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Controlling real world devices using MIDI


Project Notes for use of MIDI to control real world devices (RWD) devices and animitronics for a halloween installment.

In the background page I talk about lessons learned in the first few years. Selecting and installing air cylinders, manifolds, hosing, field wiring, and more. In those ancient times I used a home-built state machine. In 2009 the devices stayed pretty much the same but the state machine was replaced with a midi sequencer.

The main focus of this site is showing the use of inputs to midi devices to control transport, the use of outputs to control real world devices, sound tracks, and the connecting bits of relays, remote controls, and external devices. All of this is controlled from a MIDI sequencer on a PC.

MIDI was explained to me as something akin to a 16 track tape recorder. The basic control occurs with the transport function which consists of rewind, play, fast-forward, stop, record - and more. MIDI also offers looping and markers. There are a number of MIDI sequencer applications but I wound up with an older and simpler DAW: Cubase SX. From what I can see they should all work interchangeably. My suggestion is to use something that is simple and scaled down for these types of projects.

The 2009 project began with a 2' cube jack in the box. A crank is turned by a motor on one side, the lid is controlled with air cylinders, and jack springs from the box when it opens. A is pulled by what I call a "truck" (a 6x18" wooden platform with 4 wheels) which is pulled and pushed with two air cylinders. High quality monitors are used for sound, lights within Jack are 24volt halogen while a separate AC controller operates up to five channels of lights that run on 120V house power.

I looked at several different approaches for controlling RWD (real world devices) and wound up with MIDI - largely on the dare of a friend. I made an important connection with Tom Scarff who designed a custom circuit for my needs.

It's all fine to have 5 volt logic that in theory will switch up or down based on midi signals - but the real trick is getting that to power RWD. The Miduino by itself (all microprocessor boards) will only light an LED. By luck, a friend had given me an Opto22 relay control board. As it turns out this allows the control of both input and output signals because of the modular design.