Waveshare 4.3b Screen flickering and sizing issue with latest 2.0.3.2

[erich74]

Hi Greg,

I've been running the beta version of the 2.0.3.2 for a while and now I have just flashed (full erase) the stable version.
With this version I have an issue with the display on my waveshare 4.3b.
This is the first time I have it, never had any such issue with previous fw.
Note that my 4.3b is supplied 9V by my pedalboard power supply and then connected by usb to the Tonex One but I have the same issue when I supply to unit with my computer through USB.
It does not happen all the time, sometimes I recycle the power on the 4.3b and then it works fine.

Here is the short video of what happens:

https://transfert.free.fr/3JpnDHk

Thanks for your support
Eric

[Builty]

Damn it. These kind of issues have caused me a huge amount of troubles. They only occur on the 4.3/7" models as they use RGB mode which means the processor has to refresh the LCD itself instead of using a frame buffer on the LCD.

The glitches occur when the DMA transfer from processor to LCD doesn't occur fast enough. If I lower the pixel clock it often fixes that but then some users ended up with constant flicker.
I've done a lot of optimising and experimenting (weeks of it.)

Sorry but there won't be quick easy fix here, but I will again do more testing and debugging.
Thanks for letting me know,

[erich74]

I totally understand how frustrating it can be. Don't worry I can live with it.
I did not have any such issue with the beta version, only with the latest stable.
Do not hesitate to tell me if you want me to test something when you do more debugging

Thanks again for all what you've been doing with this project

[Sombrero-Joe]

Is there any difference in the code between version 2.0.3.2 Beta 2 and version 2.0.3.2 Final?

[Builty]

@Sombrero-Joe No difference between beta 2 and final for the 4.3B. The only change that occured was fixes for the Pirate Midi Polar Max v2.

@erich74 which beta were you running that didn't have this issue?

[erich74]

To be honest I do not remember. I’ve been running it for a while so it was probably the first beta version

[Sombrero-Joe]

I also experienced various, very similar display glitches with my 4.3B. Sometimes these occurred after installing a new firmware update. But they also happened when I reinstalled a previous update, even if it hadn't shown any of these glitches before. After connecting all the ground contacts directly at the display of my 4.3B in a star configuration with a 2 mm² ground wire, I no longer observed these display glitches.

[Builty]

I hadn't thought about mentioning this, but this is interesting. The grounding could affect the signal integrity.

[erich74]

I see there are 3 gnd pins on the green terminal block. Do you mean grounding them together ?

[Sombrero-Joe]

Yes! And with the thickest possible ground wire that just fits into the screw terminals.

[erich74]

Thanks a lot, I’ll try this week and let you know !

[erich74]

I grounded the 3 GND connectors together but still the same, sometimes it's fine sometimes it has those glitches :(
I also tried powering the waveshare with usb pd instead of my pedalboard power supply but this is the same.

[Sombrero-Joe]

Perhaps completely deleting the firmware and then reinstalling it, now that there's a good ground connection, will help. 🤷‍♂️

[erich74]

Yes thanks that's what I will try next

[erich74]

I have flashed 3 times but still the same...Sometimes it works sometimes not.
It was working with previous fw but I like the improvements on the latest fw so I will leave it as it is

[Builty]

I realised that my own pedal board 4.3B was running a beta release. I updated it and now I also have the flickering.
At least I can reproduce it now. I will test again on my other 4.3B and try to see what I have missed here.