Pixel Strobe Controller

David_AVD

David_AVD

Grandpa Elf
Community project designer
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Jun 12, 2010
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Earlier today, there was some discussion about using WS2811 chips as a basis for a pixel strobe.

The general consensus has been that DMX (either conventional or as E1.31) is too limiting to achieve a strobe effect by itself due to the data refresh rate.

So, we're back to thinking about a pixel strobe controller again. Such a controller would drive the pixel strobes and take it's input from a DMX stream.

It could have various parameters such as:
  • Brightness - you might not always want to flash at 100% intensity
  • Rate - how often the strobes flash
  • Duration - how long each flash lasts for
  • Fill - how many strobes flash at once
You could set these parameters before the strobe event (while they are dark) via a few DMX channels, then use another channel to turn them on/off. Perhaps the brightness channel can serve as that function.

I'd envisage a board with DC input, DMX input and pixel output connectors. It would also have a DMX address DIP switch. Pixel type (6803 / 2801 / 2811) could be selectable via jumpers.

Anyway, that's my guess on a starting point.
 
i still would like to see strobing options added to normal e1.31 controllers as a use of one of the extra two channels that is wasted in every univers
 
I have started the board design for the strobe controller. Just a few parts plonked down so far but it's a start. Will do more as inspiration strikes.
 
Ahem, dont make me call in some lightning.

David did you get any more thought into this or the execution of how it may work?
 
I did the board design a couple of weeks ago. Here's the 3D render of it:

pc819.jpg


It has DMX input (and thru output), start address selection, 5V or 12V operation, separate trigger input, on-board fuse, etc. Might see if I can cram a few jumpers in for pixel type selection. Haven't thought about writing the firmware yet.

We just need someone like Alan (AAH) to do the pixel strobe board now!
poke-stick.gif
 
The 3D render above have been undated to reflect some changes (3 jumper positions added). I think that's all I can squeeze into that design. :eek:
 
Pretty :)
Before someone like AAH could do a pixel board design he'll need to know what's going to come out of the board.
I look at the board and with no idea how it's planned on working I could see it receiving dmx data and when the start address is reached it snaffles some bytes and pumps out some data in 2801,2811 etc format and uses the rgb pixels to produce strobing effects based on some snazzy firmware. I don't know how pixels compare with 1/2 white leds but if it worked like that it'd make it a breeze to setup strobe strings as all you need to do is plug in the strings straight from Ray. As the 2811 etc pixel data is fast you could do some fast effects on strings of 25 or 50 for instance that aren't dependant on the 25 Hz (roughly) refresh rate of dmx data. With 12V as the supply for the board I could see the board powering a string of 25 or 50 pixels. As the strobing isn't on a whole lot I imagine that the little reg would be able to do 50 5V pixels. That's just my thoughts. I'll catch you in chat at some stage soon David and we can discuss what magic smoke is going to be generated :)
 
Yep, you're pretty much on the money with the capabilities of the board. :)

I haven't provided an option to use the on-board 5V regulator to power the pixels. I was thinking that the pixel strobe boards would have high powered LEDs and a reasonable sized string would need more peak current than the OKI can safely supply. I've provided 5V and 12V power input options to suit 5V or 12V pixel strings/strobes. Same sort of deal as the power jumpers on my DC24 and DC48 DC controllers.

In theory, firmware should be able to be written to suit 6803, 2801 and 2811 pixel types. The 6803 and 2801 protocols are easy, but I don't have any experience in creating a 2811 data stream yet. I guess I'll find out what's possible once I get to that part.

This board could also run regular DMX-pixel firmware and be a big brother to my APC718 board too I guess.

I had an idea for using DIP switch 10 to put the board into a non-DMX mode. The first 9 DIP switches would then select the strobe flash rate and pattern, and the (isolated) trigger input would fire it. That way you could use a spare channel output of a DC controller to trigger this board.
 
I like the design and concept, wondering if it's cost effective? Any idea on a group buy what they could run?
 
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