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Cheap Pixel decoder

Discussion in 'RGB Lights - Intelligent Pixels and 3-Channel RGB' started by chicken, Oct 4, 2015.

  1. chicken

    chicken Apprentice Elf

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    San Francisco Bay Area, CA
    looking for some ideas..... We run my parents large display off of 3 j1sys p12s'. They run great but we have a few wire frames that are rope light based that we want to add some pixels to. The wire frames rope lights themselves are powered via renard controllers but like to add some a dozen or two pixels to some of them, like our wire frame Christmas trees. The pixels would be for the star on top of the tree and to act as Christmas lights on the trees. We have about five wire frames we want to do this with and due to how spread out everything is and that the closest p12s is 50' away I was thinking of just chaining dmx off of the renard into one of Rays' dmx to spi decoders. I have used rays mini protocol decoder in the past but they are very limited. You have to order them in the right spi protocol, right voltage and the biggest problem for me is they are fixed on how many channels they strip out of the dmx stream. So if I have one decoder with 10 pixels and the decoders I order strip out 64 or 128 channels it limits how many I can chain together.


    Looking on rays site tonight I noticed these bc-820 decoders.
    http://www.aliexpress.com/store/product/BC-820-DMX-to-SPI-convertor-dmx512-signal-input-output-signal-selectable-supports-6803-8806-2811/701799_1788825711.html


    They look like they solve all of my issues. Spi protocol selectable, auto voltage detection, easy to set start channel and what looks like the ability to adjust how many channels it strips out of the dmx stream before you daisy chain another dmx device off of it. I emailed Ray to confirm that's how these work. I assume that as they allow you to set how many pixel channels they need to support. I assume from there they just pass the dmx stream from there.


    A lot to digest there but I wanted to see if anyone else has used the bc-820s before and if the channel numbering works as I explained here. Also if you have used these before how well have they worked for you. The only downside seems to be cost. The mini decoders I used from Ray in the last are $16 vs these at $29 each. Any other ideas on relatively cheap but reliable solutions to what I need? I would like a single port e1.31 to spi adapter but I don't see anything in this price range.


    Thanks!
     
  2. i13

    i13 Senior Elf

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    Are you sure that these are stripping channels out of the DMX stream?

    I know that for DC controllers such as the AAHmega60, the DMX in and out ports are wired in parallel and can be used interchangeably. The DC controllers simply read the signal as it passes by them. All DC DMX controllers receive the same DMX signal and you can even have multiple ones with the same start channel doing the same thing. Are you sure this isn't the case with Ray's decoders/convertors? It would be easy to test either by assigning the same channels to two of them or by connecting your DMX input to the decoder's DMX output (the former option is the safest IMO).

    If this is the case then you don't have to worry if they aren't using all of the channels they can support. You can still make use of the unused channels by assigning them to another DMX device. Remember termination will be a good idea if this works.
     

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