Android + IOIO + Dual Analog Input

  

Dual analog input with Android and IOIO.  This article will demonstrate a basic dual analog Android USB (or Bluetooth) analog input device.  You guessed it… the Etch-a-Sketch is coming soon!

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

Android + IOIO + Simple Digital Output
Android + IOIO + Simple Digital Input
Android + IOIO + Simple Analog Output
Android + IOIO + Simple Analog Input

Background on Android development, IOIO, and electronics:

Meet IOIO
IOIO for Android Beginners Guide
IOIO Wiki
Android Developer’s Guide

 

Hardware

Parts needed:

  • Android Device (1.6+, 2.1 for Bluetooth)
  • IOIO (available at Sparkfun)
  • 2x Rotary potentiometer
  • Breadboard
  • Power supply
  • Hook-up wire

 

Assembly

Connect one side of the potentiometer to +3.3V, the opposite side to GND, and the center wiper to the desired analog input pin on the IOIO. The example uses pins 34 and 35, but can be used with other pins that support analog input (pins 31 – 46 on the IOIO). Here is a diagram of the completed circuit (created with Fritzing):

 

Software

Get the source

With the circuit assembled, the next step is to get the demo application on the Android device. You can either download the pre-built .apk or checkout the source from Github:

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

If you are building from source, you will also need to import the IOIO Library project, and optionally the IOIO Bluetooth library projects, both available here:

git clone git://github.com/ytai/ioio.git

 

Install, connect, profit!

Finally, upload the app to the Android device (or browse to this page on the device and download the apk above). Connect the device to the IOIO, and start up the app.

 

2 Comments

  1. Hello, thanks a lot for this demonstration !
    I’m really interested in doing something like this, getting two audio signals and using one input to send them to my mobile phone via the audio line-in. So it would basically looks like :
    LEFT CHANNEL ———-\____IOIO_______ AUDIO LINE-IN MOBILE PHONE
    RIGHT CHANNEL———/
    The aim is to use the mobile phone for signal processing on two signals in the same time.
    Concerning the hardware, does the audio line-in of a mobile phone (in my case, HTC Wildfire S) allow us to process stereo recording ? I thought it was only mono recording but seeing this, I’m guessing that it could be stereo… I don’t know how to find this information.
    Thanks in advance, any help is welcome !

  2. Hi, that looks really nice!
    Is there a way to store the input values in a file or use them instantly in another app?
    Thanks!

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