MINI MIDI MONITOR

MMM

This page is set up in conjunction with an article published the March and April, 2001 issues of NUTS & VOLTS magazine. Source coding not included in the article can be obtained here at no cost.

If you use RS-232 or Musical Instrument Digital Interface (MIDI) data links, this project will give you a useful addition to your toolkit that has not been available in the past. The MINI MIDI MONITOR (MMM) can accept RS-232 or MIDI data and display the data in hexadecimal or interpreted format. There is a MIDI option to filter out MIDI active sensing status bytes. I have not been able to find such a dual-purpose device available in the commercial world, so I decided to build one from scratch - and you can too!

The goals of this project are to build a device that will:

1. Decode MIDI serial data and display MIDI messages in plain English
2. Do double duty as a high speed ASCII display
3. Have IN and OUT connectors so it can sit invisibly and monitor data between any data source and sink.
4. Cost less than $50 to build.
5. Have a large readout for those 1960 musicians who now wear bi-focals.
6. Run on battery or 5 volt power supply.

MMM recognizes many types of MIDI commands. An example of the interpreted MIDI output is given in the figure above. The message displayed is a "note on" command on channel #1 for an octave 4 A# with a velocity of 64. With a simple change of the switch settings, you are ready to display ASCII data. Free software is available to program your own 16F873 PIC or you can buy a preprogrammed chip here for $20 (A 20% price reduction).