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Add readme for embassy-time

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Ulf Lilleengen
2022-08-23 13:57:45 +02:00
parent 7b3ae0446c
commit 189d4137cc
2 changed files with 44 additions and 42 deletions
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embassy-time/src/lib.rs
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@ -1,50 +1,9 @@
#![cfg_attr(not(any(feature = "std", feature = "wasm")), no_std)]
#![cfg_attr(feature = "nightly", feature(generic_associated_types, type_alias_impl_trait))]
#![doc = include_str!("../README.md")]
#![allow(clippy::new_without_default)]
#![warn(missing_docs)]
//! Timekeeping, delays and timeouts.
//!
//! Timekeeping is done with elapsed time since system boot. Time is represented in
//! ticks, where the tick rate is defined by the current driver, usually to match
//! the tick rate of the hardware.
//!
//! Tick counts are 64 bits. At the highest supported tick rate of 1Mhz this supports
//! representing time spans of up to ~584558 years, which is big enough for all practical
//! purposes and allows not having to worry about overflows.
//!
//! [`Instant`] represents a given instant of time (relative to system boot), and [`Duration`]
//! represents the duration of a span of time. They implement the math operations you'd expect,
//! like addition and substraction.
//!
//! # Delays and timeouts
//!
//! [`Timer`] allows performing async delays. [`Ticker`] allows periodic delays without drifting over time.
//!
//! An implementation of the `embedded-hal` delay traits is provided by [`Delay`], for compatibility
//! with libraries from the ecosystem.
//!
//! # Wall-clock time
//!
//! The `time` module deals exclusively with a monotonically increasing tick count.
//! Therefore it has no direct support for wall-clock time ("real life" datetimes
//! like `2021-08-24 13:33:21`).
//!
//! If persistence across reboots is not needed, support can be built on top of
//! `embassy_time` by storing the offset between "seconds elapsed since boot"
//! and "seconds since unix epoch".
//!
//! # Time driver
//!
//! The `time` module is backed by a global "time driver" specified at build time.
//! Only one driver can be active in a program.
//!
//! All methods and structs transparently call into the active driver. This makes it
//! possible for libraries to use `embassy_time` in a driver-agnostic way without
//! requiring generic parameters.
//!
//! For more details, check the [`driver`] module.
// This mod MUST go first, so that the others see its macros.
pub(crate) mod fmt;