# Slideshow

This project is a relatively simple slideshow running on the Adafruit Feather
328P (an ATmega328p-microcontroller) using a simple button and a 240x240 LCD
display with the ST7789-driver over
[SPI](https://en.wikipedia.org/wiki/Serial_Peripheral_Interface).

This project is written on Rust and uses a very minimal amount of libraries with
the most significant being [`atmega-hal`](https://github.com/Rahix/avr-hal), a
hardware abstraction layer for ATmega-microcontrollers. Images are stored in the
[program memory](https://en.wikipedia.org/wiki/Flash_memory) of the device and
manually read using the `lpm`-instruction using inline-assembly because Rust
itself does not produce this instruction in any scenario. The images are stored
in the [QOI-specification](https://qoiformat.org/qoi-specification.pdf) to save
space, and they are decoded on-the-fly when rendering the images. Communication
between the display and the microprocessor is done manually using a [minimal
SPI-utility](https://rahix.github.io/avr-hal/atmega_hal/spi/type.Spi.html)
within the `atmega-hal` crate.

## Demonstration

<video controls src="./demonstration.mp4" alt="demonstration">