A simple android app to write/read data to/from arduino.
Android Download and setup Android Studio. Create a new project and add these project files to their correct places. Follow the notes in android/notes.txt file. Build the project and upload the .apk to the phone, start the app.
Arduino Download and setup arduino IDE. Make sure the connection to arduino works. Compile arduino/main.cpp file on Arduino IDE and upload the software to the device.