TFT display flickering issue

[N Sornakumar]

Board name : stm32f746bgt6

Sdram : AS4C4M32SA-7TCN

My display size is 800*480, interfacing sdram & display with mcu successfully. But my display having flickering issue, Frame buffer stored in sdram..!

How to solve this error?

[Imen.D]

Hello @N Sornakumar​ 

I advise you to check this application note AN4861 describes the LCD-TFT display controller of the STM32 MCUs, and demonstrates how to use and configure the LTDC peripheral.

You can follow the provided example in the AN which is based on the STM32F746G-DISCO board and describing the steps required to create a basic graphic application. 

Hope my answer helped you!

When your question is answered, please close this topic by choosing Select as Best. This will help other users to find answers faster.

Imen

[N Sornakumar]

@Imen DAHMEN​ thankyou for your reply.

my display is working properly but issue is it's having flickering

[Imen.D]

Hi @N Sornakumar​ ,

I'm not sure about the reason of your issue.

Maybe trying to force the refresh will help.

I advise you to have a look at the LTDC examples under STM32CubeF7 package, it may be very helpful:

\STM32Cube_FW_F7_V1.16.1\Projects\STM32746G-Discovery\Examples\LTDC

Imen

[waclawek.jan]

> my display is working properly but issue is it's having flickering

As Imen wrote, you should read AN4861. Concentrate on Checking display compatibility considering the memory bandwidth requirements chapter.

JW

[QSHAO.1]

There may be way to see if the flickering issue is caused by memory bandwidth. to move frame buffer from external memory to internal memory or just reduce the data throughput between MCU and external memory by low resolution (for example 240x320 instead of 800x480) of display window on the LCD?

[N Sornakumar · Accepted solution]

It was clock issue. I am configured clock 9.8Mhz instead of 30Mhz

[FLuba.1]

I also had a similar problem. My screen was working properly, after adding a timer interrupt(each 1s the interrupt is generated), the display began to flicker. The solution was also, reducing the clock of the LTDC. Recommended clock according to the fabricant of the display is 8-12MHZ, i had to reduce to 7MHZ. I tried to change other timing parameters, but i didn't solve the issue, only reducing the clock of LTDC stopped the flickering. Can someone explain me why?

I use the RAM memory "AP Memory APS6408L-3OBM-BA", Nor flash memory  "Macronix MX25L12833F". My display is "DWIN LI48272T043HA3098". My actual clockfrequency is: RAM is 52MHZ, flash=104MHZ, display(LTDC) = 7MHZ,HCLK : 104MHZ. My mcu is STM32L4P5ZGTXP. In the past, the clockfrequency of LTDC was 8MHZ.