Re: Controlling Holiday Lights

["Robert L Bass" <robertbass1@xxxxxxxxxxx>]

> I'm wanting the hardware to control TRIAC
> or SSR switches...

Doable with MIDI, DMX-512, 0-10VDC and a few dozen other means.

> eg a parallel binary I/O port.  With that I
> can turn on and off a light (or anything
> else) at a rate over 1000 times per second.

Considering the lag time between turning on the power and the filament heating up enough to be seen, why would you care if it can do
1,000 cycles per second?

> This allows all kinds of creative fades to
> On, Off, or anywhere in between at 100%
> the whim of my self-written software.

Yep.  I've designed and installed a number of theatrical lighting control systems which would make most home holiday displays pale
by comparison.  I can also tell you that there are existing, off-the-shelf solutions which can accomplish what you want to do,
although none issue 1,000 commands per second.

> MIDI cannot do that and was never intended
> to do that.  MIDI is a control protocol which
> is used to tell my hardware what to do.  I'm
> not interested in another protocol that will
> tell my hardware what to do.  I am trying to
> build hardware.  :)

Sounds like a fun project.  I hope you'll share your experiences as it progresses.

>> The MIDI protocol isn't inherently slow and the MIDI hardware
>
> MIDI is inherently slow.
>
> MIDI runs at several bytes per second.  Each command is a few dozen
> bytes.  Do the math.  It's slow.

You've decided to use another protocol so this is just a discussion -- not me trying to convince you what to use.  That said, here's
some info about MIDI.  The protocol allows an instrument (or sequencer) to be controlled by "clocks" or "ticks".  48 clocks are sent
per second.  Ticks, on the other hand, are sent at a rate of 1 message every 10 mSec.  That's only 100 changes per second.  Note
that a "change" can be a command such as "Begin fade from scene 125 to 126" or simply, "turn circuit 125 on".  Note that while ticks
are intended as a means of keeping things sync'd, it is possible to store a series of commands to build a sequence, then cause them
to execute in order based on tick count.

> Thanks for your offer, but it is the wrong direction for me.

No problem.  I look forward to reading about your project (hoping you'll hang around and share what you learn as you go).
Regardless how you choose to execute it, this is the kind of project that interests a lot of regulars here.  IN that light, you
might also want to Google the archives of CHA using "Christmas lights" or some such.  There have been a number of interesting
threads on the subject every year since I've been posting (and that's a long time) here.

Best of luck.

--

Regards,
Robert L Bass

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