1. ECE 492 - Computer Engineering Design Project
Laser Harp
Qiushi Jiang, Edwin Rodriguez, Peter Crinklaw
2015
What is it?
It’s a harp with lasers for strings.
Block the lasers to play music.
Synthesizer
The synthesizer’s job is to take commands such as “Play F Sharp” from the MIDI Generator, and output an audio signal (as seen below). Since it can’t store an audio signal for every possible note it can play, it instead samples from a single audio signal at a particular rate corresponding to the pitch of the note. The faster the rate, the higher the pitch. The audio output is sent to the built-in line-out port which can be connected to standard 1/8” audio jack.
Features
Generates sound using a full-range synthesizer
The laser harp has a MIDI output that can be connected to other synthesizers
Supports multiple music scales
Allows for key transpose
Components
DE2 x1 : The brain of the laser harp
Laser diode x 8 : The laser “strings”
Photo diode x 8 : Laser sensor
MIDI Output x 1 : External MIDI interface
MIDI Generator
Software running on the DE2 board detects when a laser is blocked. It determines which laser is triggered and generates a MIDI signal according to the music scale inside the software driver. It sends this signal to two components: our own synthesizer, and the external MIDI output port. A MIDI signal only specifies the pitch of the note, not how it should sound. So external synthesizers plugged into the harp’s MIDI port can interpret the MIDI signal however they want, emulating any kind of instrument.
Sine wave audio signal
For colour ideas, University Visual Identity Guidelines can be found here:
Laser Harp in action
MIDI Signal, saying “start playing C4”
System Overview
Department of Electrical & Computer Engineering