LTDC CLK for 16bit RGB on a STM32L4+ having issues where there is a vertical line on the display.
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‎2021-03-16 9:19 AM
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.
Solved! Go to Solution.
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LCD-LTDC
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STM32L4 Series
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‎2021-03-16 12:08 PM
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.
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‎2021-03-16 11:14 AM
>> 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.
Up vote any posts that you find helpful, it shows what's working..
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‎2021-03-16 11:20 AM
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
Thanks
Imen
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‎2021-03-16 12:08 PM
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.
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‎2021-03-17 5:56 AM
Thank you for your update.
Glad to know that the issue is solved :smiling_face_with_smiling_eyes:
Thanks
Imen
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