LTDC pixel format 565 does not produce output without CLUT being enabled

[yusuf1809]

I am using STM32f756 Nucleo board. I have an rgb lcd interfaced via 18 bit (rgb666) connection with the mcu. I have previously used pixel format L8 with CLUT and successfully produced output on the display. Now, I have changed the pixel format to rgb565, changed the frame buffer to 16 bit and populated it with rgb565 values for each pixels. But there is no output on the display unless I enable the CLUT again. I understand that CLUT is only useful for 8bpp. I don't understand why in RGB565 pixel format, the display doesn't show anything without enabling CLUT.

My setup is as follows -

The frame buffer is a 16 bit 240x320 array. The moment I comment out the 5 lines from the bottom, disabling the CLUT and the frame buffer is updated with rgb565 values, there is no output. When these lines are un-commented and the frame buffer is populated with 8 bit values, I can see the output on the display.

Any idea what might be causing this issue?

[KDJEM.1]

Hello @yusuf1809;

I think same issue is reported here.

Could you please confirm that the issue is solved when the layer 0 alpha is set to 255?

Thank you for your contribution.

Kaouthar

[yusuf1809 · Accepted solution]

Hello @KDJEM.1 

Yes, this is the same issue. This one was created because I couldn't move the other topic from the TouchGFX area.

Yes, the issue is solved when layer 0 alpha was set to 255.

Thank you