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PiPhone interview with Dave Hunt

Turning your Raspberry Pi into a mobile phone is a lot simpler than you’d think, albeit a little chunky. Linux User talks to Dave Hunt about one of his many pet projects.

How did the idea come about for the PiPhone?

I did a presentation at a local conference a couple of weekends ago and I had to think of a topic. So I thought of the evolution of the PiPhone, where it came from.

It started with the Raspberry Pi; I had a project called the Camera Pi, which was embedding a Raspberry Pi into a battery grip of an SLR camera. That went viral; it was nuts because Engadget and everywhere covered this. I’d been waiting to do that project but I couldn’t do it until the Pi came out because everything else was either too expensive or too big. The Gumstix were around, and they were nice and small, but still over $200 at the time, then the Raspberry Pi came along and changed everything. So I started making with it and that got a good reaction, and I went on and started making time-lapse rails and bark- activated door openers and macro rails and all sorts of other stuff based on Raspberry Pis.

A simple interface for the touchscreen to dial and make calls, which can easily be improved upon
A simple interface for the touchscreen to dial and make calls, which can easily be improved upon

We really are living in a golden age for kids in terms of electronics: you can buy kits now that we never had –thatIneverhad–asakid.Youcan buy GPS units and GSM modules and pressure barometers and all these kits are freely available off Adafruit and via these DIY kits. It’s just a fantastic time to be living in for technology and it’s great that the Raspberry Pi is building on that and encouraging kids to get these bits and pieces and put them together. Which is what I’m doing with the PiPhone: it’s all just off-the-shelf parts that you can put together in a way that hadn’t really been done with a Raspberry Pi. It’s been done with Arduino but it never really caught on – maybe it’s the name that made the PiPhone go viral? Probably!

Have you seen anyone else make a PiPhone yet?

The bunch of people that have said that they’re building PiPhones is amazing, there are at least half a dozen people that are actually getting parts and I don’t know how many other people are thinking about it and doing it without letting people know. That’s the whole idea: get people building and get people playing with Linux even if they might not be that experienced with electronics. The whole PiPhone user interface is written in 150 lines of Python – it’s something that you can get your head around.

How usable is it as an actual phone in its current state?

Not very! It basically makes calls but it doesn’t receive calls. It makes calls pretty well; I’ve got the interface so it changes the green dial button to red when it’s making a call and when you hang up it goes back to green again. It tells you when it’s making a call and it establishes the call, and when you’ve got your headphones in you can talk and the red button will hang up the call. That part of it works quite well. Functionality- wise it’s only a few extra lines of Python to poll the GSM module for calling or listening for a string and then doing an ATA to answer the call. There’s nothing at all stopping anyone from adding the extra ten lines of Python to add an answering functionality into it. I’m just waiting to see who’s going to do that first – is it going to be one of the people building it? Are they going to extend it a little bit? That would be fantastic.

As for other functionality, there’s very little in there. Bearing in mind it’s a full Linux/X Windows system behind that Python interface.

What projects do you have planned with the Raspberry Pi in the future?

I’ve already moved on really. I’ve just got myself a 3D printer and I’m ramping up on that; I’ve already started a project that deals with parts and motors and Raspberry Pi’s driving motors and such, mounted on 3D prints in interesting ways.

I’ve done a time-lapse rail and I always wanted to add a panning head, so as well as moving sideways along a rail I always wanted the camera to be able to pan left, right, up and down in a rotational manner. I’m kind of working on that at the moment with parts printed on the 3D printer. It makes a lot of the tools in my shed totally obsolete – files and saws and all sorts of stuff that I would have had to use for making very complicated pieces. Now you just 3D print the part, mount a motor to it and it’s there.

So you should see lots more of that coming out but it’s still going to be all Raspberry Pi/Arduino based; there’s always going to be an embedded computer in it some way.

Components list

Raspberry Pi
PiTFT Touchscreen
2500mAh LiPo battery
SIM900 GSM/GPRS module
DC-DC boost converter 3.3V – 5V 1A

Feel inspired by the PiPhone? Check out RasPi magazine for project tutorials and more information about the Raspberry Pi, only 69p/99c an issue.