Trait rtic::Monotonic

pub trait Monotonic: Clock {
    const DISABLE_INTERRUPT_ON_EMPTY_QUEUE: bool;

    unsafe fn reset(&mut self);
    fn set_compare(&mut self, instant: &Instant<Self>);
    fn clear_compare_flag(&mut self);

    fn on_interrupt(&mut self) { ... }
    fn enable_timer(&mut self) { ... }
    fn disable_timer(&mut self) { ... }
}

A monotonic clock / counter definition.

Codegen extensions provided

The RTIC codegen will implement an infallible Monotonic::now() that simply gets the value from the Clock::try_now(), and an Monotonic::zero() which returns the zero time for use in #[init].

Correctness

When implementing this trait it is important to decide if one want to have a fixed baseline and utilize the reset method. If not, one can implement reset as an empty method. If reset is not empty, it is not allowed for try_now()/now() to return nonsensical values if called before reset is invoked by the runtime. Therefore implementation authors should have methods in place for making sure of this, for example a flag in the timer which tracks if the reset method has been called yet, and if not always return 0.

The embedded_time::Clock implementation must be infallible.

Associated Constants

const DISABLE_INTERRUPT_ON_EMPTY_QUEUE: bool

This tells RTIC if it should disable the interrupt bound to the monotonic if there are no scheduled tasks. One may want to set this to false if one is using the on_interrupt method to perform housekeeping and need overflow interrupts to happen, such as when extending a 16 bit timer to 32/64 bits, even if there are no scheduled tasks.

Required methods

unsafe fn reset(&mut self)

Optionally resets the counter to zero for a fixed baseline in a system.

This method will be called exactly once by the RTIC runtime after #[init] returns and before tasks can start.

Correctness

The user may not call this method.

fn set_compare(&mut self, instant: &Instant<Self>)

Set the compare value of the timer interrupt.

fn clear_compare_flag(&mut self)

Clear the compare interrupt flag.

Provided methods

fn on_interrupt(&mut self)

Optional. Commonly used for performing housekeeping of a timer when it has been extended, e.g. a 16 bit timer extended to 32/64 bits. This will be called at the end of the interrupt handler after all other operations have finished.

fn enable_timer(&mut self)

Optional. This is used to save power, this is called when the Monotonic interrupt is enabled.

fn disable_timer(&mut self)

Optional. This is used to save power, this is called when the Monotonic interrupt is disabled.

Implementors