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Thread: 5v WS2811 pixels flickering after power injection

  1. #1
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    Default 5v WS2811 pixels flickering after power injection

    Hey all, having a strange issue, wanted to see if my reasoning on this is correct. Some details:
    • There are 11 total boscoyo stars with 90 pixels each, 6 on one port, 5 on a second port
    • The ports are driven by one differential receiver each connected to a Falcon F4v3 (overkill for this display, but practicing for the ~6k pixels at christmas)
    • Each star is its own unit and has a connector for data in only, data out only, and for dc +/-
    • I'm using a power distro board alongside each differential receiver, targeting no more than 300 pixels per lead
    • The connection is basically data from the receiver to first star, then to second star, etc. on to the sixth star, while one power cable goes to stars 1, 2, 3 and a second cable goes to stars 4, 5, 6

    The problem I'm encountering is this: when I run a test pattern from the receiver, from the controller, or from the pi player the first three stars are stable, but the second three stars have a flicker issue which kinda looks like a twinkle effect (random pixels in each of the last three stars blink random colors). The only connection between star 3 and 4 is the data line; the power for the two sets of stars come from different ports on the distro board. The power is good at the start of stars 4-6, so I don't feel like that's the problem. I figured I'd try to connect the ground between the two and that seemed to work on one of the sets of stars I'm dealing with, but not with the other one.

    Any other ideas on what could be causing this?

  2. #2
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    Default Re: 5v WS2811 pixels flickering after power injection

    Some additional troubleshooting I've done
    • connecting the ground between 3 and 4: this worked but only when doing the test pattern on the differential receiver. Controlling the lights from the controller still had flickering
    • Upgraded the cable from the power distro board to star 4 (approx 25 feet) with 12ga (was 14ga) just in case it is a power issue. No discernible improvement, and I don't have the same problem with the other bank of stars despite having the same length of cables
    • Running a sequence rather than the test pattern. No discernible improvement


    One thing I did which was weird (well, even weirder) was removed star 1 and replaced it with a cable so I could just look at stars 2-6 (needed to fix something on the stand for 1). When I reconnected 1, everything worked, no flicker. Then I removed the additional data cable and it went back to flickering. This is all very confusing since that star is not next to the affected stars.

    Right now, I'm at wit's end. Because it works fine from the differential receiver but not from the controller (the two are connected by 100' Cat6 which is well within the 250' allowable) it feels like a signal issue, but it's very weird that it would affect only half the pixels on a given port rather than the entire port. Any help or ideas are welcome; thanks in advance.

  3. #3
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    Default Re: 5v WS2811 pixels flickering after power injection

    and, since pictures are worth a thousand words, here's a diagram of my layout. The power wires for the stars are connected at both ends for simplified power injection
    Capture.jpg

  4. #4
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    Default Re: 5v WS2811 pixels flickering after power injection

    Though you do have a common ground at the distro, I would still connect the grounds between star 3 and star 4. The distance could be causing signal line differences.
    I would also make sure there is a ground between the Diff Receiver and Star 1. The ground/return for the data is real important.

    Our rule is to always connect a like return for every data connection.
    Live, Laugh, Love.

  5. #5
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    Default Re: 5v WS2811 pixels flickering after power injection

    algerdes beat me to it...ground and data flows together
    Last edited by roggerrabbitt; 06-21-2021 at 09:20 PM.

  6. #6
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    Default Re: 5v WS2811 pixels flickering after power injection

    Al is just too fast, send data and Ground from the controller (or diff receivers)
    Matt

  7. #7
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    Default Re: 5v WS2811 pixels flickering after power injection

    I added the ground between stars 3 and 4 and didn't see any improvement; stars 4, 5, 6 still flicker, but stars 1, 2, 3 are stable. Seems weird that adding a ground to the first set of pixels which are stable should help the ones further down the line, but I'll give it a shot. Thanks!

  8. #8
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    Default Re: 5v WS2811 pixels flickering after power injection

    Did you try to remove stars 1 - 3 to see if you still have an issue. I would also try re-ordering the stars to see if the problem moves, as it might be a bad connector.

    Thanks,
    Shawn

  9. #9
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    Default Re: 5v WS2811 pixels flickering after power injection

    I think it is best if you think of it as a 4 wire system. POWER (voltage) V+ and V- (not ground, but we use that tag a lot) and DATA D+ and D-
    There must be a V- for every V+ and also a D- for every D+, however, most of the time we run V- and D- on the same wire, turning a 4Wire system to use only 3Wires.

    Your sketch clearly shows you run V+ and V- correctly, but I only see D+ Provide D- to every star.
    In Lights Therapy

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