Touchgfx TFT Display Flickering Issue

Chandan Bhatia1 · ‎2020-10-08

Hello, I am using display TCXD050ABLON (Data sheet Attached) with STM32F746. As per datasheet I did below LTDC setting and still display is flickering badly.

Few screen shots of display setting as per datasheet is below.

Few Images of flickering display is as below.

Any suggestions?

MM..1 · ‎2020-10-15

When i see your images from first post, this dont seems as ltdc trouble. Try check firstly display and ltdc without touchgfx started.

I mean your troble is SDRAM when you use external.

For test only display prepare in flash memory fullscreen image in proper format and replace address in ltdc layer config to this image.

Then in main disable starting touchgfx resp all rtos.

View solution in original post

Imen.D · ‎2020-10-08

Hello @Chandan Bhatia ,

Ensure that you have enough RAM and try improve the performance.

You can have a look on how achieving Better Performance with CacheableContainer, I hope this helps you !

Imen

When your question is answered, please close this topic by clicking "Accept as Solution".
Thanks
Imen

Chandan Bhatia1 · ‎2020-10-08

@Imen DAHMEN Its static images so don't think this problem can occur. Anyway I am using external RAM for it.

Btw did you check my LTDC setting ? Does it look correct as per requited TFT settings?

Can you please check? I put few screenshots of datasheet down in post.

Alexandre RENOUX · ‎2020-10-08

Hello,

Have you used CubeMX for your LTDC settings ?

Because this should be automatically generated by CubeMX if you put the values in the lTDC settings in CubeMX.

For instance AccumulatedActiveH should be calculated as follows :

AccumulatedActiveH = Vertical Synchronization Width + Vertical Back Porch + Active Height - 1 = 4 + 8 + 480 -1 = 491

Also where is your image stored ? In your external Flash ? If so, are you sure your external Flash is correctly set ?

To check you could store the images in internal Flash or use shapes and boxes to see if you have some artifacts on the screen.

/Alexandre

Chandan Bhatia1 · ‎2020-10-08

@Alexandre RENOUX

I am using internal flash for initial testing. Also have used CubeMX for initial settings. As display was flicking I was changing paraments like AccumulatedActiveH directly from code.

I feel like issue is with horizontal synchronization, vertical synchronization, data enable, pixel clock polarity. Is it fine as per you ?

Chandan Bhatia1 · ‎2020-10-08

I tried below combine too.

Alexandre RENOUX · ‎2020-10-08

I guess you tried the config LTDC_HSPOLARITY_AL, LTDC_VSPOLARITY_AL, LTDC_DEPOLARITY_AL and LTDC_PCPOLARITY_IPC.

Please try try to remove you image and put a box instead, does it display correctly ?

Could you show me your clock config ?

/Alexandre

Chandan Bhatia1 · ‎2020-10-08

@Alexandre RENOUX My clock settings are as below ?

Also Does correct config is LTDC_HSPOLARITY_AL, LTDC_VSPOLARITY_AL, LTDC_DEPOLARITY_AL and LTDC_PCPOLARITY_IPC ?

Alexandre RENOUX · ‎2020-10-09

Yes I do think that the config I mentioned is the correct one.

Maybe could you try changing the LTDC clock to something lower (9.6 MHz for example like the F746G-DISCO) and see how it behaves ?

/Alexandre

Chandan Bhatia1 · ‎2020-10-09

@Alexandre RENOUX

One doubt, Horizontal sync signal. Default negative polarity, When not used, user should connect it to “Low�?. means it should be LTDC_HSPOLARITY_AH. I think.

Also same doubt for others polarity. Can you please clear it.