Using Vixen To Drive Tri-Color LED Matrix

[bcgary]

Hi;
I am brand new to this so I admit that I am jumping way ahead of my experience in asking this question, but is it possible to program Vixen to control a 16 X 16 LED matrix using a tri-color LED (i.e. a three color LED with a common cathode, so you would have 16 rows of common cathodes to control and instead of 48 columns of LED's you would have 16 columns X 3 anodes each for a total of 48). This arrangement would give you the ability to generate multi-colored displays.

I have the required tri-color LED's but before I spend my time wiring them up I thought I'd ask the gurus.

Any thoughts, comments or cautions would be greatly appreciated.

Cheers;

BCGary

[RJ]

Not in an easy way. Could it be done? Yes but it would require a lot of work on your part for programming vixen to make it look like you want. You would have to use three ledtriks boards. Make sure you adjust current correctly so you do not burn out the leds as they most likely will not handle what we are sending to the ones on the ledtriks. Then to program you would need to program every frame three times on different panels like you are doing three color silk screening. one with just the reds and then one with just the blues and then one for the greens. set each controller to a different board number to match the correct color connected. Its just that easy! :twisted: what a pain.

Or wait.

I am working on a full color Ledtriks which would do any color not just three and it is in the works. I can do it now but keeping the cost reasonable takes a little more work in the design phase. Plus I would like to reduce the work load to build it. I hear the agreeing in the distance!

We shall see but right now... Its setup time for xmas. :shock:

[NogginBoink]

Gary,

With enough effort, Vixen can probably control just about anything. KC has made the plug-in architecture exensible, so if you can't find a hardware protocol you can adapt to your needs, you can write a new one.

Now... if you want to control a single three-color LED, that's trivial. If you want to make a LedTriks panel with three color LEDs to get any color of the rainbow, that'll take some engineering effort.

The "pixel" project mentioned elsewhere on the boards is an already baked solution to making one point of light any color you want (kind of like a three color LED on steroids). But again, doing the same for a LedTriks panel would take some thinking.

(If I had to bet, I'd say we'll have a design this time next year.)

-Matt

[bcgary]

RJ & Noggin:

Thx for the quick reply to a noob like me!

I think I have found my calling...I have ordered 2 LEDTRIK boards from John, samples from Allegro, still need to buy red LED's from Hong Kong...hoping to get something up and running for this holiday season.

If I try the tri-color version described in my original post I will let you know how it goes.

RJ...let me know if I can help with the color version application...I'd like to try and contribute.

BCGary

[grages]

Plus I would like to reduce the work load to build it. I hear the agreeing in the distance!


:D :D :D

[bcgary]

BC may be far but we can still hear the distant call for help.... :D

[wingrunr]

RJ, are you using PICs in your tri-color? I have created a PIC-based board that I am testing this year. It reduces the load on the computer a great deal and wouldn't be hard to extend to tri-color LEDs (I think).

[RJ]

If it plays out the way I am working on would use one pic. And be much easier to build. Plus be maybe twenty times as bright. Kinda busy at the moment so I wont be back on it till after xmas.

I have a design I am working with on the bench to plug into the standard Ledtriks to handle all the work and allow serial communication to the Ledtriks which does what you are talking about with one pic. I figure the ones that are already out there would like a cheap way to offload the work. I talked with KC and asked if he would do a plugin for it and he will once the design is proven out.

[AI]

If it plays out the way I am working on would use one pic. And be much easier to build. Plus be maybe twenty times as bright. Kinda busy at the moment so I wont be back on it till after xmas.

I have a design I am working with on the bench to plug into the standard Ledtriks to handle all the work and allow serial communication to the Ledtriks which does what you are talking about with one pic. I figure the ones that are already out there would like a cheap way to offload the work. I talked with KC and asked if he would do a plugin for it and he will once the design is proven out.
I will be looking forward to this. I think the RGB is the way to go. Massive color changes, and am hopeing to find a way to do strings. AI

[Wombat]

this might give you some ideas on how to layout the matrix

http://hypnocube.com/instructions/

the board looks good too if it can be rewritten to do Vixen

Wombat

[P. Short]

The Hypnocube has 64 LEDs, the current LEDtriks has 768. The difficulty (if you can call it that) is to scale up while keeping the clock rates reasonable and keeping the amount of hardware duplication under control.

--

Phil

[RJ]

Yes I don't see it being the way to go but who knows one of you may make it work. After christmas and tear down I will have a chance to work on it while waiting on Lynx coop stuff to come in and if my nutty(as always) idea works out I will show you what I'm up to. I hope to have it a little easy to assemble than a super hypno cube would be. Man I guess we are not the only crazy light people huh?

[P. Short]

Well, if that doesn't pan out I know of a way to do it with a PIC18F2525 (or similar), nine of the 16-bit Allegro/MBI s/r chips and the latch-decoder and anode drivers. The major limitation in my eyes to this approach is that it only supports 32768 colors, and that the (assembly language) code would be relatively opaque.

--

Phil

P.S. Wiring the LEDs will not be easy.

--

Phil

[RJ]

Yeah thats the part I am working on, The circuit is not bad. I was think the same even down to the 18f2525 that I bought to do it but I think we can create something cool for this and get rid of a lot of work.

[P. Short]

The key questions are:

1) how many colors

and

2) what refresh rate

are desired? The scheme that I've come up would provide a refresh rate of 100 Hz (for all 16 scan lines) and 32 levels per color-LED or 32768 colors (32*32*32) altogether. The remaining issue for me is the screen update rate, for which I don't have a number right now (perhaps as low as 6 full updates per second).

--

Phil

[RJ]

My post was confusing. When I say I was thinking I dropped it to look at a new setup that would prehaps be easier and quicker with less cost.

That is the old fall back for me to simply build a Standard ledtriks with RGB leds and do the dimming of the indepentant channel using the cheap method I worked out. It would be 256 * 256 * 256 colors not that we need that many. It's kind of overkill. The refresh rate could be very high on the setup I was using as my base plan. The only reason I am working on another idea is the cost and work involded. its not 768 * 2 connection now its 768 * 4 for a ledtriks in this config. pcb's would help but would raise the price even more.

I truly hope the setup I was currently working on works out as it will really be a hit I think. I just had to stop over the holidays to get my show going and some work around the house done for guess who will be visiting from xmas to new year day. Then I take down lights and I'll fire up the protoboard and the logic analyser again. If it works it should be able to do more than a ledtriks every dreamed of. If it fails I will tell you all about it and you guys can make fun of me. LOL

[NogginBoink]

The key questions are:

1) how many colors

and

2) what refresh rate

are desired? The scheme that I've come up would provide a refresh rate of 100 Hz (for all 16 scan lines) and 32 levels per color-LED or 32768 colors (32*32*32) altogether. The remaining issue for me is the screen update rate, for which I don't have a number right now (perhaps as low as 6 full updates per second).

--

Phil
Refresh rate doesn't have to be anywhere near 100Hz. Movies are at 24 frames per second; I'd think that 24 full refreshes per second should suffice.

The number of colors is an interesting topic... have you considered that with an R, G, and B LED, full on for all three might not be white? You may have to apply a correction curve on one or more of the colors to get the results a user might expect. (Having said that, anyone who demands more than 32K colors is crazy, IMHO.)

[P. Short]

You are usually stationary when you are watching a movie.

Flicker is very noticeable with a 60 Hz 'refresh' rate for half-wave LED strings as you move around. It is also quite conspicuous as you are putting up a half-wave LED string if it is turned on at the time, every little motion of the string produces noticeable flickering. I'm actually worried that 100 Hz may be too low a frequency.

--

Phil

[NogginBoink]

The LedTriks aren't half-wave, though. The LEDs are powered by DC, aren't they?

In any case... I'm sure that even a modestly powered PIC chip can produce an acceptable refresh rate. And if more horsepower is needed, the PIC24 series can go up to 40MHz without any real cost increase.

[P. Short]

No, but the PWM intensity control has a similar effect.

--

Phil

[ben]

let me add in my worthless info.

I would like to have a board that has Green, Red, Blue, and white leds. I already have the board planned out. I figured the easiest way was to just addin a parallel card (or two) and run 4 Ltrix for Green, Red, Blue, and White. Then program each color seperately. This is my one year project. I will start with one Ltrix per color and go from there.

Ben

[tconley]

Is there any update on this??

[RJ]

Not on my end at least,

Some people have keep me busy build the stuff they want. (ext dmx dimmers with 128 ch, cheap DMX dongles so you could feed your families and do blinky with DMX! That kinda stuff

:)

[tconley]

yea yea yea..........LOL

[envisionelec]

Wow, I am not only interested in this design, but am willing to offer some assistance where I can. I am no programmer, but I have extensive PCB layout and "make it cheap and easy to understand" experience.
I can offer things like super-cheap LED board strips that plug into each other for rows/column connection.
I built my first "from scratch" lighting controller in 1988 at the age of 12 and, more recently in 2001 with a DiscoLitez applicaiton. I haven't touched the stuff since...but I want to do a big two-sided "video" screen on my roof. If this is at all a possibility - let's get started!

-Aaron

[scorpia]

i was talking the other day with some others and tossed around the Idea of making some 16x16 led boards.

these boards would have an LED spacing of around the 12-15mm (1/2 inch)

1 with only single color LED's with edge connectors giving them the ability to connect 3 together to make a 16x48 display.

the second board was an RGB version with 16x16 led's that could be driven with the current ledtricks board. if im correct with the current on off arangement it would allow 8 different colors to be displayed. also the possibility of having the same connectors to interconnect them.

with the talk of an RGB controller i would hope that the second board could be upgraded to multicolor with the correct hardware.

does anyone think they might be interesting in a boards like this being made?

Regards

Peter