1. Laser Harp
Team:
Peter Crinklaw
Qiushi Jiang
Edwin Rodriguez

2. 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

3. Demo Official website for our Laser Harp

4. 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

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

6. 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

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

8. DESIGN - OVERVIEW

9. 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

10. 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:

11. 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

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

13. Design - synthesizer
Low frequency signal:
High frequency signal:

14. Design - Synthesizer
Just stores one audio signal

15. 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

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

17. Questions