Hack Your Phone: Turn Your Volume Buttons Into GPIO Ports

Internet connected cameras are mighty useful, specially in situations requiring some form of remote monitoring. An always-on camera that is available over an internet connection, is cheap, and uses re-purposed  hardware – that’s what the Gonzo project hopes to achieve. To accommodate these requirements, the Exploratory Engineering program team in Telenor Digital are using off-the-shelf phone hardware running on top of a fork of Firefox OS. You hang the Gonzo where you want to monitor a situation, after which it will function for up to one month before needing a recharge, sending data to a designated public URL over the 2G network.

A big downside with using such hardware is that it is not designed for the task at hand, and offers no expansion ports that may be needed for certain functions. In this particular case, the designers needed a couple of output ports to drive some LED’s. The hardware guys got a bit creative,  and re-mapped the volume buttons of the phone into generic GPIO ports. On the software side, they looked at where the button GPIO’s were referenced, and located how they are mapped to a keymap. They then added a device driver that maps the GPIO ports to be generic ports instead. Modding the hardware needed a little bit more hard work, figuring out which traces connected to the two volume buttons, adding series resistors, and then wiring the LED’s in place. The project itself is still a work in progress, and you can read more about it at the Gonzo website.

If you’re like one of us and have a box full of old phones lying around, take a look at some creative suggestions here for some Arduino controlled robots.

Thanks for the tip [pb] !

9 thoughts on “Hack Your Phone: Turn Your Volume Buttons Into GPIO Ports

    1. They are using a Geeksphone Keon, which was sold out in the first few hours of being offered. If you would like one, grab the successor, the Geeksphone Revolution.

      This kinda contradicts your misinformed babbling, doesn’t it?

      1. it was a $150 dev platform for horrible os – never sold to consumers, and is unobtanium
        website states Gonzo mission is to turn “cheap as possible, at a throw-away price point, off the shelf hardware” into web cameras. This particular phone doesnt cover any of those criteria.

        Now you might say wait a minute, there are cheap firefox OS phones sold in Azerbaijan and Sudan!
        this is camera quality from those “affordable” >$50 phones

        so again, meh, ill stick with $100 fullHD hikvision IP cameras/ $50 pee with camera module/ or even that $35 bananapi 720p IP camera platform

  1. I honestly wish I could make use of all the obsolete smartphones and tablets I have lying around, I can’t even give them away as most people I know already own better devices (or they don’t feel the need to use a smartphone)… I wish there were an easy way to turn them into SBCs, BeagleBone Black or Rasperry PI alternatives, old Android devices are great and all, but still very limited due to their security measures, closed source hardware, lack of easily accessible GPIO and very little documentation…

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