Do we need additional SDRAM/SRAM Interface for TFT Display.

[Adrush Rawal]

Hi,

we are planning to change current LCD with 10 inch (800*600) TFT Display with TouchGFX and already we are using QSPI flash, do we need additional memory interface (SDRAM/SRAM)?

Regards,

Adrush

[Peter BENSCH]

This depends on your current circumstances, e.g. the STM32 used and its size of internal RAM, the buffer strategy and the colour depth.

Your SVGA display with 800x600 pixels has a total number of 480000 pixels. At full colour resolution (RGB888) the frame buffer requirement is 480'000 * 24 = 11'520'000 bit (=1.373MB). If you also need double buffering, this value doubles again and you definitely need external RAM.

However, you can usually work with a lower colour resolution of RGB565 (65536 colours) instead of RGB888 (16 million colours), because the difference is rarely noticeable on displays with smaller dimensions. Instead of 24 bits per pixel, RGB565 only needs 16 bits, which reduces the RAM requirement by 33.3%. In your case, "only" 960'000 bits (937.5KB) are needed for a frame buffer, and 1.875MB for double buffering.

Regards

/Peter