Author Archives: Janina Ander

Manufacturing Astro Pi case replicas

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Tim Rowledge produces and sells wonderful replicas of the cases which our Astro Pis live in aboard the International Space Station. Here is the story of how he came to do this. Over to you, Tim!

When the Astro Pi case was first revealed a couple of years ago, the collective outpouring of ‘Squee!’ it elicited may have been heard on board the ISS itself. People wanted to buy it or build it at home, and someone wanted to know whether it would blend. (There’s always one.)

The complete Astro Pi

The Sense HAT and its Pi tucked snugly in the original Astro Pi flight case — gorgeous, isn’t it?

Replicating the Astro Pi case

Some months later the STL files for printing your own Astro Pi case were released, and people jumped at the chance to use them. Soon reports appeared saying you had to make quite a few attempts before getting a good print — normal for any complex 3D-printing project. A fellow member of my local makerspace successfully made a couple of cases, but it took a lot of time, filament, and post-print finishing work. And of course, a plastic Astro Pi case simply doesn’t look or feel like the original made of machined aluminium — or ‘aluminum’, as they tend to say over here in North America.

Batch of tops of Astro Pi case replicas by Tim Rowledge

A batch of tops designed by Tim

I wanted to build an Astro Pi case which would more closely match the original. Fortunately, someone else at my makerspace happens to have some serious CNC machining equipment at his small manufacturing company. Therefore, I focused on creating a case design that could be produced with his three-axis device. This meant simplifying some parts to avoid expensive, slow, complex multi-fixture work. It took us a while, but we ended up with a design we can efficiently make using his machine.

Lasered Astro Pi case replica by Tim Rowledge

Tim’s first lasered case

And the resulting case looks really, really like the original — in fact, upon receiving one of the final prototypes, Eben commented:

“I have to say, at first glance they look spectacular: unless you hold them side by side with the originals, it’s hard to pinpoint what’s changed. I’m looking forward to seeing one built up and then seeing them in the wild.”

Inside the Astro Pi case

Making just the bare case is nice, but there are other parts required to recreate a complete Astro Pi unit. Thus I got my local electronics company to design a small HAT to provide much the same support the mezzanine board offers: an RTC and nice, clean connections to the six buttons. We also added well-labelled, grouped pads for all the other GPIO lines, along with space for an ADC. If you’re making your own Astro Pi replica, you might like the Switchboard.

The electronics supply industry just loves to offer *some* of what you need, so that one supplier never has everything: we had to obtain the required stand-offs, screws, spacers, and JST wires from assorted other sources. Jeff at my nearby Industrial Paint & Plastics took on the laser engraving of our cases, leaving out copyrighted logos etcetera.

Lasering the top of an Astro Pi case replica by Tim Rowledge

Lasering the top of a case

Get your own Astro Pi case

Should you like to buy one of our Astro Pi case kits, pop over to www.astropicase.com, and we’ll get it on its way to you pronto. If you’re an institutional or corporate customer, the fully built option might make more sense for you — ordering the Pi and other components, and having a staff member assemble it all, may well be more work than is sensible.

Astro Pi case replica Tim Rowledge

Tim’s first full Astro Pi case replica, complete with shiny APEM buttons

To put the kit together yourself, all you need to do is add a Pi, Sense HAT, Camera Module, and RTC battery, and choose your buttons. An illustrated manual explains the process step by step. Our version of the Astro Pi case uses the same APEM buttons as the units in orbit, and whilst they are expensive, just clicking them is a source of great joy. It comes in a nice travel case too.

Tim Rowledge holding up a PCB

This is Tim. Thanks, Tim!

Take part in Astro Pi

If having an Astro Pi replica is not enough for you, this is your chance: the 2017-18 Astro Pi challenge is open! Do you know a teenager who might be keen to design a experiment to run on the Astro Pis in space? Are you one yourself? You have until 29 October to send us your Mission Space Lab entry and become part of the next generation of space scientists? Head over to the Astro Pi website to find out more.

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Sean Hodgins’ Haunted Jack in the Box

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After making a delightful Bitcoin lottery using a Raspberry Pi, Sean Hodgins brings us more Pi-powered goodness in time for every maker’s favourite holiday: Easter! Just kidding, it’s Halloween. Check out his hair-raising new build, the Haunted Jack in the Box.

Haunted Jack in the Box – DIY Raspberry Pi Project

This project uses a raspberry pi and face detection using the pi camera to determine when someone is looking at it. Plenty of opportunities to scare people with it. You can make your own!

Haunted jack-in-the-box?

Imagine yourself wandering around a dimly lit house. Your eyes idly scan a shelf. Suddenly, out of nowhere, a twangy melody! What was that? You take a closer look…there seems to be a box in jolly colours…with a handle that’s spinning by itself?!

Sidling up to Sean Hodgins' Haunted Jack in the Box

What’s…going on?

You freeze, unable to peel your eyes away, and BAM!, out pops a maniacally grinning clown. You promptly pee yourself. Happy Halloween, courtesy of Sean Hodgins.

Clip of Sean Hodgins' Haunted Jack in the Box

Eerie disembodied voice: You’re welco-o-o-ome!

How has Sean built this?

Sean purchased a jack-in-the-box toy and replaced its bottom side with one that would hold the necessary electronic components. He 3D-printed this part, but says you could also just build it by hand.

The bottom of the box houses a Raspberry Pi 3 Model B and a servomotor which can turn the windup handle. There’s also a magnetic reed switch which helps the Pi decide when to trigger the Jack. Sean hooked up the components to the Pi’s GPIO pins, and used an elastic band as a drive belt to connect the pulleys on the motor and the handle.

Film clip showing the inside of Sean Hodgin's Haunted Jack in the Box

Sean explains that he has used a lot of double-sided tape and superglue in this build. The bottom and top are held together with two screws, because, as he describes it, “the Jack coming out is a little violent.”

In addition to his video walk-through, he provides build instructions on Instructables, Hackaday, Hackster, and Imgur — pick your poison. And be sure to subscribe to Sean’s YouTube channel to see what he comes up with next.

Wait, how does the haunted part work?

But if I explain it, it won’t be scary anymore! OK, fiiiine.

With the help of a a Camera Module and OpenCV, Sean implemented facial recognition: Jack knows when someone is looking at his box, and responds by winding up and popping out.

View of command line output of the Python script for Sean Hodgins' Haunted Jack in the Box

Testing the haunting script

Sean’s Python script is available here, but as he points out, there are many ways in which you could adapt this code, and the build itself, to be even more frightening.

So very haunted

What would you do with this build? Add creepy laughter? Soundbites from It? Lighting effects? Maybe even infrared light and a NoIR Camera Module, so that you can scare people in total darkness? There are so many possibilities for this project — tell us your idea in the comments.

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BrailleBox: Android Things Braille news display

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Joe Birch has built a simple device that converts online news stories to Braille, inspired by his family’s predisposition to loss of eyesight. He has based his BrailleBox on Android Things, News API, and a Raspberry Pi 3.

Demonstation of Joe Birch's BrailleBox

The background

Braille is a symbol system for people with visual impairment which represents letters and numbers as raised points. Commercial devices that dynamically produce Braille are very expensive, so Joe decided to build a low-cost alternative that is simple to recreate.

Braille alphabet

Image by DIPF CC BY-SA 3.0

News API is a tool for fetching JSON metadata from over 70 online news sources. You can use it to integrate headlines or articles into websites and text-based applications.

The BrailleBox

To create the six nubs necessary to form Braille symbols, Joe topped solenoids with wooden balls. He then wired them up to GPIO pins of the Pi 3 via a breadboard.

One of the solenoids of Joe Birch's BrailleBox

One of the solenoids Joe built into the BrailleBox

Next, he took control of the solenoids using Android Things. He set up the BrailleBox software to start running on boot, and added a push button. When he presses the button, the program fetches a news story using News API, and the solenoids start moving.

BrailleBox Demo

Uploaded by Joe Birch on 2017-06-20.

Since Joe is an Android Engineer, looking through his write-up and code for BrailleBox might be useful for anyone interested in Android Things.

If you like this project, make sure you keep an eye on Joe’s Twitter, since he has plans to update the BrailleBox design. His next step is to move on from the prototyping stage and house all the hardware inside the box. Moreover, he is thinking about adding a potentiometer so that users can choose their preferred reading speed.

Accessibility

If you want to find our community’s conversation about accessibility and assistive technology, head to the forums. And if you’re working to make computing more accessible, or if you’ve built an assistive project, let us know in the comments or on social media, so that we can boost the signal!

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RaspiReader: build your own fingerprint reader

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Three researchers from Michigan State University have developed a low-cost, open-source fingerprint reader which can detect fake prints. They call it RaspiReader, and they’ve built it using a Raspberry Pi 3 and two Camera Modules. Joshua and his colleagues have just uploaded all the info you need to build your own version — let’s go!

GIF of fingerprint match points being aligned on fingerprint, not real output of RaspiReader software

Sadly not the real output of the RaspiReader

Falsified fingerprints

We’ve probably all seen a movie in which a burglar crosses a room full of laser tripwires and then enters the safe full of loot by tricking the fingerprint-secured lock with a fake print. Turns out, the second part is not that unrealistic: you can fake fingerprints using a range of materials, such as glue or latex.

Examples of live and fake fingerprints collected by the RaspiReader team

The RaspiReader team collected live and fake fingerprints to test the device

If the spoof print layer capping the spoofer’s finger is thin enough, it can even fool readers that detect blood flow, pulse, or temperature. This is becoming a significant security risk, not least for anyone who unlocks their smartphone using a fingerprint.

The RaspiReader

This is where Anil K. Jain comes in: Professor Jain leads a biometrics research group. Under his guidance, Joshua J. Engelsma and Kai Cao set out to develop a fingerprint reader with improved spoof-print detection. Ultimately, they aim to help the development of more secure commercial technologies. With their project, the team has also created an amazing resource for anyone who wants to build their own fingerprint reader.

So that replicating their device would be easy, they wanted to make it using inexpensive, readily available components, which is why they turned to Raspberry Pi technology.

RaspiReader fingerprint scanner by PRIP lab

The Raspireader and its output

Inside the RaspiReader’s 3D-printed housing, LEDs shine light through an acrylic prism, on top of which the user rests their finger. The prism refracts the light so that the two Camera Modules can take images from different angles. The Pi receives these images via a Multi Camera Adapter Module feeding into the CSI port. Collecting two images means the researchers’ spoof detection algorithm has more information to work with.

Comparison of live and spoof fingerprints

Real on the left, fake on the right

RaspiReader software

The Camera Adaptor uses the RPi.GPIO Python package. The RaspiReader performs image processing, and its spoof detection takes image colour and 3D friction ridge patterns into account. The detection algorithm extracts colour local binary patterns … please don’t ask me to explain! You can have a look at the researchers’ manuscript if you want to get stuck into the fine details of their project.

Build your own fingerprint reader

I’ve had my eyes glued to my inbox waiting for Josh to send me links to instructions and files for this build, and here they are (thanks, Josh)! Check out the video tutorial, which walks you through how to assemble the RaspiReader:

RaspiReader: Cost-Effective Open-Source Fingerprint Reader

Building a cost-effective, open-source, and spoof-resilient fingerprint reader for $160* in under an hour. Code: https://github.com/engelsjo/RaspiReader Links to parts: 1. PRISM – https://www.amazon.com/gp/product/B00WL3OBK4/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1 (Better fit) https://www.thorlabs.com/thorproduct.cfm?partnumber=PS611 2. RaspiCams – https://www.amazon.com/gp/product/B012V1HEP4/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1 3. Camera Multiplexer https://www.amazon.com/gp/product/B012UQWOOQ/ref=oh_aui_detailpage_o04_s01?ie=UTF8&psc=1 4. Raspberry Pi Kit: https://www.amazon.com/CanaKit-Raspberry-Clear-Power-Supply/dp/B01C6EQNNK/ref=sr_1_6?ie=UTF8&qid=1507058509&sr=8-6&keywords=raspberry+pi+3b Whitepaper: https://arxiv.org/abs/1708.07887 * Prices can vary based on Amazon’s pricing. P.s.

You can find a parts list with links to suppliers in the video description — the whole build costs around $160. All the STL files for the housing and the Python scripts you need to run on the Pi are available on Josh’s GitHub.

Enhance your home security

The RaspiReader is a great resource for researchers, and it would also be a terrific project to build at home! Is there a more impressive way to protect a treasured possession, or secure access to your computer, than with a DIY fingerprint scanner?

Check out this James-Bond-themed blog post for Raspberry Pi resources to help you build a high-security lair. If you want even more inspiration, watch this video about a laser-secured cookie jar which Estefannie made for us. And be sure to share your successful fingerprint scanner builds with us via social media!

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Algo-rhythmic PianoAI

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It’s no secret that we love music projects at Pi Towers. On the contrary, we often shout it from the rooftops like we’re in Moulin Rouge! But the PianoAI project by Zack left us slack-jawed: he built an AI on a Raspberry Pi that listens to his piano playing, and then produces improvised, real-time accompaniment.

Jamming with PIanoAI (clip #1) (Version 1.0)

Another example of a short teaching and then jamming with piano with a version I’m more happy with. I have to play for the Pi for a little while before the Pi has enough data to make its own music.

The PianoAI

Inspired by a story about jazz musician Dan Tepfer, Zack set out to create an AI able to imitate his piano-playing style in real time. He began programming the AI in Python, before starting over in the open-source programming language Go.

The Go language gopher mascot with headphones and a MIDI keyboard

The Go mascot is a gopher. Why not?

Zack has published an excellent write-up of how he built PianoAI. It’s a very readable account of the progress he made and the obstacles he had to overcome while writing PianoAI, and it includes more example videos. It’s hard to add anything to Zack’s own words, so I shan’t try.

Paper notes for PianoAI algorithm

Some of Zack’s notes for his AI

If you just want to try out PianoAI, head over to his GitHub. He provides a detailed guide that talks you through how to implement and use it.

Music to our ears

The Raspberry Pi community never fails to amaze us with their wonderful builds, not least when it comes to musical ones. Check out this cool-looking synth by Toby Hendricks, this geometric instrument by David Sharples, and this pyrite-disc-reading music player by Dmitry Morozov. Aren’t they all splendid? And the list goes on and on

Which instrument do you play? The recorder? The ocarina? The jaw harp? Could you create an AI like Zack’s for it? Let us know in the comments below, and share your builds with us via social media.

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The possibilities of the Sense HAT

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Did you realise the Sense HAT has been available for over two years now? Used by astronauts on the International Space Station, the exact same hardware is available to you on Earth. With a new Astro Pi challenge just launched, it’s time for a retrospective/roundup/inspiration post about this marvellous bit of kit.

Sense HAT attached to Pi and power cord

The Sense HAT on a Pi in full glory

The Sense HAT explained

We developed our scientific add-on board to be part of the Astro Pi computers we sent to the International Space Station with ESA astronaut Tim Peake. For a play-by-play of Astro Pi’s history, head to the blog archive.

Astro Pi logo with starry background

Just to remind you, this is all the cool stuff our engineers have managed to fit onto the HAT:

  • A gyroscope (sensing pitch, roll, and yaw)
  • An accelerometer
  • A magnetometer
  • Sensors for temperature, humidity, and barometric pressure
  • A joystick
  • An 8×8 LED matrix

You can find a roundup of the technical specs here on the blog.

How to Sense HAT

It’s easy to begin exploring this device: take a look at our free Getting started with the Sense HAT resource, or use one of our Code Club Sense HAT projects. You don’t even need to own one in order to dive in. Emulators are available offline on Raspbian and online on Trinket.

Sense HAT emulator on Trinket

The Sense HAT emulator on trinket.io

Fun and games with the Sense HAT

Use the LED matrix and joystick to recreate games such as Pong or Flappy Bird. Of course, you could also add sensor input to your game: code an egg drop game or a Magic 8 Ball that reacts to how the device moves.

Sense HAT Random Sparkles

Create random sparkles on the Sense HAT

Once December rolls around, you could brighten up your home with a voice-controlled Christmas tree or an advent calendar on your Sense HAT.

If you like the great outdoors, you could also use your Sense HAT to recreate this Hiking Companion by Marcus Johnson. Take it with you on your next hike!

Art with the Sense HAT

The LED matrix is perfect for getting creative. To draw something basic without having to squint at a Python list, use this app by our very own Richard Hayler. Feeling more ambitious? The MagPi will teach you how to create magnificent pixel art. Ben Nuttall has created this neat little Python script for displaying a photo taken by the Raspberry Pi Camera Module on the Sense HAT.

Brett Haines Mathematica on the Sense HAT

It’s also possible to incorporate Sense HAT data into your digital art! The Python Turtle module and the Processing language are both useful tools for creating beautiful animations based on real-world information.

A Sense HAT project that also uses this principle is Giorgio Sancristoforo’s Tableau, a ‘generative music album’. This device creates music according to the sensor data:

Tableau Generative Album

“There is no doubt that, as music is removed by the phonographrecord from the realm of live production and from the imperative of artistic activity and becomes petrified, it absorbs into itself, in this process of petrification, the very life that would otherwise vanish.”

Science with the Sense HAT

This free Essentials book from The MagPi team covers all the Sense HAT science basics. You can, for example, learn how to measure gravity.

Cropped cover of Experiment with the Sense HAT book

Our online resource shows you how to record the information your HAT picks up. Next you can analyse and graph your data using Mathematica, which is included for free on Raspbian. This resource walks you through how this software works.

If you’re seeking inspiration for experiments you can do on our Astro Pis Izzy and Ed on the ISS, check out the winning entries of previous rounds of the Astro Pi challenge.

Thomas Pesquet with Ed and Izzy

Thomas Pesquet with Ed and Izzy

But you can also stick to terrestrial scientific investigations. For example, why not build a weather station and share its data on your own web server or via Weather Underground?

Your code in space!

If you’re a student or an educator in one of the 22 ESA member states, you can get a team together to enter our 2017-18 Astro Pi challenge. There are two missions to choose from, including Mission Zero: follow a few guidelines, and your code is guaranteed to run in space!

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