Image widget drawing issue while Box widgets are ok

[KT]

I'm working on a project based on STM32F769ii MCU with external Flash via Qaud-SPI and 480x800 DSI LCD(no onboard GRAM). I have successfully integrated TouchGFX into my project however I see unexpected artefacts with the image widgets. Box widgets are drawn correctly. I use a button in my project to invalidate the image and box widgets to force them to be redrawn by doing so image widgets colour is wrong 80% of the times with no issues with the box widget.

TouchGFX is set up for double buffering with each buffer located in a separate bank on the SDRAM chip. moving the image files into the internal flash didn't solve the issue. I also tried RGB888 and RGB556 configurations, the system behaves the same.

The first image is what I'm expecting to see and the second image is what is depicted on the LCD.

Any idea how I can fix this issue?

[Romain DIELEMAN]

Hi,

Have you tried with other images to see if it was all images that are not properly handled or if it is just this one ?

/Romain

[KT]

Yes I tried with other images the same issue, and sometimes half of the image is missing while background box colour in that area is fine.

It looks like DMA2D and the LTDC both try to access the same buffer at the same time. I could provide you with the cube MX project file which is used to configure TouchGFX, LTDC, DMA2D and DSI peripherals, if needed.

Regards,

KTaw

[Romain DIELEMAN]

I can have a look, I can't promise anything thought 😅

/Romain

[KT]

Thanks Romain. That would be much appreciated.

Meanwhile I was wondering if you have any working TOUCHGFX project for STM32F769I-DISCO in video mode. this could me to investigate the issue.

Cheers,

KTaw

[KT]

Hi Romain,

Enclosed is the adapted STM32F769i-DISCO project from DSI Adaptive Command Mode to DSI Video Burst mode, along with two images first one screenshot of the TouchGFX designer and the other one the LCD output image. As you see the LCD image is corrupted.

To confirm that the LTDC and DSIHOST setting are correct, the software depicts two images image_320x240_argb8888 and life_augmented_argb8888 in two seconds intervals if USER_IMAGE_TEST macro-definition is activated without any issue.

TouchGFX screen output on the LCD when the project is in original adapted video mode is correct.

Could you please have a look at the project and advise me how could it be fixed.

Cheers

[KT · Accepted solution]

The issue has been rectified by enabling QUAD-SPI's "Sample Shifting" feature.

[Romain DIELEMAN]

Great to hear that 👍 How did you know you had to change that in the end ?

/Romain

[KT]

The clue was in the behaviour difference between image and box widgets. Box widgets don't use QSPI resources whereas Images are fetched from QSPI if they are located at the external flash. My initial QSPI test, at the beginning of the project, was based on the button widget which has a smaller size image, so the issue wasn't occurring there. But with a larger size image because the QSPI is fetched more frequently the issue surfaces itself.

Regards,

KTaw