LTDC CLK for 16bit RGB on a STM32L4+ having issues where there is a vertical line on the display.

[APesi.1]

The vertical Line seems to go away when I put a my finger on the LTDC CLK pin. I adjusted the clock frequency to above the minimum (12.5MHz) required for the display, and it still appears. I then added a 40k pulldown resistor to the LTDC CLK pin, and it went away, but I don't see any information anywhwere regarding the addition of the pulldown is an ok solution. I have read another post about the exact same issue, but the issue was closed out with no solution. Any help is greatly appreciated.

[Tesla DeLorean]

>> but I don't see any information anywhere regarding the addition of the pulldown is an ok solution.

Probably not really addressing the problem.

Seems to be more of a display side issue. What does the signal look like on a scope?

If it has a lot of ringing or overshoot, you might want to consider a series resistor, or look at dropping the slew-rate (SPEEDR) of the GPIO pin.

[Imen.D]

Hello @APesi.1​ ,

It seems the issue is with your code/configuration.

I would suggest adding more details about your configuration, so that Community users can help you.

Imen

[APesi.1 · Accepted solution]

Thanks for the Suggestions! We found a Fix!

Before the fix the LTDC CLK looked like:The line GPIO_InitStruct.Speed = GPIO_SPEED FREQ_MEDIUM (5 to 25MHz) was originally set to GPIO_InitStruct.Speed = GPIO_SPEED FREQ_LOW (0 to 5MHz).

After the code change:

Still has some ringing in the clock, but its working much better.

Thanks for the suggestions.

[Imen.D]

Thank you for your update.

Glad to know that the issue is solved 😊