My Lights 'In Action'

"This document describes a project I undertook and discusses
the reasons why I felt that designing and constructing
my own was preferable to buying a commercial unit"

The Hardware

During my investigations of existing lighting control units I was disappointed to find a total lack of imagination and flexibility in the way light channels were controlled. Commercial units only seem to use MIDI Note-On messages to extract the light channel and intensity values.

Create Dynamic Bouncing Effects
Create Dynamic Bouncing Effects

Using this Note-On strategy also prevents the MIDI port from being used to drive other sound modules etc. as notes will sound. I found creating sequences with Note-On data within a sequencer's graphics editor extremely difficult. The commercial units also come with internal preset light sequences which aren't modifiable.

Edit Patterns together to Produce a Sequence
Edit Patterns together to Produce a Sequence

The Hardware

I have implemented a 12 Channel System capable of delivering 300 Watts per channel. A Motorola 68HC11 Microcontroller was used to receive the MIDI messages and write them into an Altera 8254 Field Programmable Gate Array (FPGA) device. This device has a circuit configured within which generates the control triggers for the triac devices. These control the lamps' to give 128 intensity levels.

Graphical Editing of a Pattern
Graphical Editing of Pattern Slur2

MIDI Control

The control of light channel selection and intensities was achieved using Unallocated MIDI Controllers. For example, these messages can be generated by Cubase's MixerMaps, (using faders) List or Key Graphics Editor. The result is light sequences or patterns that can be saved for insertion into musical arrangements later. The patterns can then be trimmed in length, or compressed in time etc. - basically any manipulation the sequencer's editor(s) allow.

Graphical Editing using Faders
Graphical Editing using Faders

Light Level Control

Each light channel has 3 MIDI Controllers that affect it.

Channel Level

is used to generate the patterns as described above. The full 0 to 127 value range is used but as we will see later (in Master Gain) the 127 value doesn't necessarily mean full brightness.

Pattern Slur2
Pattern Slur2

Channel Gain Master Gain The lights are accentuated on the 3rd beat of the bar.

A Future Product

For upward compatibility the Note-On message strategy would also be incorporated as well as my Channel Level Controllers method. Using an FPGA device reduces the overall component count and costs. They can be used to expand the number of channels by plugging in larger capacity devices into the same socket.

Be Creative - Map Drum Rhythms to Lights
Be Creative - Map Drum Rhythms to Lights

Having lots of low power light channels enables much more creative, complex and dynamic effects to be produced. Lighting rigs are expensive, but by using ordinary 100 Watt Spot Lights, a large array can be constructed cheaply.

User Applications

Cross Patterns...
Cross Patterns...

The $64,000 Question:-
Does this prototype have
any Market Potential?

A summary of the facts:-

Please contact me if you have any questions, comments or require more information.

Harvey Twyman,
Digital Systems Laboratory,
Department of Electronics,
University of Kent.
Kent. CT2 7NT

Tel: 01227 823198