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Thread: 5 volt matrix build problem, very confused... need advice

  1. #1
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    Default 5 volt matrix build problem, very confused... need advice

    I have built a full 16 string pixel tree 50 nodes tall and have had no problems getting it to work properly.

    So I took on the task of building a 2445 node matrix. It's all 5 volt pixels and it's a total of 1080 pixels. I have it split into 2 ports of 540 nodes each. Each 540 nodes section has 4 pwr injection points, 1 at top,1 at bottom and 2 in the middle,using 16awg landscape wire. Each 540 node section also runs on it own 300watt power supply. I am testing it off a pi cap. With the pi running off a wall wart and data only lines going into the matrix.
    When I hook it all up and plug in the pwr supply about 150 pixels randomly flash colors, the others do nothing. If I run the pi port with pwr,ground and data along with the 4 injection points. It still just flashes the 150 pixels and won't respond to the fpp sequence. I am very confused on this and dont know where to start. Do I need more pwr injection points?? Is 540 pixels to many for 1 port on the pi? I am total stumped here... any advice anyone could give me to try would be very helpful.

  2. #2
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    Default Re: 5 volt matrix build problem, very confused... need advice

    • Data alone is never enough. You must run data plus V- (aka ground) from the PI to the first pixel in the string.
    • If your power injection is as you say, then even if it did not support all white at full brightness, you should not have any flickering when most of the pixel are off or only set to a single color.
    • Even if you did not have enough power, the first few pixels should light up. Your issue is something else.


    Have you tested the PI hat with a known working string?

    Assuming the PI + Hat is working properly and is properly configured:

    Have you verified that the first pixel is connected properly?
    It is not unusual to have string come with the connectors on the wrong ends. Every vendor seems to do their own thing with the connectors.

    Does the new string work when connected to a different controller (that is known working)?

    The answers to these questions will drive the next steps in debugging.


    2020 Full sized show reworked for the new location. Only adding (famous last words) 13 RBLs that I finally got converted to using pixels
    2019 - Just moved into a new home (yet another change of plans). Will be dim but not dark. Too much to do at the new place to leave time for a show. Dim show (3000 pixels) had regular visits most nights.
    https://www.youtube.com/channel/UCyX...ttrsZNARkUce0Q

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    Default Re: 5 volt matrix build problem, very confused... need advice

    Quote Originally Posted by mister softee View Post
    Each 540 nodes section has 4 pwr injection points, 1 at top,1 at bottom and 2 in the middle,using 16awg landscape wire. Each 540 node section also runs on it own 300watt power supply.
    The ground from your Pi Cap needs to be connected to ground on every 540 node section. It doesn't have to be connected to the first pixel in each section. You can connect it to the power supply for each section or at any injection point. You might find it easier to simply connect the power supply grounds.
    Last edited by dcamron; 01-31-2019 at 10:18 AM.

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    Default Re: 5 volt matrix build problem, very confused... need advice

    The pi is working perfectly, I can hook other props to it. And reconfigure the pixel count and they work fine.
    I am not a newbie to the falcon controllers,ran an entire show this past year with another pi and multiple controllers.

    Now I do not have a ground on the first pixel string connected, just the data line. Every other string is connected together at the pwr supply. So let me try this first. Hopefully that is my problem.

    Strings are all from the same vendor, bought at the same time and are all connected the same direction.

  5. #5
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    Default Re: 5 volt matrix build problem, very confused... need advice

    Quote Originally Posted by dcamron View Post
    The ground from your Pi Cap needs to be connected to ground on every 540 node section. It doesn't have to be connected to the first pixel in each section. You can connect it to the power supply for each section or at any injection point. You might find it easier to simply connect the power supply grounds.
    Many people have found that relying on ground at the supply is not reliable. You should always run a ground along with the data line when moving from section to section or PI to First pixel.


    2020 Full sized show reworked for the new location. Only adding (famous last words) 13 RBLs that I finally got converted to using pixels
    2019 - Just moved into a new home (yet another change of plans). Will be dim but not dark. Too much to do at the new place to leave time for a show. Dim show (3000 pixels) had regular visits most nights.
    https://www.youtube.com/channel/UCyX...ttrsZNARkUce0Q

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    Default Re: 5 volt matrix build problem, very confused... need advice

    Quote Originally Posted by MartinMueller2003 View Post
    You should always run a ground along with the data line .
    That statement right there should be written in stone as one of the 10 Commandments

  8. Likes Ruppro, Little_b, Keith R liked this post
  9. #7
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    Default Re: 5 volt matrix build problem, very confused... need advice

    Also make sure the length of the wire between the pi and the first pixel is not too long

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    Default Re: 5 volt matrix build problem, very confused... need advice

    Well hopefully this is my problem, this is the first time I am trying to run a prop that only has data going to it with multiple pwr supplys. Usually 1 per supply can handle a good amount of pixels where if I just run 1 or 2 extra leads off of it I can pwr almost anything. But with this having alittle over 1,000 pixels in one. Area. I split it into 2 sections with multiple pwr supplys.

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    Default Re: 5 volt matrix build problem, very confused... need advice

    Quote Originally Posted by jackal24 View Post
    Also make sure the length of the wire between the pi and the first pixel is not too long
    I have had my (Rons) PI hat drive pixel data 4m without issue. Beyond that I always use a buffer so I do not know the actual limit.


    2020 Full sized show reworked for the new location. Only adding (famous last words) 13 RBLs that I finally got converted to using pixels
    2019 - Just moved into a new home (yet another change of plans). Will be dim but not dark. Too much to do at the new place to leave time for a show. Dim show (3000 pixels) had regular visits most nights.
    https://www.youtube.com/channel/UCyX...ttrsZNARkUce0Q

  12. #10
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    Default Re: 5 volt matrix build problem, very confused... need advice

    My normal layout is a PSU dedicated to the pixel controller. Data plus Ground to the first pixel, separate PSU for each 250W worth of pixels. Always run data plus V- across each PSU boundary. Never tie the V+ from multiple PSU boundaries together. I do NOT add a V- wire between the PSUs in the power box since there is no need to do that.

    The falicy in tying the V- together at the PSU is that the Data is "with respect to ground" AT the PIXEL. The "potential" on V- at the PSU is very different than the voltage potential at the pixel and makes a horrible reference point for data signals.


    2020 Full sized show reworked for the new location. Only adding (famous last words) 13 RBLs that I finally got converted to using pixels
    2019 - Just moved into a new home (yet another change of plans). Will be dim but not dark. Too much to do at the new place to leave time for a show. Dim show (3000 pixels) had regular visits most nights.
    https://www.youtube.com/channel/UCyX...ttrsZNARkUce0Q

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