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Jun
8

Amazing Raspberry Pi Projects – Part 1

by Linux User & Developer

The £25 computer is celebrating its first anniversary a few months ago – here’s to a year’s worth of magnificent, unique and exciting achievements

As portable computing goes, the Raspberry Pi could hardly be bettered. Small enough to slip inside a pocket, it can go anywhere and everywhere with you. Yet to use the Pi as a standard Linux machine kind of misses the point – or, at the very least, the opportunities afforded by this small-form-factor, high-spec wonder.

Over the past year, this inexpensive machine, produced as an educational plaything, has taken centre stage for a whole host of projects. Some have satisfied a craving for fun; others for exploration and indulgence. More still have satisfied the current trend for performing real-world tasks at the lowest possible price. The Pi is the recession buster with the potential to empower a future generation (as one schoolboy emphatically showed).

Here we present ten of those projects. Each of them, we believe, encapsulates all that is good about the Pi, making great use of two things: the machine itself, with its tiny credit card size; but above all, the bold imagination of the creators. And the balls to keep going to realise those dreams, of course, but that would be three things.

Over the next few pages, the creators of these projects talk us through their projects. You will fi nd the majority of the source code on our cover disc and we’ll also tell you where you can fi nd tutorial instructions, where available, to allow you to replicate them. But more than all of this, we hope it provides you with inspiration for your own projects. You never know – you may see your creation here in a year’s time.

The Raspberry Pi Supercomputer

Take some Lego and 64 Pis for a delicious slice of processing power

Raspberry Pi
The supercomputer runs Rasbian OS

Since the ultimate aim of the Raspberry Pi is to encourage children to experiment with computers and understand their inner joy, the supercomputer project built by computational engineers at the University of Southampton could not be a better example of the magical things being done with this miniature marvel.

The creation by Professor Simon Cox and his team cost less than £2,500 to build, excluding the switches, but it also had a special ingredient: Prof Cox’s six-year-old son, James. It was while playing around with a Pi with his son that the supercomputer expert decided it would be an interesting experiment to buy 64 of the machines and produce something rather spectacular. And it was the young boy who provided specialist support on Lego and system testing, providing an eye-catching aspect to the entire project.

Running off a single 13 amp mains socket and using MPI to communicate between nodes using Ethernet, it offers a staggering amount of power when you consider the low cost.

Prof Cox had been impressed straight away by how great the Pi was for playing around with electronics using the GPIO connectors. “The fact you could turn LEDs on and off and link a little Python computer program to a bar graph LED caught the imagination of myself and my son who built a Lego case for it,” he tells us.

So he waited for a large supply of Pis to became available. “We then had to decide on the network switches. My background researching supercomputers and IT meant I knew you could spend a lot of money on switches. We begged, stole and borrowed some old switches that were being decommissioned from our computing service, which meant we could link them together. I got some power over Ethernet switches from another project I was working on.”

James used his design skills to build the racking out of little plastic bricks before testing it using Python and Scratch. But one of the most time-consuming processes was getting all of the images set up. Prof Cox found it was one thing to download one image on to one SD card, but quite another doing 64 of them.

“The Pi, for the first time, has meant you can assemble a supercomputer for a couple of thousand of pounds. And if you take just four of the units, suddenly you are at £100 and that means that large-scale supercomputing, or the principle of it, can be seen in schools. That’s very special.”

Eben Upton Says:

The thing about the Raspberry Pi is that suddenly things can be done that come within the budget of a school so you could actually have term-long projects and a whole class involved.

Picade arcade cabinet

No need to stand around in arcades – bring the action to your home

MAME
Picade opens up cabinets to the masses

Games have often been said to be a key driver of technology and so we were extremely excited to see the Picade project when it emerged on Kickstarter. Created by Jonathan Williamson and Paul Beech, it looks like a mini, retro-style cabinet and comes in kit form. All people need is a screwdriver, a pair of pliers and an hour of time to put it together.

“The idea had been in our heads for a while,” says Jonathan. “Paul and I have been through a number of startups and we had frequently seen a JAMMA cabinet in the office. It seemed the thing to have. We thought that only people with too much money or time on their hands were getting enjoyment out of them, so we decided it would be good to build one ourselves.”

The pair have been interested in technology for a long time and the Picade has been an accumulation of knowledge. From reading about joysticks to monitors, all of those ideas have come together. “We’ve also benefited from Kickstarter and globalisation,” says Paul. “Having the Pi was amazing.”

As if to underline just how the project has turned heads, Ian Stewart, the founder of Sheffield’s Gremlin Graphics – a games developer big in the Eighties and early Nineties – has allowed the use of the fi rm’s old-school games. “This means we can provide a games machine that can be used straight away,” says Paul. “And when you look at the Pi Store, the Picade suddenly becomes a great way to play legal games.”

Jonathan is excited about the future. “It’s the 3D games which I am loving,” he enthuses. “It will show off the Pi as a great gaming machine.” However, there have been some problems encountered by the pair. “Screens,” says Paul. “There are tons of models out there and some of these are 3mm in width. You can’t believe how thin they are. We had to look at how easy they are to mount, and separating wheat from the chaff. There is always a delay in stock too and we have to get on with other stuff while waiting for things to appear. Trying to get quality parts on time is diffi cult. A lot of components have to come from the East, such as arcade joysticks. But it’s been brilliant to work on.”

Eben Upton says:

There are those little specialist niche markets. The Raspberry Pi lets you do things which were previously very expensive if you are prepared to get your hands dirty and hack a bit.

Lego remotecontrolled car

A Pi-powered self-contained remote-controlled car guided by an Xbox controller

Raspberry Pi Remote Control
All the hardware lives on the car itself

Very often what you didn’t have in your childhood inspires you in adulthood. That was the case with the Lego remote-controlled car created by Tom Rees using the Raspberry Pi. Having always wanted a remote-controlled car when he was young, the desire never left him.

And thanks to the power of the Pi, he was also able to go one better. Rather than build something controlled on a long tether to a computer or via Wi-Fi from a laptop, Tom could integrate the computer into the car itself. This means it became a ‘real’ remote-controlled car comprising just the vehicle and the controller.

The original plan was to build an RC Lego DeLorean, but all he could produce was an ugly white box. He then came up with different prototypes, most of which looked nothing like a car and were essentially motors, servos and LEDs attached to Technic towers. “I remember the very fi rst thing I built was a pair of LEDs which were turned on and off by the Xbox controller,” he says. “It’s important to begin with the simplest possible proof-of-concept to show all parts of the system working.”

To even begin to prototype, jumper wires, breadboards, a multimeter and lots of batteries were needed, plus a selection of resistors, capacitors, LEDs and a soldering iron. Once Tom had all the necessary supplies, he just decided to dive in. He learned as he went along.

“I had plenty of disasters,” he admits. “The cheap inductors I used in the 5V power regulator kept catching fire because the Pi consumes so much current. Smoke pouring out of the Lego Technic holes is pretty terrifying.”

Trickiest of all was powering the electronics aboard the car. “The Raspberry Pi has strict tolerances on its 5V input, and it will consume well over 1 amp when the Microsoft USB peripheral is attached,” he says. But he is more
than pleased with the result.

“Most stunning has been the reaction to this project. I knew I wanted to do something original with my Pi, to push the envelope very slightly, and be a little more imaginative than another ‘internet-controlled LEDs’ project. It’s seen a great reaction and I’m very pleased to see some projects inspired by this one.”

Eben Upton Says

I think the thing that has really encouraged me is if you actually look at the number of these things where the Pi is a tool, it is not the Pi that is really the hit, it is the thing around it that is really the piece of inventive genius.

Light painting with the Pi

Artistic images that simply astound are possible with the power of Pi

Raspberry Pi lightpainting
An Arduino could handle the tas, but required a ton of preprocessing and staging of the image data in flash storage

There is seldom a more stunning effect than light painting. It uses long exposure times with lights in motion to produce amazing images. When Phil Burgess wanted to produce a machine that could create effective artistic images, he had a hunch that the Raspberry Pi would be able to streamline the process, not least because of the memory it could provide for the project.

The concept had been stewing for months, but no existing device made for a really satisfactory solution, Phil says, and by that he meant something that could be shared and easily built by others. The open source electronic prototyping platform Arduino was considered and Phil says it could handle the core task but it requires a ton of preprocessing and staging of the image data in flash storage. The Pi could handle this – and because it is inexpensive, it got over the worry of getting it damaged.

“So far we have created the prototype,” Phil tells us. “The next version will be smaller and lighter with a proper battery pack. At the time I was just scrambling among parts in the garage and relied on an enormous camping inverter to quickly solve the problem at hand.” Things went well too. “All the hardware and software was amazingly co-operative and everything fell into place,” Phil adds.

The trickiest part of the project was the documentation. “Explaining things as concisely as possible, cleaning up the code to be presentable, providing clear diagrams and such is always hard,” comments Phil. “Good documentation can elevate even a modest project into something desirable, but no amount of ‘coolness’ in a project can cover for
a lousy explanation.”

And there were other considerations. A 5V DC power supply was needed because the LED strip draws so much more power than the micro-USB connector can provide. A 26-pin IDC cable was sacrificed to create a purpose-built cable between the Raspberry Pi GPIO header, LED strip and power supply in order to make the whole project more robust.

Phil also says Python warrants a mention: “My first attempts at communicating with the LED strip were in C, but if this project was to be shared, C with makefiles and extra libraries and such would add complexity. In 48 hours, starting with zero Python exposure, it was possible to get this not just working, but actually pretty well optimised as I got a better handle on the language. And it’s all in one source file, easily shared.”

Read Part 2

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