LCD 24bpp color mode vs 16bpp color mode and no of layers

[ATank.1]

Am using STM32H745BIT6 controller with LCD 800x480 and 16MB SDRAM with 16bit data bus for LCD framebuffer.

Am in a dilema whether to use 24bpp or 16bpp and have a few questions,

I have already gone through the Application note AN4861 and I have to say the data given is very informative.

As my SDRAM data bus is 16bit so in one cycle 16 bit data can be transfered that means if I use 24 bpp 2 cycles will be needed. So this will be slower than using 16 bbp where 16bits are transfered at once. Please confirm this. Or another way would be to go for 32bit SDRAM data bus which I think is not needed

1. For my configuration above 800x480 and 16 bit SDRAM with 16bpp would be sufficient as per my calculation. Please confirm.
2. Is there any advantage of using 24bpp (888 color mode) vs 16bpp (565 color mode). In above case the performance would be affected by using 24bpp.
3. Is there any advantage of using 2 layers instead of 1 layer?
4. Can 2 layers be used with 2 LCD frame buffers?

Thanks

Anuj

[MM..1]

You dont define LCD type, but asume LTDC .

As AN say you need match display rate with memory and bus capacity.

I mean your config is ok.

Q:

1. ok
2. advantage is in image quality if you show for example foto
3. yes based on usage good is one layer from ram second from flash, worse is both from ram
4. dont understand q?

[ATank.1]

Thanks for the reply. Using TFT LCD with RGB parallel. So Yes LTDC.

1. fine
2. Visually not much difference observed with 24bpp compared with 16bpp. Performance will be better with 16bpp as less data to transfer.
3. ok
4. I meant to say no of Layers are independent of no of frame buffers. are there any disadvantages of using 2 layers and 2 LCD framebuffers.

Thanks

Anuj

[MM..1]

4 more as one buffer have advantage in animation, disadv in memory usage