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[lcdproc] Question: How to connect an LED to GPO of Matrix Orbital.

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  • From: wwf AT (William W. Ferrell)
  • Subject: [lcdproc] Question: How to connect an LED to GPO of Matrix Orbital.
  • Date: Mon, 18 Sep 2000 20:35:47 -0600

* David Glaude
(dglaude AT's
mailer blew these chunks:
> Anybody can help use on connecting an LED to a GPO (basicaly 5V output).
> >| Don't forget those GPO(?) General Purpose Output that you have on the
> Matrix
> >| Orbital.
> >| If you find a place to graphicaly show virtual LED,
> >| then we could test GPO without having to actualy distroy LED
> >| (I am very good at doing this and very bad at soldering job).
> >
> >Are those pins just for LEDs? I saw them mentioned in the manual, but I
> >wasn't sure what you can and can't solder onto them. If they're just for
> >LEDs, then sure, how hard can it be? :)
> Well, If I remember well, you have a 5V(?) output on those 6(?) GPO.
> Now if you connect directly your LED to those pin, you might distroy them.
> You may need a resitance in between.

I thought an LED could handle 5V. Then again, last time they let me have
a soldering iron I made some magic smoke with it :)

> But I want to make sure everybody on the list understand that
> Matrix Orbital is NOT a defacto standard.
> It just happend to be the first LCD ever supported by LCDproc,
> the one I have, the one you have, ...

This is true. In fact I smoked the last MtxOrb display I had
(put on that motherfscking connector backwards, *again* :), so now
there's a Crystal Fontz in my beastie.

> Cristal do as good (I think) and you need to compare the price/feature too.

Yes, all they don't have is keypad input. They one-up MtxOrb in the
adjustable-backlight department.

> PS: Rob Hansen once suggested on the list to use an LED rather than the
> heartbeat.

This would work just fine, but not all MtxOrb displays have the GPO if I
recall and like you mentioned above they're not the only LCD maker out
there. Besides, the whole reason I started writing LCDproc in the first
place was 'cause I wanted a damned blinking heart symbol on my computer
like HP's Firehawk workstations did ;) At least in this version I'm
including an option to turn off the heartbeat ;)

I have to say right now the "favored" displays are the Crystal Fontz,
mostly because they're cheaper. Remember you can buy one of their 20x4
displays with a reflective (non-lit) backing for $45.70 (+S&H), and the
backlit ones for $60.20. And that's if you're buying one. I was
impressed to see they've got bulk pricing (making them much cheaper for
companies to integrate into PCs ;)

As I dig into pricing for the MtxOrb displays, I see $74.00 for a
backlit 20x4 without keypad support, and $97.00 for one with the
keypad support. If you've got $138.00 to spend, you can buy a 40x4 with
AT keyboard support (*drool*, expensive but cool). VFDs start at $134.00.

If you can live without LCD-supported inputs, Crystal Fontz are the
better way to go. The MtxOrb displays *are* still pretty good, and if
you need keypad support (or keyboard support), they're so far the only
way to go, unless there's some other LCD makers out there hiding and
waiting for the right moment to pounce on this unsuspecting list :)

William W. Ferrell, System Administrator, Global Crossing Ltd.
950 17th St Ste 2200, Denver, CO 80202 1.303.223.0564

Public key available:
gpg --keyserver --recv-key 7478FC7A

Drop the vase and it will become a Ming of the past.
-- The Adventurer

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