Screen flickering sometimes

General discussion
1

I’m using v7.11 version for my application. Sometimes some flickering will show up, including horizental lines or just some chars show up and disappear, not sure whether I use the LVGL features correctly, or is it some problems caused by the LCD driver?
Attached the sample videos for the issues. Thanks!
LVGLv7.11_flickering.zip (481.0 KB)

2

Try a program with the lcd driver and no LVGL running. Then try that with LVGL without any widget, a single free window. if it persists in the first case, the problem is with LCD driver. If it happened in the second case, there is something with matching.

3 Likes
3

A blank LVGL screen won’t trigger the problem, but seems the more wideges I added into the screen, the more serious the flickering problem.

4

It seems like a hardware issue. Are there enough capacitors on the power supply of the display?

5

The hardware part should be ok. This is an eol update project, we replaced the legacy MCU with an IMXRT1062 without changing the LCD HW design, the old GUI based on PEG has no flickering problem. What else should I check or test to address it?
When power on, the screen is ok, then after a while, some random characters or lines will blink on the screen, but they should not apear in that area. And it seems related with the refresh task I assign to update the screen (i.e. label values), lower down the task frequency can help to improve it a little.

PS: I use FreeRTOS+LVGL for the GUI implementation.

6

If you you see the flickering after LVGL finished the rendering and nothing changes on the UI then it’s very unlikely that it’s an LVGL issue (as LVGL don’t draw anything)

I don’t know your HW setup but from IMXRT1062 I assume there is no display controller but you use the LCD interface of the MCU with a frame buffer in internal or external RAM. If you have just changed MCU then I’d check 2 things:

  • the clock frequency of the display on the LCD port
  • the configuration of the external memory (if you use it)
7

Thanks for the replies, I’ll debug it according to the suggestions and update the results after finish it.

8

Update:
Turn out the issue is caused by the memory setting, or by some issue in NOR XiP running. Anyway after transfer the same app to a different platform using HyperRAM, the issue disappeared.
Thanks for the help