[vcf-midatlantic] Any MIDI enthusiasts around?

☼ wil lindsay ☼ wm.lindsay at gmail.com
Sun Mar 13 20:00:41 UTC 2022

Using an Arduino as a gate with some 6N138 optocouplers would allow you to
translate the signal from Midi to something like the
https://github.com/FastLED   Arduino-WS2810 libraries should be
fairly simple, give or take figuring out the power supplies for your midi
bridge and the LEDs.

The only real issue in using MIDI would be the lack of match in the specs.
Midi is built around 0-127 (#0-#7F) where these LED libraries are typically
0-255 for each color. I'm sure you could sort something on the arduino like
The Note (0-127) is an addressable LED and the Velocity 0-127 (doubled) is
the color, where notes would be expected in a series of three. (R,G, & B).

Midi also uses the irritating speed of 31,250baud which normally has to be
a cludge on an arduino. It might make more sense to just use serial at a
higher speed and define your own information packets. The SPI speed of
these LED strips is lightyears faster, and your  arduino code and/or the
library will typically collect your color commands in a buffer and send
them a bit delayed. There's a little bit of lag, but even if you're
synching to music, the human brain has an amazing tendency to make light
flashing timing "feel" right, even when it's off.

On Sun, Mar 13, 2022 at 2:59 PM RETRO Innovations via vcf-midatlantic <
vcf-midatlantic at lists.vcfed.org> wrote:

> I am looking to control some RGBW leds (maybe SPI-based strips, maybe
> individual high power RGBW LEDs, not sure yet) with some of my classic
> computers.
> That's pretty easy, no concerns there.  Lots of arduino projects or I
> can just add in a 6522/6821/etc.
> But, I thought, instead of just making a hobby project, I should try to
> design something that would work with classic systems *AND* current
> gear, and not be so platform dependent.
> MIDI came to mind, both because the cost to interface is pretty low,
> cables are cheap, and MIDI is very well supported.
> Where I am struggling is getting a handle on how to map the ability to
> set an individual LED color in a strip of say 20 or 60 to the MIDI
> protocol without just punting and using SysEx msgs. And, I might have a
> bunch of these strips (more than 16 perhaps, though my initial project
> only needs 10-12.
> I am also aware of DMX lighting and MIDI->DMX converters.  DMX XLR-5
> cabling is a bit pricier than MIDI 5 pin DIN (though the RS485 protocol
> seems simple enough), so I thought maybe I should just emulate a
> MIDI->DMX->LEDs in my design.
> Anyone familiar with MIDI-controlled lighting and how it's mapped to
> MIDI messages?
> Jim
> --
> RETRO Innovations, Contemporary Gear for Classic Systems
> www.go4retro.com
> store.go4retro.com

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