Struct Lptim1Rtc

pub struct Lptim1Rtc { /* private fields */ }

A low-level Real Time Clock with alarms implemented with the LPTIM1 peripheral.

Note: call handle_interrupt in the LPTIM1 interrupt.

Uses the LSI to yield a 32Khz operating speed. Uses 16 bit time segments to create 32 bit time at 32Khz, yielding a total operating time of 1.5 days. The time will wrap around when saturated, but care must be taken to properly wrap around deadlines as well. Currently wrapped around deadlines will trigger immediately. During the lifetime of this timer 3 interrupts will be triggered:

• ARR, once the 16 bit internal counter wraps around.
• CMP, to handle deadlines.
• CMPOK, when new deadlines have been uploaded to the timer.

You can extend the 1.5 days operating time by either making time an U64, or by adjusting the prescaler or source clock to a lower operating frequency.

Operates fine with the STOP2 sleep mode.

Implementations

impl Lptim1Rtc

pub fn new(timer: LPTIM1, rcc: &RCC) -> Self

Set up the heartbeat timer and interrupt.

Wakes the CPU at least every 2 seconds to update the time, and more often when necessary. Enables casually running sleep or stop2 whilst using async delays.

pub fn start_timer(&mut self)

Start the timer, starting with fraction count.

We will expect a CMPOK interrupt soon after this call. Hence make sure that the handle_interrupt is already callable from the interrupt when calling start_timer.

pub fn get_time(&self) -> u32

Get the current time.

pub fn set_alarm(&mut self, deadline: u32) -> Result<(), DeadlinePassed>

Set the alarm for some time on or after a specific deadline.

pub fn clear_alarm(&mut self)

Clear the alarm, regardless of being set.

pub fn handle_interrupt(&mut self) -> bool

Handle LPTIM1 interrupt, both to update time and a signal a possible alarm.

Returns whether an alarm was triggered. Needs to be run in interrupt-free context.

pub fn get_fraction(&self) -> u32

Get a fraction from 0x0000 to 0xFFFF relative to time.

Trait Implementations

impl Drop for Lptim1Rtc

fn drop(&mut self)

Executes the destructor for this type.

impl Timer for Lptim1Rtc

const DELTA: Self::Duration = {transmute(0x00000002): <impls::stm32l4x6_lptim1::Lptim1Rtc as Timer>::Duration}

A minimal time increment, i.e. the time it takes to execute a handful of instructions.

type Instant = InstantU32

A moment in time.

type Duration = DurationU32

A length of time.

fn reset(&mut self)

Initialize the clock and start counting.

fn interrupt_free<F: FnOnce(&CriticalSection) -> R, R>(f: F) -> R

Execute the function in an interrupt free critical section.

fn now(&self) -> Self::Instant

Yield the current time.

fn disarm(&mut self)

Disarm the set alarm.

fn arm(&mut self, deadline: &Self::Instant)

Set the alarm for a given time.