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Amazing Raspberry Pi Projects – Part 2

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We continue our countdown of the top 10 amazing Raspberry Pi projects

The one-button audio player

Music to a grandma’s ears…it’s the easy-to-use audio player

Raspberry Pi Audible
The difficult part came in automatic mounting of the USB flash drive and deleting the old audiobook

Michael Clemens’s idea for his Raspberry Pi project came less out of hobbyism and more out of a solution to a very personal problem. His wife’s grandmother is visually impaired and the couple find it difficult to keep her entertained. Listening to television is not ideal and she struggles to operate her CD player.

With her 90th birthday approaching, Michael sought a solution: to build an audiobook player that was inexpensive and easy to operate, with as few buttons as possible. It also needed to be open source. The Raspberry Pi was the answer.

“The idea came quick, but planning it through and building it was kind of fragmented because my work includes travelling,” he says. “When I knew what I wanted, I soldered the button and LED to a board that could be connected via the GPIO pins and then I used a little Python coding and configuration of standard Linux software for the rest. Being no good coder or expert in electronics, this was the simplest way to achieve my goals.”

The sound quality can crack when you play or resume an MP3. “But,” Michael says, “that is a known problem in the Raspberry Pi community. The quality of the device itself is quite solid, but I’m thinking about building a new, large enclosure out of wood for the player together with the speakers.”

Time-lapse photography with Pysnap

The competition-winning CLI tool created by a talented schoolboy

It was a contest for young programmers, but few would have expected to see quality of the type produced by 12-year-old Aaron Hill, who ran away with first prize in the under-13 category.

His success? Amazing software that turns a Raspberry Pi computer into a time-lapse camera. By connecting a USB camera to a Pi and running the software, it is possible to fine-tune the interval at which it takes pictures.

“My aunt has a motion-sensing camera set up in the woods near their hunting stand. That triggered the idea,” Aaron tells us. “The first thing that I did was to find out how I would get the program to take the pictures… I discovered a command-line program called Streamer, which was in the Debian and Ubuntu repos. I installed it and, after playing around with it, decided that I would use it for my project. Next, I started writing the actual code. I started off with just adding the option to choose different time intervals: seconds, minutes and hours. Later I got the idea to allow taking of pictures on a specific day, and a specific time.”

One feature he initially liked but ended up discarding was having the program print out text one character at a time, instead of all at once. The effect wasn’t very noticeable with a fast speed, and irritating to the user if it was slower, he says. And although he didn’t have the GUI ready in time for the content, there was enough to prove that Aaron was very much on to a good thing.

Pi-Face – the digital interface

Let the Raspberry Pi be the hub to your digital life

The Pi-Face is credit card sized and it stacks on top of the Raspberry Pi. It is buffered to protect the Pi

Being able to control the real world using a computer is the sort of thing that we wanted back in the mid-Eighties when watching Back To The Future. There have been lots of solutions for this issue, but none has been as cost effective and wide open as the Pi-Face Digital Interface created by scientists at Manchester University.

“I’d been working on getting more people interested in computing for a few years,” explains Dr Andrew Robinson, the brains behind the device. “I was really excited to hear Raspberry Pi was coming along, but worried that people wouldn’t know what to do with it. I saw the interface as a missing link, to allow people to put the Raspberry Pi where they wouldn’t put a PC and connect it up to the world. So I designed Pi-Face to be ready for when the Raspberry Pi came out, and planned some fun activities – like the twittering chicken.”

The first design was published on 15 December 2011 and the interface board is the same size as the Raspberry Pi. It slots onto the GPIO pins and has screw terminals so it’s very easy to connect up switches to sense things and lights/motors for the Raspberry Pi to control. It’s very easy to program in Scratch or Python too. It’s not just about the interface, either. The project is also about creating the fun activities and tutorials to support using the Raspberry Pi.

“It took four prototypes to get right,” says Dr Robinson. “The fi rst one has a yellow wire tacked on because a connection got missed. It was a bit like the early Raspberry Pis that also had bits of wire tacked on by hand.”

Apart form that, it has all gone rather smoothly, however. “The interface has been designed to take some abuse since it’s targeted at beginners,” he adds. “We’ve connected things up wrongly a few times, but so far not seen any smoke! On the workshop side of things, the children have really loved it. We have a harder time when we run the workshops for teachers! Still we’ve learned from it.”

Pi in the sky – 40km high photography

A record-breaking balloon mission records stunning near-space photos

Pi in the sky, looking at you
In the future, Dave wants to use the forthcoming Pi Camera

It’s hard to say what is more amazing – the photographs taken high up in space or Dave Akerman’s Raspberry Pi/webcam/GPS/hydrogen balloon combination which enabled him to capture such magnificent shots.

Not only are they believed to be the highest ever photographs transmitted live from an amateur device, the ability to thrust a Raspberry Pi into space is an amazing feat. And it barely took Dave any time at all to figure out, making it all the more extraordinary.

“The idea to combine the Pi and a weather balloon came after I took delivery of the Pi,” he tells us. “I ordered it just because I was curious, and didn’t really have any use planned for it. By then I’d been flying weather balloons with Arduino trackers for about a year, and thought that it would be fun to fly the Pi instead. The Arduino is ideal as a basic tracker, but the Pi does make it much easier to add things like live picture downloads.”

It took about an hour to wire up a radio transmitter and GPS, and another hour to port Dave’s Arduino code over to the Pi. At that point he had a working Pi tracker and he was keen to fly it just to be the first to do so. But the weather remained poor and he couldn’t launch for two weeks. That gave him time to add some more capability.

“Adding a live image download was obvious, since the Pi can interface very easily to a USB webcam,” Dave says. “It was a couple of days’ work to get that working. After that I had to make a regulator so the tracker could run from batteries.”

He kept quiet about his project because he wanted to do it before anyone else. He didn’t say when the launch was planned either. “The launch itself was fairly stressful – as they usually are – but particularly this time because it was a new tracker and the first time I’d transmitted live images,” he admits. “I had two trackers to get ready, one as a backup, and a friend added his payload with a GoPro camera. So it was quite a complex launch and it made an impressive sight as it went up.”

Eben Upton Says:

I’m just about young enough to be a space cadet. I remember staying up when I was a kid to watch the first shuttle launch. Dave Akerman was sending down images from 40 kilometres up. That is wonderful.

Brew beer with BrewPi

Retaliation-inspired mobile missile launcher Relax with a cool beer (and maybe a pie) thanks to the magic of the Pi

The Pi replaced a Linksys Router solution originally called UberFridge

Elco Jacobs loves his beer. So much so that he makes his own. What he has found, however, is that a tasty brew can be enhanced using the power of the Raspberry Pi. This capability led to the forming of the BrewPi project with three aims: to control the temperature of his fermenting beers, log temperature data into graphs and the ability to slowly raise or lower the beer temperature.

Elco had experimented with analog temperature sensors, which were noisy and needed a lot of software filtering, so he replaced them with more accurate digital OneWire sensors. He also ditched floatingpoint filtering and used fixed point. BrewPi uses solidstate relays which are safe and quiet. Elco also dropped the idea of a threebutton interface in favour of a rotary encoder interface, which is much more intuitive.

Eben Upton

Things like this let me have thermostatically controlled beer brewing!

Retaliation-inspired mobile missile launcher

This simple foam-missile project is a great way to inspire young coders

When the enemy attacks in the night

This offi ce missile launcher is an inventive use of the Pi and while not original (the inspiration came from Retaliation), the portable nature of the Pi has proved a perfect fit. “The original project had a few limitations,” says Nathan Byrd. “Using a full computer for this project requires one to be on all the time or at least whenever there are people there to shoot…and greatly limits the placement of the missile launcher. With the Raspberry Pi I could mount it just about anywhere and leave it on all the time without requiring a full computer.”

Nathan bought the Pi to teach his 11 year old son to program and familiarise him with hardware. Retaliation worked in this regard too: “What 11 year old, or adult for that matter, doesn’t love shooting foam missiles around the house?” Nathan had to order the missile launcher, then find the packages and software, before testing and documenting the build. Hooking it up without a powered USB hub proved a problem so there was a bit of soldering involved (although that is no longer the case with newer revisions of the Raspberry Pi). And along the way they had to shoot lots of foam missiles at each other.

Read Part 1

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