Computer Matrix Board

[GregO]

Jon,
When this forum was at Parallax, you refered to a LED light project that resembled an computer readout board from 1960's Sci-Fi movies and TV.  A Matrix that the lights blinked randomly.  I have need of som info on this nif it is still available.
Thanks!
GregO

[JonnyMac]

The IT guy at Parallax trashed the Parallax EFX boards without giving us a copy -- darned irritating, but dealing with the guy always was.... 

Have a look at the Charlie-plexing thread I posted here:

http://www.efx-tek.com/php/smf/index.php?topic=201.0

By calling the patterns randomly and quickly you can have a much bigger display (of LEDs).  You can also use the SOUND cmd to add a bit of interest to it.  How big do you want your matrix?  With six pins you could have 30 LEDs giving a 6 x 5 array of LEDs.  And as only one is on at a given time, you can run a bit of current through them for brightness.

[GregO]

A 6x5 would be good to start, When wiring this it would be the same as for the faux candles, just with out the capacitor, correct?
Thanks!
GregO

[GregO]

I would not need the trigger at this time, just want it to run continuosly.
Thanks!
GregO

[JonnyMac]

There is a schematic attached to the Charlie-plexing post -- wiring is actually a bit tricky due to the nature of the process.  I'm on my way out but will stop and get a bunch of LEDs to wire a 6x5 array to show everyone what that's like.

[GregO]

Jon,
You are the greatest!
GregO

[randyaz]

Hey Mr. Peabody, I wonder if the wayback machine can take us back to 10/24/2005?  There was a post on the Parallax Forum I'd like to check out.

Well Sherman...we'll just have to try and see...

http://web.archive.org/web/20060217204643/forums.parallax.com/forums/default.aspx?f=22&m=92995

[GregO]

Mr. Peabody is way cool!  Sherman too!
Thanks!

GregO

[GregO]

Yawn!
Up til past midnight wiring and soldering the LED's according to the schematic (lots and lots of connections).  Got up early this morning attached the pot and trigger, change the ULN to the 2003, uploaded your program, flipped the swich and NOTHING!  What have I missed?  I am using 12 volts but none of that seems to be getting to the LED's.  I guess there must be a way to wire the power to the LED's that is not covered in the schematic?  Do I need more juice?  (Not ready to try that out without some confirmation, I don't have time to redo what I have done).

HELP!

GregO

[JonnyMac]

Did you connect the outputs to the Px.W terminals?  If you connected them to the OUTx terminals it will never work, as that circuit requires +5 volts and ground to be organized such that different LEDs can be selected.

[GregO]

Jon!
Thanks for the call and straightening me out.  I'll put it together as soon as I get it back and let you know how it works.

Thanks again!
GregO

[GregO]

Jon,
Here is the latest as I understand it.  The guy loved the demo.  Hurray!  I'll pick that up in the morning and fix it after work tomorrow.  But as I understand it now he wants 4 boards total ---2 with the 30 LED's and 2 half the size.  This is what I gleaned from the phone conversation I had with them earlier.  He has some issues with the color of the LED's on the demo board, so I'll have to build 4 new boards.  The long and the short of it is---I'll get the details in the morning.  Just thought you'd like an update.

Thanks!
GregO

[JonnyMac]

Congrats, Greg!  Remember to wire the new boards to the Px terminals so that you have proper control of the LEDs.  Since two pins are open you can add a trigger and also a speed control using the POT instruction.  Here's the schematic for the Prop-Pot:

[GregO]

Morning Jon,
Picked the demo unit up this morning and had a few minutes to make the connection adjustments.  The speed control works and most of the LED's light up, some more that one at a time, a few not at all.  My assumption is the the ULN2003 is damaged (no smoke, but got very hot) because of the demo hook up that I finagled out of it.  I will replace the ULN this evening at home and hope that takes care of it--I'll let you know.  Then it's off to the races to create 2 control panels.  Thanks again for the help!

GregO

[JonnyMac]

If you put another ULN into the same circuit it will break too....

Patient: It hurts when I do this.
Doctor: Don't do that.