emtick

This no_std Rust crate provides Instant and Duration types for time-related calculations with a focus on embedded systems.

emtick is greatly inspired by the embassy time module but uses generic clock sources to eleminate dependencies. It also allows the use of multiple optimized clock sources for performance reasons.

Usage Example

Provide a clock source by implementing the ClockTick trait on a type.

use emtick::ClockTick;

pub struct Clock1k;

impl ClockTick for Clock1k {
    const TICKS_PER_SECOND: u64 = 1000;

    fn ticks() -> u64 {
        systick::ticks()
    }
}

Create Instant and Duration types based on the clock source and use them for calculations.

use emtick::{delay::delay_until, Duration, Instant};

/// Create an instant with the current time.
let now = Instant::<Clock1k>::now();

/// Get the number of elapsed milliseconds since boot.
let millis = now.to_millis();

/// Create a duration of 5 seconds.
let duration = Duration::<Clock1k>::from_secs(5);

/// Calculate an instant in the future based on some duration.
let later = now + duration;

/// Sleep until an instant has elapsed.
delay_until(later);

Performance Considerations

emtick uses u64 ticks as base unit internally. While calculating time intervals via durations only use addition and subtraction instructions that are very fast on any platform, converting between ticks and natural time units (seconds, milliseconds, microseconds) have a performance impact. For that reason, it is recommened to minimize the amount of conversions.

In some cases conversion performance is optimized:

• When using a clock with 1kHz frequency (1ms pulse), all conversions between ticks and milliseconds are transparent.
• When using a clock with 1MHz frequency (1µs pulse), all conversions between ticks and microseconds are transparent.

Hint: if maximum performance is required for both milliseconds and microseconds conversions, use two separate optimized clock sources and create instants and durations with them appropriately.

Alternatives

• embedded-time
• fugit

License

Published under the MIT license. Any contribution to this project must be provided under the same license conditions.

Author: Oliver Rockstedt info@sourcebox.de