karl@sugar.hackercorp.com (Karl Lehenbauer) (10/16/89)
How about using a MIDI lighting controller? There's this one by J. L. Cooper that I think outputs the 0-5v standard. It has a bunch of faders and moving them puts out a MIDI stream of continuous controller messages (I guess) which you can record with a regular sequencer and play to the MIDI-in on the box, controlling 16 channels or so per box, multiple boxes were supported. It looked pretty neat when I checked into it a couple years ago. I don't even know if J. L. Cooper is still in business, but if so this is one way to get off the ground with no hardware development whasoever. It'd be a nice thing to support in one's multimedia system, n'est-ce pas? -- -- uunet!sugar!karl "There is hopeful symbolism in the fact that -- flags do not wave in a vacuum." -- Arthur C. Clarke -- Usenet access: (713) 438-5018
ccplumb@rose.waterloo.edu (Colin Plumb) (10/16/89)
In article <4369@sugar.hackercorp.com> karl@sugar.hackercorp.com (Karl Lehenbauer) writes: >How about using a MIDI lighting controller? There's this one by J. L. Cooper >that I think outputs the 0-5v standard. It has a bunch of faders and moving >them puts out a MIDI stream of continuous controller messages (I guess) which >you can record with a regular sequencer and play to the MIDI-in on the box, >controlling 16 channels or so per box, multiple boxes were supported. H'm... the discrete (one wire per dimmer) standard, which isn't used much any more, is 0-10v. A lot of people develped various multiplexed analogue and then digital standards, with Strand winning the analogue market-share wars and getting their standard formalised as AMX192 in 1986. This is 0-5v, but merging multiple streams is tricky so multiple controllers isn't a good solution. The one I was looking at is DMX512, which is also difficult to connect multiple controllers to, and I'm not sure if it's the same thing. 16 channels per box seems awfully limiting. 64 is, I'd think, a reasonable minimum. Also, a quick sanity check... when light levels are changing rapidly, you need at least 15-20 updates/sec. 20 updates/sec x 64 dimmers x 10 bits/update = 12,800 baud, within MIDI's range. But wait! How many bytes does it take over the MIDI port to change a light level? 2 is okay, 3 gives problems... (I hope there's a deeper FIFO in the 3000's serial port.) >It looked pretty neat when I checked into it a couple years ago. I don't >even know if J. L. Cooper is still in business, but if so this is one way >to get off the ground with no hardware development whasoever. A differential driver isn't a heck of a lot of work. There are sample schematics in the DMX512 standard. All you need is +5, -5, one chip and about 3 resistors. -- -Colin