Create Cheap Arduino-to-Android Wireless with a Magnetic Coil
Have you ever wanted to find an inexpensive way of communicating with your Android phone wirelessly, but without relying on the likes of Bluetooth or Google ADK? If you also happen to be one of those people who has spare Arduino boards about, you're in luck. Joe Desbonnet combined an Arduino microcontroller with a magnetic coil to create what he calls the "Poor Man's NFC".
The hack allows for a one-direction, low-bandwidth connection between an Arduino board and Android phone (you'll need one that has an electronic compass). Using a one-meter-by-one-centimeter copper cable, the Android app Tricorder, and a 120-ohm resistor, Joe made a coil from all the copper wire, which then connected to the arduino via the resistor on one end. At this point a diode may come in useful to save the arduino from a possible EMK kick, but not essential.
Once locating the magnetometer on the phone and using Tricorder to do a little bit of coding, you would then attach the coil. To get data transfering at a decent rate, you'll need to do a little bit of signal bit banging and Android decodin. Once that's sorted, transfering with data rates of around 7bps is perfectly achievable.
Ok, it's a pretty basic wireless hack, and 7bps isn't a great data-transfer rate (needless to say), but it's a cool way of networking on the cheap, even if it's just for fun. Joe is still trying to tweak the project, so hopefully it will continue to improve. Check out the video below of the hack running smoothly or visit Joe's blog to get all the instructions, coding and explanatory graphs to try this for yourself.
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For comprehensive coverage of the Android ecosystem, visit Greenbot.com.