that gets used in lots of DIY projects. That has been the basis for this whole column and the previous several articles. While the Raspberry Pi has a GPIO and can communicate with sensors and actuators, you may have cases where you want to use your Raspberry Pi as the brains of your project and offload the interactions with the physical world to another system. This is usually handled by one of the many microcontroller boards that are available. In this issue, we will specifically use the Arduino board and see how to connect it to a Raspberry Pi and how to handle the communications between the two. As…