Crate carousel 

Time-driven page cycler for small displays.

A Carousel answers one question: given the current millisecond clock and whether an external trigger fired, should the display show its idle screen or one of the cycle pages, and which page?

It is pure scheduling. There is no rendering, no I/O, no atomics, and no timer ownership here. The caller owns the framebuffer, the clock source, the trigger, and the CarouselState; this crate only maps (now, triggered) to a Frame. That keeps the timing logic no_std, allocation-free, and unit-testable without hardware.

use carousel::{Carousel, CarouselState, Frame};

const SCREENS: Carousel = Carousel {
    page_count: 4,
    page_duration_ms: 5_000,
    cycle_window_ms: 60_000,
    cycle_period_ms: 5 * 60_000,
};

// Offset the first auto-cycle so the idle screen shows right after boot.
let mut state = CarouselState::new(SCREENS.cycle_period_ms);

// Each render tick, feed the clock and any pending trigger:
match SCREENS.frame_at(&mut state, now_ms(), button_pressed()) {
    Frame::Idle => { /* draw the idle screen */ }
    Frame::Page(index) => { /* draw page `index` */ }
}

Structs

Carousel

Declarative cycle configuration.

CarouselState

Mutable carousel state, owned by the caller’s render loop.

Enums

Frame

What the caller should draw this tick.