Mobile application to control metronome

Matej Lenarčič (2013) Mobile application to control metronome. EngD thesis.

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Abstract

When playing musical instrument, especially drumkit, it is very important that tempo is accurate. In order to improve playing accuracy, musicians use device called metronome, which provides constant time, depending on desired beats per minute (BPM). In this thesis, we developed metronome on Android platform and external unit, which is connected with mobile device using USB interface and enables us to control Android device externally. In the beginning, methods and tools used in this thesis are described, following by description of external unit, its components and circuit diagram. Communication between Android and external unit via IOIO protocol is also described here. To transfer data between devices, ADB (Android Debug Bridge) and OpenAccessory protocols are used, depending on Android device support. Then we describe how to provide very accurate metronome based on cyclical playing of a sound clip in PCM (Pulse Code Modulation) format. Using builtin AudioTrack methods, we can cut the previously recorded click according to specified beats per minute and play it in an infinite loop. Application, developed in this thesis, also enables us to tap tempo to easily determine how many beats per minute we actually need. In the end, we describe practical use of this product and also some key user interface components are described. Finally there is a description of possible improvements including using Bluetooth wireless technology.

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