A simple combination lock with Android and Arduino.  The fancy wheel scroller is based on the android-wheel widget from yuri kanivets.

For additional background information on interfacing Android with the real world, check out my other introductory tutorials:

Simple Digital Input

Simple Digital Output

Simple Analog Input

Simple Analog Output

Hardware

Parts needed:

  • Android Device (1.6+)

  • Hobby servo

  • Breadboard

  • Power supply

  • Hook-up wire

  • Android ADK Board*

  • – OR –

  • Arduino compatible and USB Host shield

*Supported boards include:

Google ADK boardFreeduino ADK board Seeed Studio ADK board, and DIY Drones ADK board

Assembly

Simply connect the black line to ground, the red line to +5v, and the yellow signal line to Arduino pin 5 (or other PWM capable pin, usually marked with a ~ symbol). Here is a diagram of the completed circuit (created with Fritzing):

adb_combination_lock

Software

Arduino Firmware

Next, upload the Arduino sketch to the microcontroller. The sketch uses the Microbridge implementation by Niels Brouwers. Microbridge uses Android Debug Bridge (ABD) forwarding over TCP, rather than the official Google Android ADK. You can checkout the source for the Arduino sketch from Github, or just copy and paste the following into the Arduino IDE.

Android App

Finally, install the Android Demo application onto the device. You can either download the pre-built .apkor checkout the source from Github:

git clone git://github.com/mitchtech/android_adb_combination_lock.git

Finally upload the app to the device (or browse to this page on the device and download the apk above). Connect the Android device to the USB Host board/shield, and start up the app.


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