I have been playing with a very nice 320x240 display on an Arduino shield. It uses a ILI9320 controller and its 8-bit interface. Other displays use 16-bit i/f have a 20x2 pin header that requires an adapter shield for a Mega.
Since any display for an Arduino tends to have its pins split over PORTs, any write functions become a little complex.
So I was wondering about using the SPI i/f of the ILI932x controllers. A 16-bit SPI transfer will take 32 cycles. Whereas a 16-bit PORTx, PORTy transfer could be 4 cycles, a UNO 8-bit split version will be 24 cycles. Some libraries are VERY inefficient, and take 100s cycles per 16-bit.
Most TFT displays on Ebay are designed for parallel 8-bit or 16-bit. Has anyone found one that uses the SPI i/f ? Or even a 16-bit one that can change the mode bits for SPI ?
Most importantly, has anyone experience of using SPI mode on the larger displays? If it works ok, they would make very attractive Arduino shields. And still leave plenty of spare GPIO.
I have ordered a ST7735 160x128 module, but I would prefer a 320x240 display.