ESSENTIALS EXPERIMENT WITH SENSE THE HAT SENSE THE REAL WORLD Raspberry Pi WITH YOUR Written by The Pi Education Team SUBSCRIBE TODAY & SAVE UP TO 25% Subscribe to the official Raspberry Pi magazine to make massive savings Subscription benefits Pricing Get it first (before stores) Quarterly from: Free delivery to your door £12.99/ $37.50 Never miss a single issue Six issues from: From £30/ $69 12 issues from: £55/ $129 How to subscribe: UK - ROW: +44 (0)1202 586848 US - 800 428 3003 Find us on your digital device by searching for ‘The MagPi’ Visit: magpi.cc/Subs1 WELCOME TO EXPERIMENT WITH THE SENSE HAT pace exploration is fascinating and S inspiring for children and adults alike. With the tiny Raspberry Pi computer helping to change the world little-by-little, it was only a matter of time before it went to space to help out there as well. This new adventure is called the Astro Pi project. To help the Raspberry Pi in its extraterrestrial mission, the Sense HAT was created to provide more functionality; the Sense HAT board sits on top of the Raspberry Pi, and has lights and sensors to allow the Pi to interact with the outside world. In this book, we aim to help you figure out exactly what the Sense HAT is and how you could use it to make your projects and dreams a reality. It’s an incredibly versatile and flexible bit of kit with plenty of very obvious uses, along with many many less-obvious ones, that you’ll love to make and share. Rob Zwetsloot Features Editor, Raspberry Pi FIND US ONLINE raspberrypi.org/magpi GET IN TOUCH [email protected] EDITORIAL DESIGN Managing Editor: Russell Barnes Critical Media: criticalmedia.co.uk [email protected] Head of Design: Dougal Matthews Features Editor: Rob Zwetsloot Designers: Lee Allen, Mike Kay Sub Editors: Laura Clay, Phil King, Lorna Lynch Illustrator: Sam Alder DISTRIBUTION SUBSCRIPTIONS Seymour Distribution Ltd Select Publisher Services Ltd 2 East Poultry Ave, PO Box 6337, Bournemouth London BH1 9EH | +44 (0)1202 586 848 EC1A 9PT | +44 (0)207 429 4000 magpi.cc/Subs1 In print, this product is made using paper This book is published by Raspberry Pi (Trading) Ltd., Mount Pleasant House, Cambridge, CB3 sourced from sustainable forests and 0RN. The publisher, editor and contributors accept no responsibility in respect of any omissions or the printer operates an environmental errors relating to goods, products or services referred to. Except where otherwise noted, content 3 [ mCahnaapgetemre nOtn seys t]em which has been in this product is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 assessed as conforming to ISO 14001. Unported (CC BY-NC-SA 3.0). [ EXPERIMENT WITH THE SENSE HAT ] ESSENTIALS CONTENTS [ THE PI EDUCATION TEAM ] 05 [ CHAPTER ONE ] WHAT IS THE SENSE HAT? Learn why you should be excited. 09 [ CHAPTER TWO ] HIGH FLIERS The Astro Pi mission in full. 21 [ CHAPTER THREE ] Some of the articles you’re GETTING STARTED WITH about to read were THE SENSE HAT created by the Learn how to use your new Sense HAT fantastic Raspberry Pi education team, a selection 34 [ CHAPTER FOUR ] of excellent GRAVITY SIMULATOR individuals who Cats on the moon need gravity too love to teach teachers how to use the Raspberry 39 [ CHAPTER FIVE ] Pi. As well as MAKE A DIGITAL seeing their work MAGIC 8 BALL at Picademies Shake up your fortune around the world, they also write teaching materials 44 [ CHAPTER SIX ] which can be INTERACTIVE PIXEL PET found online and A digital pet all of your own in The MagPi magazine. You can read many more 53 [ CHAPTER SEVEN ] of their tutorials ASTRONAUT REACTIONS GAME and lessons on the Are you as fast as a trained astronaut? Resources section of the Raspberry 57 [ CHAPTER EIGHT ] Pi website: raspberrypi.org/ SENSE HAT DATA LOGGER resources Keep a record of your surroundings [ D[o Cno’tn Pteanntisc ]] 44 ESSENTIALS ESSENTIALS ONE [ CHAPTER ] WHAT IS THE SENSE HAT? The special add-on to the Raspberry Pi that lets it interact more with the world around, as seen on the ISS! 55 [[ CChhaapptteerr OOnnee ]] [ EXPERIMENT WITH THE SENSE HAT ] he Raspberry Pi can do a lot of things thanks to its size, T portability, and ability to connect to the internet easily. With the GPIO ports you can control electronics and interact with the world. One of the best ways of doing this is by using an add-on like the Sense HAT. The Sense HAT is a very sophisticated add-on board for the Raspberry Pi. While HAT is an acronym (Hardware Attached on-Top), it does act in a way like a hat for your Raspberry Pi. The Sense HAT contains a suite of sensors that allows the Raspberry Pi to sense the world around it, along with an array of LEDs on top which can be used to display information on what the board can sense, and a little joystick. The Sense HAT is a vital component of the Astro Pi, the specially adapted educational Raspberry Pis which were sent up to the International Space Station with British ESA astronaut Tim Peake to run code created by children.This wasn’t what the HAT was originally designed for, though, as the Sense HAT’s Project Lead Jonathan Bell explains: “I sort of hijacked a pet project of James [Adams’s] and turned it into a space-faring board,” says Jonathan. James Adams is the Director of Hardware at Raspberry Pi, and along with Jonathan, was one of the main driving forces behind the Sense HAT. [ What is the Sense HAT? ] 66 ESSENTIALS “Effectively we wanted to produce a board that would be a neat, fun example of how to design a HAT” Jonathan continued. “It was an exercise in how to design a HAT which could be put into mass-production: how would somebody go about doing that so hundreds of thousands of HATs could be made, and how would we design the board to deal with that.” Half-way through development, what was once a relatively basic HAT had some sensors added to it, similar to the kind used on mobile phones. “Eventually we said, hang on a minute, what happens if we put loads of sensors on this thing and turn it into a kind of a cool toy!” When the Sense HAT was Above British eventually completed, it had three key sensors: separate pressure ESA astronaut and humidity sensors that can also both measure temperature, and Tim Peake, who will be using the a motion sensor that contained an accelerometer, a gyroscope, and a Sense HAT on the magnetometer. As mentioned before, these sensors are joined by the 8 ISS for various experiments x 8 LED screen and the joystick. created by Each sensor, the LED screen, and the joystick can all work school children independently of each other as well as all together at once. You could simply have the LED screen display little images for you, or have the Sense HAT keep track of the temperature throughout the day; it’s very flexible to use! All of this is accessible on the Raspberry Pi by just popping the Sense HAT on top of the the GPIO pins and using the right Python code, which is what the space-bound Astro Pis on the ISS are doing. “The Astro Pi experiments make good use of the HAT itself,” Jonathan told us. “Some of them in quite unusual ways. We have a few Easter eggs up there, which you’ll have to find out about, but there have been some ingenious uses of the sensors. One of the experiments that caught our 77 [[ CChhaapptteerr OOnnee ]] [ E[ XEXPPERERIMIMENENT TW WITIHTH T HTHE ES SENENSSE EH HAAT T] ] eye in terms of sensing was one that attempted to detect an astronaut. The astronaut detector sits there, monitoring the humidity, and if there is a certain percentage change in humidity in the module it thinks there’s an astronaut present. It flashes a message on the LED matrix saying “Are you there?”. The Astro Pis also have a special metal case which allows them (after a few other tweaks to the Raspberry Pi) to be spaceworthy, and we’ll talk much more about that in the section about the Astro Pi. A whole host of experiments designed by British school children went up with the Pi for Tim Peake to use, and the data from those experiments which make use of the Sense HAT will be sent down to Earth. The Sense HAT is capable of many things thanks to inventive use of the sensors or even just the code that controls it, and in this special digital edition we hope to inspire you to create some cool projects of your own. The Sense HAT costs £23/$39.95 and can be bought from the Below The Sense Swag Shop (magpi.cc/SenseHAT), Adafruit (magpi.cc/1TGGFy6) HAT is quite small, but packs a large or from any other distributor listed on the Raspberry Pi website number of sensors (magpi.cc/1TGGUt5). and features The LED matrix is a series The various sensors can be of 64 independently used to detect environmental programmable lights variables in the surrounding The Sense HAT fits neatly The joystick can be on top of the Raspberry used for inputs from Pi’s GPIO pins the SenseHAT [ What is the Sense HAT? ] 8 ESSENTIALS ESSENTIALS TWO [ CHAPTER ] HIGH FLIERS British ESA astronaut Tim Peake isn’t the only Brit aboard the International Space Station. David Crookes looks at how the Pi got into the sky and what it means for future generations. 99 [[ CChhaapptteerr OTwneo ]] [ EXPERIMENT WITH THE SENSE HAT ] n 15 December, British ESA astronaut Tim Peake made O history as the first British astronaut to visit the International Space Station. For the next six months, he will achieve most children’s dreams as he lives and works 400 kilometres above the Earth to carry out a comprehensive science programme during a mission called Principia. His role will be to run experiments using the unique environment of space and to try new technologies that may become crucial when humans begin to visit other planets such as Mars. But he will not be alone. Aside from living with five international colleagues, all of whom have spent years training for their difficult roles, Tim was greeted by another Brit, one set to accompany him throughout the whole of his time away from Earth. That extra ‘colleague’ is, of course, the British-made Raspberry Pi which, by the time Tim set off on a Soyuz spacecraft from Russia’s Baikonur cosmodrome in Kazakhstan, was already be waiting on board the ISS. Two Raspberry Pis were flown skywards on a Cygnus cargo freighter on 6 December, going ahead of Tim thanks to a lack of room on the Soyuz flight. But that meant the computers were ready and waiting to be unboxed by the time Tim arrived. The Raspberry Pi’s space adventure is referred to as the Astro Pi mission and, while it hasn’t been an easy ride for those involved, it certainly has been rewarding. That’s because the computers have each [ High Fliers ] 1100