Laser Harp Team: Peter Crinklaw Qiushi Jiang Edwin Rodriguez

What Is A Laser Harp? A laser harp is an instrument composed of laser “strings” Notes are mapped to the laser strings and when a laser is blocked, a note is played

Demo Official website for our Laser Harp http://www.ualberta.ca/~qsjiang/laserharp.html

Motivation The motivation for this project was to create an instrument which is: Great for live performances Easy to play Encourages engineering in a younger audience

CORE Functionality Internal Synthesizer The laser harp offers a built in full-range synthesizer External MIDI output support Produces MIDI 1.0 compatible signals

ADDITIONAL Functionality Able to change music scale on the fly Such as Major, Minor, Blues… Able to shift to any key So you can jam with your favorite sound tracks. Simple user interface

Design - Overview Input and output External MIDI Signal NIOS II Synthesizer Laser harp hardware

DESIGN - OVERVIEW

Design – Laser detection 8 photo diodes Ambient light: 0.2V Laser: 0.5V Comparator circuit implemented using op-amp Threshold voltage: 0.35V 8 GPIO pins generating interrupt

Design – Midi generator Maps lasers to a music scale Generates a MIDI 1.0 signal MIDI signal is basically the digital representation of music notation. Image from: http://online-music-score.com/

Design – Midi generator Signal Contains 3 bytes and 2 bits separator around each byte. 0 Status Byte 1 0 Pitch Byte 1 0 Velocity Byte 1

DESIGN - SYNTHESIZER The synthesizer’s job is to produce audio signals:

Design - synthesizer Low frequency signal: High frequency signal:

Design - Synthesizer Just stores one audio signal

Design - synthesizer Audio Signal sent to the WM8731 Audio Codec Codec converts digital audio signal to analog audio signal Analog signal finally reaches the speakers

Potential improvement Additional sensor to provide note velocity Octave shift Pedal / IR distance sensor More instruments

Questions