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Low-cost, low-bandwidth wireless Arduino to Android communications

android_nfc

[Joe] was experimenting with his Arduino when he started thinking about how he could get it to communicate wirelessly with his Android phone. Bluetooth is an option, but it requires some extra components, and Google’s ADK works as well – just not wirelessly.

Instead, he thought it would be neat to see if he could get the two devices to communicate with a simple magnetic coil. He constructed a small 1cm diameter coil, connecting it to the Arduino via a resistor and diode. Using the Android Tricorder app, he was able to locate his phone’s magnetometer, after which he ran some tests to narrow down the best sample rate and frequency range for communications.

To transfer data between the two devices, he had to bit bang the signal in software, since the Arduino’s UART has a lower limit far faster than the 7 bps data rate he was able to achieve with the magnetometer.

While his wireless Arduino to Android bridge isn’t likely to win any awards for throughput, it is a great proof of concept project. Be sure to check out the video below to see his “poor man’s NFC” in action.

Comments

  1. Muzza says:

    wow very cool…. not particularly useful but cool none the less! I would never have thought to use the magnetometer as a data interface!

  2. Panikos says:

    so out of the box. i like it. it must have been a fun few hours getting that done!

  3. Zee says:

    Now that is some impressive hacking

  4. GTMoogle says:

    Well, it is a 3 axis magnetometer, he might be able to up the data rate by encoding more data in the direction of the magnetic field.

  5. steaky says:

    @GTMoogle
    He states in the article about the 3-axis stuff.
    Not very useful, but very impressive

  6. Muzza says:

    @GTMoogle

    3 axis would be the accelerometer, I think he has interfaced with the digital compass… would be a bit difficult to generate a 3 axis artificial gravity interface! who’s up to the challenge??

  7. Aakash says:

    Whoa! A new (useless) idea – a shaking platform which transfers data wirelessly to the phone, using the phone’s accelerometer :D

  8. marclurr says:

    Sounds excellent but that video doesn’t really demonstrate it.

  9. The Doctor says:

    Most impressive.

  10. wow man, this is GREAT!

  11. John says:

    Great use of the tricorder app!

  12. Anonymous says:

    might there be a way to inject data to an application utilising the sensor?

  13. yetihehe says:

    I think acoustic coupling would be faster.

  14. Beautiful! I’ve been doing acoustic coupling for a while now and wouldn’t like this method because it effectively disables your compass, but this is how it’s done — simple and clever

  15. Tobie Nortje says:

    I mean, this is what hacking is all about!

    It does not have to be super useful, but thats what we do!

    This might just trigger the cellphone people to install a simple radio system in their phones to make things even simpler!

    i thought this was super cool!

  16. Harvie.CZ says:

    Can attach the coil to audio output of another android device?

  17. symndz says:

    what about multibit encoding, since this isn’t digital interface? think about that :)

  18. Mike says:

    You could use the 6 DOF sensors by making a rig that moves and rotates the phone in x,y,z, like a shaker rig modem.

    But that’s just crazy…

  19. he might be able to up the data rate by encoding more data in the direction of the magnetic field.

  20. Max says:

    Ok, what’s next? Having an LED dot matrix block display QR codes and have the phone decode them using it’s camera? It might actually be faster… :P

  21. auxiliary-character says:

    Wouldn’t the coil in the microphone be faster? Neat hack, though.

  22. arno says:

    does the phone talk back?

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