This is a cool looking Bubble Display Project. Who doesn’t want to play an instrument that is connected to bubble making system! I think there would be a lot more piano players out there if this was hooked up to pianos in schools. 🙂
“The board was built to support up to 64 outputs. Each output had an LED. It was a simple design of several I/O expanders on an I2C bus. Each I/O expander output was connected to a darlington transistor array (ULN2803A IC) The bus would be driven using an Arduino microcontroller. The board was designed and built with millisecond timing resolution in mind. The Arduino wasn’t able to drive the I2C bus fast enough for 50 microsecond timing resolution on the outputs that we later required.”