Senior Project Electrical Engineering 2012 Digi Tap Designing

Senior Project • Electrical Engineering • 2012 Digi. Tap: Designing and Creating MIDI Compatible Tap Dancing Shoes Jacob La. Rocca Advisors: James Hedrick, Palma Catravas Hardware Sensors A 2 mm deep channel was milled in each aluminum tap to fit a 3. 5 mm diameter piezo disc. Detection The pulse shown below is the voltage reading from lightly tapping one of the outfitted taps on the table. The voltages could reach up to 80 volts on a hard tap, and any tap produced a voltage too high for the microcontroller. In order to compensate for Filtering and Stretching this, I created • Schottky Diodes were used in the clamping circuit filtering and pulse • An RC filter circuit smoothed out all of the ripples stretching circuits • Monostable 555 timers were used on each pulse for each tap. to create a square pulse 2 ms long Microcontroller and Radio • An m. Bed microcontroller was used for its speed, size, and built-in MIDI library • Much easier to program because it doesn’t use a proprietary language • Xbee radios were used, based on their size, compatibility, and range Hardware Setup Software • • Programmed in C Used a pre-written MIDI library provided by mbed. org Important Functions and Libraries Interrupt. In: Instead of using a Digital. In input pin that reads 1 or 0, this function looks for a rising edge, allowing for more accurate and detection quickly, with less false triggers USBMIDI: The USBMIDI library is coded to transmit standard sets of 8 -bit MIDI signals. Some of the signals include Note. On, Note. Off, Pitch, and Aftertouch. Code Process The Xbee radio is monitoring continuously at 57600 baud, and reads in single ASCII characters. If the message is ‘A’, ‘B’, ‘C’, or ‘D’, then the m. Bed sends a MIDI signal to the computer. If the Xbee reads ‘W’, ‘X’, ’Y’, or ‘Z’, the m. Bed adds 1 to the note values assigned to each tap.