phi-X is a metronome with a speed trainer. It increases or decreases the speed (in bpm) within a certain range of bars. I’ve built the device with an AVR ATmega8. It has a small speaker, but there’s also the opportunity to use headphones with a 3.5 mm jack socket. Furthermore the metronome has a LCD with an HD44780 controller, a LED that flashes at every beat, two potis to adjust the speed and the meter (from 1/4 to 4/4) and a button for the menu.
The sound output is realized with pulse width modulation. To increase or decrease the speed, the start value for the timer counter is modified linearly in the timer overflow interrupt routine.
The source code, the AVR Studio 5 project and the schematic can be downloaded here:
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