Author Topic: P10 panel flickering outline  (Read 1135 times)

Offline rmp2917

  • Newbie
  • *
  • Join Date: Aug 2014
  • Location:
  • Posts: 27
  • Kudos: 1
P10 panel flickering outline
« on: July 13, 2017, 06:24:49 AM »
I just setup a 4x4 P10 panel using a PI3 and a matrix hat from CFOL. The panels are also from CFOL.

There is a random flickering outline or random background pixels flickering (See video). Has anyone seen this issue or know what might be causing it?

https://vimeo.com/225397993
https://vimeo.com/225398004

Offline jnealand

  • Developer
  • ******
  • Join Date: Aug 2013
  • Location: Kennesaw, GA
  • Posts: 2,078
  • Kudos: 38
Re: P10 panel flickering outline
« Reply #1 on: July 13, 2017, 10:24:39 AM »
First off be sure to close any open windows to the FPP.  It is a known problem that having an open interface window when running will cause flickering.
Jim Nealand
Kennesaw, GA
Lynx, Falcon, XL, FPP

Offline TNF250

  • Newbie
  • *
  • Join Date: Mar 2016
  • Location: SpringField, TN
  • Posts: 33
  • Kudos: 0
Re: P10 panel flickering outline
« Reply #2 on: July 13, 2017, 10:39:26 AM »
I'm glad you brought this up. I have the same issue even when scrolling the information, no windows open on FPP. Panels came from Ray Wu. I thought it was a power issue because I'm running it from a battery pack. 

Offline rmp2917

  • Newbie
  • *
  • Join Date: Aug 2014
  • Location:
  • Posts: 27
  • Kudos: 1
Re: P10 panel flickering outline
« Reply #3 on: July 26, 2017, 05:52:19 PM »
I've tried about everything I can think of and still have this flickering issue.

I'm pretty sure it is not a power issue. It happens even with only one panel connected and I'm using a 60 amp 5 volt mean well power supply. I also tried powering the Pi with a separate power supply, but get the exact same results. I've tried different cables and even a different matrix adapter.

It does it both in test mode from FPP and also while playing a sequence.

So, I don't know if it could be an issue with the panel itself or an issue with the Pi and FPP.

Any suggestions would be helpful.

Thanks, Rick

Offline Ebuechner

  • Full Member
  • ***
  • Join Date: Apr 2016
  • Location: Madison WI
  • Posts: 145
  • Kudos: 6
Re: P10 panel flickering outline
« Reply #4 on: July 27, 2017, 05:09:32 AM »
I've had a similar issue with panels I bought from Ray and Ron's pi adapter. What I found was it was the panels that were at the end of the data stream so I rearranged my panels so those panels are not in a prominent place on the display but in the corners.

Offline JonB256

  • Supporting Member
  • ******
  • Join Date: Mar 2013
  • Location: Granbury, Texas
  • Posts: 3,676
  • Kudos: 77
    • Granbury Christmas Lights
Re: P10 panel flickering outline
« Reply #5 on: July 27, 2017, 09:26:56 AM »
I see the flickering in the Videos. Since it is around the text, I'd suspect the Font being used rather than a panel problem.

The anti-aliasing used to make the font size changes may be causing it. Using Matrix tools, try drawing a few lines and see if you get anything around the lines.

If that text was moving, I don't think you would have that flickering concern.

I have a working 3x3 panel sitting next to me that I can use to duplicate your test if you describe it. (though I'm running an Octoscroller and dKulps newest BBB image)

Offline rmp2917

  • Newbie
  • *
  • Join Date: Aug 2014
  • Location:
  • Posts: 27
  • Kudos: 1
Re: P10 panel flickering outline
« Reply #6 on: July 28, 2017, 06:14:47 AM »
I used Matrix tools to create the test text in the video. I made the video with still text because you could see the issue easier.

I also tried drawing lines, changing fonts, scrolling the text, etc. The ghosting/flickering is till there regardless what is being displayed unless the entire panel is lit. Anything with a black background or unlit pixels shows the ghosting. I even tried running a sequence with different fonts. I have ran a sequence in bridge mode from xlights and directly from FPP with a scheduled playlist and no browser windows open. All tests show the same flickering regardless of the brightness setting or any other settings.

I don't think it would be a panel problem unless all 16 panels have the same defect or design flaw.

I found some documentation that shows similar ghosting and describes how to fix it by changing the PWM nanoseconds for LSB using the following: --led-pwm-lsb-nanoseconds : PWM Nanoseconds for LSB (Default: 130). But, I don't know where to change this in the FPP code. Here is the link: https://github.com/hzeller/rpi-rgb-led-matrix. There are some images and a description about half way down the page.

Right now the ghosting is bad enough that I'm not sure I will be able to use the matrix if I can't fix it.

Offline JonB256

  • Supporting Member
  • ******
  • Join Date: Mar 2013
  • Location: Granbury, Texas
  • Posts: 3,676
  • Kudos: 77
    • Granbury Christmas Lights
Re: P10 panel flickering outline
« Reply #7 on: July 28, 2017, 07:07:31 AM »
I tried duplicating your video and could not get that ghosting. My panels are about 3 years old so definitely a different batch and manufacturer.

Offline adster

  • Newbie
  • *
  • Join Date: Dec 2015
  • Location:
  • Posts: 30
  • Kudos: 1
Re: P10 panel flickering outline
« Reply #8 on: August 02, 2017, 09:31:41 AM »
Thank you for bringing this up! I, too, am having this same issue and I'm pulling my hair out. I don't think it's necessarily a panel issue because I've run test patterns on the panels and don't have the ghosting. Here's a video I made out of Xlights: https://youtu.be/mb5ZFugrdvI


The github link you referenced looks to be the exact problem (especially the "Ghosting with low --led-pwm-lsb-nanoseconds" photos). I wonder if we can summon CaptainMurdoch here to give his advice?

Offline dkulp

  • Sr. Member
  • ****
  • Join Date: Sep 2013
  • Location: Framingham, MA
  • Posts: 364
  • Kudos: 8
Re: P10 panel flickering outline
« Reply #9 on: August 02, 2017, 10:21:00 AM »
If any of you that are having this issue have a BBB and Octoscroller available, it might be worth while trying to duplicate it with the Octo to see if it's a panel issue or something with the timing of the PiHat code.
Dan Kulp

Offline jnealand

  • Developer
  • ******
  • Join Date: Aug 2013
  • Location: Kennesaw, GA
  • Posts: 2,078
  • Kudos: 38
Re: P10 panel flickering outline
« Reply #10 on: August 02, 2017, 02:00:47 PM »
I have seen this problem on my P5 panels, but since you have to be up close to see it, I have not worried about.  I doubt anyone will see it from most show viewing areas.  I'm not saying it is not a problem, but that it is not something that will affect my show so therefore a non-issue for me.

Offline adster

  • Newbie
  • *
  • Join Date: Dec 2015
  • Location:
  • Posts: 30
  • Kudos: 1
Re: P10 panel flickering outline
« Reply #11 on: August 02, 2017, 10:38:20 PM »
If any of you that are having this issue have a BBB and Octoscroller available, it might be worth while trying to duplicate it with the Octo to see if it's a panel issue or something with the timing of the PiHat code.

That is a good idea! I don't have an Octoscroller available (I have one on order from DIY LED EXPRESS since January but not sure when that's coming...) but I do have a BBB available. I also have a ColorLight control board available, but as far as I know the ColorLight board isn't working with FPP yet. I have reached out to CFOL to see if they have an Octoscroller available!

I have seen this problem on my P5 panels, but since you have to be up close to see it, I have not worried about.  I doubt anyone will see it from most show viewing areas.  I'm not saying it is not a problem, but that it is not something that will affect my show so therefore a non-issue for me.


I noticed it wasn't noticeable past a few fee either, but my sign will be next to the street so I just wanted to see if maybe there is a way to fix the issue instead of live with it. Especially now that I see other people are having the same issue.

Offline JonB256

  • Supporting Member
  • ******
  • Join Date: Mar 2013
  • Location: Granbury, Texas
  • Posts: 3,676
  • Kudos: 77
    • Granbury Christmas Lights
Re: P10 panel flickering outline
« Reply #12 on: August 03, 2017, 12:38:15 PM »
I don't see any flicker with the Octoscroller. I am running Dkulps latest version.

Sent from my SM-G900V using Tapatalk


Offline rmp2917

  • Newbie
  • *
  • Join Date: Aug 2014
  • Location:
  • Posts: 27
  • Kudos: 1
Re: P10 panel flickering outline
« Reply #13 on: August 13, 2017, 12:31:41 AM »
I was able to make some progress with this issue. Since FPP is using an older version of the RGB Matrix library, the settings shown in the documentation that I mentioned earlier are not available.

I was able to find a constant in the code that controls the PWM Nanoseconds for LSB. I manually changed it and rebuilt FPP using the following.

Code: [Select]
cd /opt/fpp/external/rpi-rgb-led-matrix/lib
sudo nano framebuffer.cc

modify the following line "static const long kBaseTimeNanos = 130;" and change 130 to 300
Save the file and exit

sudo make
cd /opt/fpp/src
sudo rm fppd
sudo make

I then restarted FPP and ran some tests.

The ghosting is now gone for the most part. It still seems to show a little when the text is first displayed but goes away completely after a second. So, I don't know if there is something else in the code that needs changed.

Would it be possible to update the library to the latest version and add this as a setting on the matrix page? I would be willing to do this myself even it was only on my local copy, but I am not that familiar with Linux or the FPP code. So, I would probably need a lot of help.
« Last Edit: August 13, 2017, 07:15:06 PM by rmp2917 »

Offline mtosh

  • Newbie
  • *
  • Join Date: Jan 2017
  • Location:
  • Posts: 13
  • Kudos: 0
Re: P10 panel flickering outline
« Reply #14 on: August 14, 2017, 05:48:10 AM »
I had same issue and ended up switching to bbb. That still wasn't enough and had to run the beta of fpp on the bbb. Has something to do with refresh rate on the newer panels.


Sent from my iPhone using Tapatalk

 

Back to top