Rust async driver for SSD1331-based displays

Uses embedded-hal(-async) to communicate with the display. Provides methods to initialize the display and to send pixel data from the MCU to the display-side framebuffer.

To generate the pixels on the MCU side, one can use embedded-graphics crate with a framebuffer in the MCU RAM. That framebuffer doesn't need to be as large as the entire display (which takes 12KB in 16-bit color mode).

Example code

Under examples/, there's a demonstration firmware for STM32F103 you can run e.g. on a Maple clone with cargo run --release --example main.

Can we directly draw to the display-side framebuffer?

I tried writing a direct-to-display implementation of DrawTarget trait. With that approach, drawing is necessarily synchronous, pretty slow (as sending a single pixel requires an 8-byte transfer), and sometimes needs delays to allow the display controller to rewrite its RAM. Overall, it's workable but slow enough to get visible flickering when redrawing the entire screen. At least for now, I'm going to stick with the MCU-side framebuffer.