Waveshare 4.3B – Heavy ghosting / flickering on firmware V2.0.2.2

[Evo609]

Hello,

I’m experiencing a serious display issue on the Waveshare 4.3B screen when using firmware V2.0.2.2.
The screen shows very strong ghosting / smearing and visible flickering, making it hard to read or use normally.

Details:

Device: Waveshare 4.3B

Firmware: V2.0.2.2

Problem: heavy smearing / ghosting, looks like constant flicker or refresh artifacts

I have tested older firmware versions and the issue does not occur there, so it seems to be introduced specifically in V2.0.2.2.

Steps to reproduce:

Flash firmware V2.0.2.2

Use the screen normally (menus / text / UI)

Observe strong ghosting and flickering

Expected behavior:
Stable image without smearing or flickering (like in previous firmware versions).

Actual behavior:
Visible smearing/ghosting and flicker on most screen updates.

Please let me know if you need logs, video, or additional information.

[Builty]

Hi. That's upsetting ;(
I did change the 4.3B LCD pixel clock in this version.
Could you please post a brief video. I'm just wanting to see it so it helps me when I try to reproduce (my plan would be to lower the pixel clock further as a test and see if mine starts to be behave like yours.)

[Evo609]

Hi. That's upsetting ;(
I did change the 4.3B LCD pixel clock in this version.
Could you please post a brief video. I'm just wanting to see it so it helps me when I try to reproduce (my plan would be to lower the pixel clock further as a test and see if mine starts to be behave like yours.)

Sure, it's hard to get that on the camera. 25fps and shutter speed set to 180 degree using Blackmagic iPhone app to match screen flickering. https://github.com/user-attachments/assets/5d0bac4e-b28b-4709-97bc-52012615b5d6

[Builty]

Thanks, yeah that looks like trhe pixel clock being too low. Likely some tolerances involved.
I will review the spec sheet and look at increasing it.

[Builty]

Hi. Could you please try this alpha version.
There are very few changes from V2.0.2.2. I have increased the LCD pixel clock and optimised the graphic buffers.
I think it will fix the issue for you.
Thanks.

TonexController_V2.0.3.2_test_Waveshare_4_3B.zip

[Evo609]

Hi. Could you please try this alpha version.
There are very few changes from V2.0.2.2. I have increased the LCD pixel clock and optimised the graphic buffers.
I think it will fix the issue for you.
Thanks.

TonexController_V2.0.3.2_test_Waveshare_4_3B.zip

Unfortunately this didn't fix the issue :( Flickering is still visible and there is a new problem https://github.com/user-attachments/assets/0416cf7f-6225-47ca-bda4-174e543b36f0

[Builty]

Thanks for testing. The small sideways jitters occur when the CPU is not able to transfer data to the LCD fast enough. A lower pixel clock gives more time for this, but also risks flicker if too low. The point of flicker is subject to display tolerances.

The test build worked OK on my board. I will test more thoroughly on some other 4.3B boards and see what has gone wrong.

[Builty]

Hi. Please try this one.
The pixel clock is 1 MHz higher and other parts of the system optimised to minimise DMA stalls.
I still get the occasional brief glitch when changing presets with amp skins configured, but its very minor.
I may be able to improve on that but I need to know if this pixel clock value is good first.
Thanks.

TonexController_V2.0.3.2_test_2_Waveshare_4_3B.zip

[Builty]

I was testing an unrelated change, and the DMA stalls came back. I'm not sure why yet.
Please do test the above version still, but the chance that it fixes everything is pretty low.
Hopefully we can at least verify the pixel clock.

[Evo609]

I was testing an unrelated change, and the DMA stalls came back. I'm not sure why yet. Please do test the above version still, but the chance that it fixes everything is pretty low. Hopefully we can at least verify the pixel clock.

Well, I think the flickering is a litte bit better now but still visible, thank you for trying!

[Builty]

OK I got the pixel clock up another MHz, and did a new double buffer/bounce buffer/porch timing tweak which seems to have done the trick:

TonexController_V2.0.3.2_test_4_Waveshare_4_3B.zip

[Ro1and1990]

Хорошо, я увеличил тактовую частоту пикселей еще на МГц и внес новые корректировки в настройки синхронизации с использованием двойного буфера/буфера отскока/сигнала прерывания, что, похоже, решило проблему:

TonexController_V2.0.3.2_test_4_Waveshare_4_3B.zip

Спасибо! Была такая же проблема, данная прошивка всё решила!