DMX - Pixel board with stepdown regulator

Discussion in 'The Development Lab' started by David_AVD, Apr 23, 2011.

  1. David_AVD

    David_AVD Good news, everyone!

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    I have been thinking of designing a new board with DMX input and one SPI (pixel) output. It would also have an on-board DC-DC converter. This would allow you to push 24V + DMX around the yard, daisy chain style (looping in and out of each element). The pixel string / strip would be 5V / 12V and the on-board regulator would convert from the incoming 24V and greatly reduce the voltage losses in the cable.

    I know some say "DMX - SPI is a dead duck", but I don't agree. It comes down to topology. Ethernet would require the data cables to be "home run", whereas DMX can be daisy chained. I am thinking that this board would be useful for things like mini trees where you only have 50 pixels max.

    Now, as to the question of an isolated DMX input, I think for a daisy chain situation, the extra parts cost would be hard to justify. Maybe the board can be offered in isolated and non-isolated versions.

    So, what's the interest factor here?
     
  2. dmoore

    dmoore Senior Elf

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    I'm in - this sounds a bit like a version 2.0 of the TP3244. I think, like you, that there is a need for a distributed DMX to SPI board.
     
  3. OP
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    David_AVD

    David_AVD Good news, everyone!

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    So, I was thinking of:

    • 24Vdc power input with polyswitch protection
    • Selectable 5Vdc / 12Vdc pixel power
    • Non-isolated DMX input
    • 5 pin pluggable "Phoenix" connector for power + DMX
    • 4 pin pluggable "Phoenix" connector for pixel string
    • Optional RJ45 for power + DMX
    • ICSP header for firmware upgrades

    The power + DMX via RJ45 option could be used where you have display elements spread out and daisy chaining the power + DMX isn't suitable. A central power + DMX splitter could be made too.
     
  4. fasteddy

    fasteddy I have C.L.A.P Global Moderator Generous Elf

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    Definetly not a dead duck, It comes down to choices, some want DMX others want E1.31 and I want both
     
  5. dmoore

    dmoore Senior Elf

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    I like the power over CAT5+DMX option! Like a DMX SS controller.
     
  6. kool-lites

    kool-lites Full Time Elf

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    David_AVD

    David_AVD Good news, everyone!

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    So, given the proposed specs / features, tell me what types of elements you might use this new board for. That way I can possibly tune the specs to make it better / more useful for all.
     
  8. tpboyce

    tpboyce New Elf

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    Hopefully it support HyperDMX? I might be interested for some mini trees.
     
  9. neilric99

    neilric99 Full Time Elf

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    good job David,

    I could use 4 of this type of board for my light poles with stars.

     
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    David_AVD

    David_AVD Good news, everyone!

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    Getting the right balance of cost, size and current output for the step down regulator section is tricky. For example, a 50 x WS2801 string draws approx 3 Amps @ 5V. One common type of regulator is rated for 3A, but I'd like a bit of headroom. The board's own circuitry needs power too, so using 50 x WS2801 pixels with a 3A regulator is really not a good idea. Higher current regulators are available, but for more $$ of course.

    So, how many pixels would people envisage using with a board like this? Keep in mind this board is meant for smaller "pockets" of pixels (mini trees, etc), not large runs.
     
  11. chilloutdocdoc

    chilloutdocdoc Full Time Elf

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    I see 50 being a good number, and personally what I would use it for.

    We have yet to see some $$ numbers. Even if they're ball-park (within $10 one way or the other) maybe it would help some gauge interest?
     
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    David_AVD

    David_AVD Good news, everyone!

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    I've re-started this project today. Got about 40% of the design done now. :)
     
  13. mrpackethead

    mrpackethead Full Time Elf

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  14. OP
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    David_AVD

    David_AVD Good news, everyone!

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    I can see what you mean, but it's not quite the same comparison IMO as the scales of data and cost are different.
     

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