Step 1: You need:
or search for "bluetooth module" on ebay
I've bought mine for $8.20 on dealextreme.
2. An Android device with bluetooth.
3. An Arduino board.
4. Some sensor or potentiometer to read values from.
Step 2: Setup the Arduino hardware
Device name: linvor
Baud rate: 9600
You can leave the settings as they are or change them with a serial adapter.
For more info see: http://wiki.openpilot.org/display/Doc/Serial+Bluetooth+Telemetry
Connect the bluetooth module to your Arduino.
BT module Rx-> Arduino Tx
BT module Tx-> Arduino Rx
VCC to 5v
GND to GND
Connect a sensor or potentiometer to analog pin A0.
Upload this sketch to your Arduino: http://pastebin.com/raw.php?i=xmyr840j
The onboard LED at D13 is toggled everytime a sensor value is requested from the Arduino.
Step 3: Setup the Android device
(This instructable is based on SL4A r4)
Copy the code from http://pastebin.com/raw.php?i=FVxKzf1g
and name it androino.html
Copy the code from http://pastebin.com/raw.php?i=XEmEsATU
and name it androino.py
Change the BT_DEVICE_ID in androino.py to the address of your BT module.
If set to None, Android will ask you at program start which bluetooth device to use.
Upload both files to the /sdcard/sl4a/scripts/ directory on your phone.