DIGITAP: Designing and Creating MIDI Tap Dancing Shoes

1. DIGITAP:Designing and Creating MIDI Tap Dancing Shoes Jacob LaRocca Advised by James Hedrick and Palma Catravas

2. Design Requirements • Must trigger consistently and accurately with little delay • Must be able to send the data from the tap pack to the computer wirelessly • Must be easily programmed and interfaced

3. The Design Proccess • mBed based system • Sensors • Analog In • Clamping circuit • Digital In • 555 timer circuit • Communication • Through XBee Radio • Serial Port • Long USB cord • Alternate mBed at computer • Arduino based system • Sensors • FSRs • Piezos • Analog In • Digital In • Communication • Through XBee Radio • Serial Port • Long USB cord

4. PROBLEM #1: PIEZO OUTPUT • Each tap is fitted with a piezo sensor in between the tap and the shoe. • The piezos create large voltages, upwards of 60 volts, much too big for the microcontroller’s A/D converter • The voltages produced by the piezo are nearly impulses, and bounce back and forth with multiple peaks

5. Solution: Signal Filter And 555 Timer Circuit • Using Schottky diodes, signal diodes, and an RC filter, the pulse was shaped to a consistent pulse that decayed over the time span of 10 ms. • Once the pulse had been shaped, a 555 timer circuit was designed to trigger on the rise and hold the signal for about 2 ms.

6. CURRENT HARDWARE SETUP

7. Computer mbed, main(){

8. Current State • Currently working with a Mark XV prototype • 519th variation in coding • Sensors are glued in place in milled channels • Connectors on the shoes are reliable and sturdy • Battery power is still an issue

9. Future Work • Create an easy to use software interface for the MIDI programming • Use the chaotic curves of accelerometer data to produce music • Choreograph a dance that creates a song • Patent “DIGItap”

10. Acknowledgements • James Hedrick • Gene Davison • Palma Catravas • Mbed.org(all members of the forums) • Arduino.com (all members of the forums) • Calder Phillips-Grafflin • Zak Smolen