I'm looking into interfacing with the TI 84+ CE's LCD over SPI with an ESP32-S3. I have a breakout board for the FPC, but don't know where to get started with controlling the display with SPI.

I've been looking at the datasheets linked on this page: https://wikiti.brandonw.net/index.php?title=84PCE:Ports:4000, but I'm not sure how I would send data to the registers of the PL111 controller.

How does the calculator do it? It seems like some variables are memory mapped to a region that is pushed to the screen over DMA?

Any help is appreciated.

It's a little bit confusing because the 84+CE actually has two LCD controllers. The PL111 sends timing and data signals to the SPI-based controller via the RGB interface. If you want info about the SPI-based controller, there's a datasheet linked here: https://wikiti.brandonw.net/index.php?title=84PCE:Ports:D000