Actions
Forum Thread Details
  • State Suggested Answer
  • Replies 6 replies
  • Answers 3 answers
  • Subscribers 557 subscribers
  • Views 1405 views
  • Users 0 members are here
Related

FPGA PWM LED driver DMX pixel mapping and Video input simultaneously?

m-viking{}

Hey everyone, I'm pretty new to FPGAs but i have programmed a few arduinos for little art install projects to drive neopixels. But I wanted to take my design fun to an entirely different level.

 

I have dreams of developing an LED PWM controller/driver to a display of any size given that the amount of RAM provided can support thousands of LEDs.  I want to be able to control the input in real time perhaps using a DMX lighting program like QLC+ or any visual program, VDMX, Resolume etc. which can output video content to the display. All data sent to the pixels via ethernet cat 5 cable. Although I think the physical driver itself would be separate from the pixels themselves in terms of a modular system. Like the power, and scalar are separate from the LED panels themselves which would most likely contain the DAC PWM drivers to physically drive the voltages to the RGB(W) LEDs.

 

If there is a way to be able to drive the pixels using both lighting and video platforms simultaneously? Basically have a central hub that is handling the input from the computer programs for DMX pixel updates and the video input from visual software. Also scaling it to however many LED's are there and what resolution.

 

I don't know much about how it could be designed but with FPGAs I feel as if anything is literally possible. Hoping to hear from someone about this who has tried to build something similar or who has built drivers. Any problems they ran into or if this is even possible in terms of the input of digital video signals passing through a scalar that drives a video screen. except that screen is a series of LED pixels that have individual addressable PWM drivers. and then interfacing an ethernet connection to the input device taking in the DMX lighting information. or take in SDI/DVI/HDMI video signals. Then sending all that information that the addressable PWM drivers that are taking data in from an ethernet cable.

 

I hope it isn't too far out there to have both lighting pixel mapping AND video input running simultaneously, i have seen just the video input case done on shows I have installed with Chinese manufactured LED walls that take video input to a scalar and has a ethernet cable home-run snake with 5 ethernet data outputs and "snaking" the data along the panels. The entire wall was separated in to 5 sections that would take data input from the home-run and "snake the data" along to a certain number of panels. if you can imagine it was probably over 10,000 LEDs if i had to guess running a 200amp dedicated circuit for the whole wall (im fudging numbers but it was a decent scale production). But I am thinking maybe a little smaller scale possibly 1,000 RGB LEDs.

 

Sorry for the long post had a thought in my head for a couple of years I am happy I found a community that will have maybe a little feedback! If I don't make any sense at all let me know! Or if you understand what I'm trying to do I would love to hear from you if you have any suggestions how to start with the programming, and what Dev board is suitable for this situation etc.

 

Cheers!! image

  • 0

    Like this?

  • 0 in reply to clem57

    Hey Clem! Thanks for responding!

     

    Yes!! in the matter of using the ethernet to transmit what needs to be displayed. This is very similar to what I am talking about!

  • 0 in reply to m-viking{}

    Some random thoughts:

     

    If you want to build large (and variably sized) arrays of LEDs you'll need some kind of modular system. The central controller won't do the PWM (if that is the control technique used) for the complete array. A rational scheme would be to build smallish panels, maybe 1000 RGB leds in each, with its own controller, power conversion and Ethernet interface. If you want a 60Hz update rate and 256 levels that's about 180kbytes per second but the power is a of the order of  600 W (100mA per led, 2V). You would need about 110 row and col drivers so a low to mid range FPGA could do the precision timing, control and Ethernet interface.

     

    The central controller will need to address many panels, Ethernet will hold up OK for up to perhaps 250 panels (Gb Ethernet 50% load). The 150kW power will be more of  a problem than the cost of the controller.

     

    If you only have 1000 leds altogether that only makes a 32 x 32 array which doesn't really get started on video - even pathetic VGA resolution is 640 x 480 = 307200.

     

    The power handling problems with big LED arrays are far more of an issue than the image control electronics, for  a home made system you can scale down the power, perhaps to as little as 50mW per led.

     

    MK

  • 0 in reply to michaelkellett

    Hey MK,

     

    Thanks for responding that does help. From what you're saying it seems an FPGA could do all of the above. So the panel itself is containing all the circuitry to receive data for the addressing and passing along to other panels. so the row and column drivers have to do all the PWM if I am not mistaken. This may be way over my head but I am willing to take the challenge! I hope I am in the ball park with this one.

  • 0 in reply to m-viking{}

    Not exactly, every panel would have it's own Ethernet interface, they only need connect to a central controller and have no need to pass any information on. That way all the panels are identical, don't contain any redundant circuitry, and the array of panels can easily be expanded.

     

    If you haven't ever done any FPGA work this is a very ambitious first project - try something simple first like a 10 x 10 panel.

     

    MK