Module systimer

System Timer (SYSTIMER)

Overview

The System Timer is a 52-bit timer which can be used, for example, to generate tick interrupts for an operating system, or simply as a general-purpose timer.

Configuration

The timer consists of two counters, UNIT0 and UNIT1. The counter values can be monitored by 3 comparators, COMP0, COMP1, and COMP2.

Alarms can be configured in two modes: Target (one-shot) and Periodic.

Examples

Splitting up the System Timer into three alarms

Use the split method to create three alarms from the System Timer, contained in a SysTimerAlarms struct.

use esp_hal::timer::systimer::{
    SystemTimer,
    Periodic,
};

let systimer = SystemTimer::new(
    peripherals.SYSTIMER,
).split::<Periodic>();

// Reconfigure a periodic alarm to be a target alarm
let target_alarm = systimer.alarm0.into_target();

General-purpose Timer

use esp_hal::timer::systimer::{
    Alarm,
    FrozenUnit,
    SpecificUnit,
    SystemTimer,
};

let mut systimer = SystemTimer::new(peripherals.SYSTIMER);

// Get the current tick count:
let now = SystemTimer::now();

let frozen_unit = FrozenUnit::new(&mut systimer.unit0);
let alarm0 = Alarm::new(systimer.comparator0, &frozen_unit);

alarm0.set_target(
    SystemTimer::now() + SystemTimer::ticks_per_second() * 2
);
alarm0.enable_interrupt(true);

while !alarm0.is_interrupt_set() {
    // Wait for the interrupt to be set
}

alarm0.clear_interrupt();

Modules

• etm
  Event Task Matrix Function

Structs

• Alarm
  A single alarm.
• AnyComparator
  Any Comparator. Could be either comparator 0, comparator 1, etc.
• AnyUnit
  Any Unit. Could be either unit 0 or unit 1.
• FrozenUnit
  A unit whose value cannot be updated.
• Periodic
  A marker for a Alarm in periodic mode.
• SpecificComparator
  A specific Comparator. i.e. Either comparator 0, comparator 1, etc.
• SpecificUnit
  A specific Unit. i.e. Either unit 0 or unit 1.
• SysTimerAlarms
  Alarms created from the System Timer peripheral.
• SystemTimer
  System Timer driver.
• Target
  A marker for a Alarm in target mode.

Enums

• ComparatorMode
  The modes of a comparator.
• UnitConfig
  The configuration of a unit.

Traits

• Comparator
  A comparator that can generate alarms/interrupts based on values of a unit.
• Unit
  A 52-bit counter.