rtic_monotonics/nrf/rtc.rs
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//! [`Monotonic`](rtic_time::Monotonic) implementation for the nRF Real Time Clocks (RTC).
//!
//! # Example
//!
//! ```
//! use rtic_monotonics::nrf::rtc::prelude::*;
//! nrf_rtc0_monotonic!(Mono);
//!
//! fn init() {
//! # // This is normally provided by the selected PAC
//! # let rtc = unsafe { core::mem::transmute(()) };
//! // Start the monotonic
//! Mono::start(rtc);
//! }
//!
//! async fn usage() {
//! loop {
//! // Use the monotonic
//! let timestamp = Mono::now();
//! Mono::delay(100.millis()).await;
//! }
//! }
//! ```
/// Common definitions and traits for using the nRF RTC monotonics
pub mod prelude {
pub use crate::nrf_rtc0_monotonic;
pub use crate::nrf_rtc1_monotonic;
#[cfg(any(feature = "nrf52832", feature = "nrf52833", feature = "nrf52840"))]
pub use crate::nrf_rtc2_monotonic;
pub use crate::Monotonic;
pub use fugit::{self, ExtU64, ExtU64Ceil};
}
#[cfg(feature = "nrf52805")]
#[doc(hidden)]
pub use nrf52805_pac::{self as pac, RTC0, RTC1};
#[cfg(feature = "nrf52810")]
#[doc(hidden)]
pub use nrf52810_pac::{self as pac, RTC0, RTC1};
#[cfg(feature = "nrf52811")]
#[doc(hidden)]
pub use nrf52811_pac::{self as pac, RTC0, RTC1};
#[cfg(feature = "nrf52832")]
#[doc(hidden)]
pub use nrf52832_pac::{self as pac, RTC0, RTC1, RTC2};
#[cfg(feature = "nrf52833")]
#[doc(hidden)]
pub use nrf52833_pac::{self as pac, RTC0, RTC1, RTC2};
#[cfg(feature = "nrf52840")]
#[doc(hidden)]
pub use nrf52840_pac::{self as pac, RTC0, RTC1, RTC2};
#[cfg(feature = "nrf5340-app")]
#[doc(hidden)]
pub use nrf5340_app_pac::{self as pac, RTC0_NS as RTC0, RTC1_NS as RTC1};
#[cfg(feature = "nrf5340-net")]
#[doc(hidden)]
pub use nrf5340_net_pac::{self as pac, RTC0_NS as RTC0, RTC1_NS as RTC1};
#[cfg(feature = "nrf9160")]
#[doc(hidden)]
pub use nrf9160_pac::{self as pac, RTC0_NS as RTC0, RTC1_NS as RTC1};
use portable_atomic::{AtomicU32, Ordering};
use rtic_time::{
half_period_counter::calculate_now,
timer_queue::{TimerQueue, TimerQueueBackend},
};
#[doc(hidden)]
#[macro_export]
macro_rules! __internal_create_nrf_rtc_interrupt {
($mono_backend:ident, $rtc:ident) => {
#[no_mangle]
#[allow(non_snake_case)]
unsafe extern "C" fn $rtc() {
use $crate::TimerQueueBackend;
$crate::nrf::rtc::$mono_backend::timer_queue().on_monotonic_interrupt();
}
};
}
#[doc(hidden)]
#[macro_export]
macro_rules! __internal_create_nrf_rtc_struct {
($name:ident, $mono_backend:ident, $timer:ident) => {
/// A `Monotonic` based on the nRF RTC peripheral.
pub struct $name;
impl $name {
/// Starts the `Monotonic`.
///
/// This method must be called only once.
pub fn start(rtc: $crate::nrf::rtc::$timer) {
$crate::__internal_create_nrf_rtc_interrupt!($mono_backend, $timer);
$crate::nrf::rtc::$mono_backend::_start(rtc);
}
}
impl $crate::TimerQueueBasedMonotonic for $name {
type Backend = $crate::nrf::rtc::$mono_backend;
type Instant = $crate::fugit::Instant<
<Self::Backend as $crate::TimerQueueBackend>::Ticks,
1,
32_768,
>;
type Duration = $crate::fugit::Duration<
<Self::Backend as $crate::TimerQueueBackend>::Ticks,
1,
32_768,
>;
}
$crate::rtic_time::impl_embedded_hal_delay_fugit!($name);
$crate::rtic_time::impl_embedded_hal_async_delay_fugit!($name);
};
}
/// Create an RTC0 based monotonic and register the RTC0 interrupt for it.
///
/// See [`crate::nrf::rtc`] for more details.
#[macro_export]
macro_rules! nrf_rtc0_monotonic {
($name:ident) => {
$crate::__internal_create_nrf_rtc_struct!($name, Rtc0Backend, RTC0);
};
}
/// Create an RTC1 based monotonic and register the RTC1 interrupt for it.
///
/// See [`crate::nrf::rtc`] for more details.
#[macro_export]
macro_rules! nrf_rtc1_monotonic {
($name:ident) => {
$crate::__internal_create_nrf_rtc_struct!($name, Rtc1Backend, RTC1);
};
}
/// Create an RTC2 based monotonic and register the RTC2 interrupt for it.
///
/// See [`crate::nrf::rtc`] for more details.
#[cfg(any(feature = "nrf52832", feature = "nrf52833", feature = "nrf52840"))]
#[cfg_attr(
docsrs,
doc(cfg(any(feature = "nrf52832", feature = "nrf52833", feature = "nrf52840")))
)]
#[macro_export]
macro_rules! nrf_rtc2_monotonic {
($name:ident) => {
$crate::__internal_create_nrf_rtc_struct!($name, Rtc2Backend, RTC2);
};
}
struct TimerValueU24(u32);
impl rtic_time::half_period_counter::TimerValue for TimerValueU24 {
const BITS: u32 = 24;
}
impl From<TimerValueU24> for u64 {
fn from(value: TimerValueU24) -> Self {
Self::from(value.0)
}
}
macro_rules! make_rtc {
($backend_name:ident, $rtc:ident, $overflow:ident, $tq:ident$(, doc: ($($doc:tt)*))?) => {
/// RTC based [`TimerQueueBackend`].
$(
#[cfg_attr(docsrs, doc(cfg($($doc)*)))]
)?
pub struct $backend_name;
static $overflow: AtomicU32 = AtomicU32::new(0);
static $tq: TimerQueue<$backend_name> = TimerQueue::new();
impl $backend_name {
/// Starts the timer.
///
/// **Do not use this function directly.**
///
/// Use the prelude macros instead.
pub fn _start(rtc: $rtc) {
unsafe { rtc.prescaler.write(|w| w.bits(0)) };
// Disable interrupts, as preparation
rtc.intenclr.write(|w| w
.compare0().clear()
.compare1().clear()
.ovrflw().clear()
);
// Configure compare registers
rtc.cc[0].write(|w| unsafe { w.bits(0) }); // Dynamic wakeup
rtc.cc[1].write(|w| unsafe { w.bits(0x80_0000) }); // Half-period
// Timing critical, make sure we don't get interrupted
critical_section::with(|_|{
// Reset the timer
rtc.tasks_clear.write(|w| unsafe { w.bits(1) });
rtc.tasks_start.write(|w| unsafe { w.bits(1) });
// Clear pending events.
// Should be close enough to the timer reset that we don't miss any events.
rtc.events_ovrflw.write(|w| w);
rtc.events_compare[0].write(|w| w);
rtc.events_compare[1].write(|w| w);
// Make sure overflow counter is synced with the timer value
$overflow.store(0, Ordering::SeqCst);
// Initialized the timer queue
$tq.initialize(Self {});
// Enable interrupts.
// Should be close enough to the timer reset that we don't miss any events.
rtc.intenset.write(|w| w
.compare0().set()
.compare1().set()
.ovrflw().set()
);
rtc.evtenset.write(|w| w
.compare0().set()
.compare1().set()
.ovrflw().set()
);
});
// SAFETY: We take full ownership of the peripheral and interrupt vector,
// plus we are not using any external shared resources so we won't impact
// basepri/source masking based critical sections.
unsafe {
crate::set_monotonic_prio(pac::NVIC_PRIO_BITS, pac::Interrupt::$rtc);
pac::NVIC::unmask(pac::Interrupt::$rtc);
}
}
}
impl TimerQueueBackend for $backend_name {
type Ticks = u64;
fn now() -> Self::Ticks {
let rtc = unsafe { &*$rtc::PTR };
calculate_now(
|| $overflow.load(Ordering::Relaxed),
|| TimerValueU24(rtc.counter.read().bits())
)
}
fn on_interrupt() {
let rtc = unsafe { &*$rtc::PTR };
if rtc.events_ovrflw.read().bits() == 1 {
rtc.events_ovrflw.write(|w| unsafe { w.bits(0) });
let prev = $overflow.fetch_add(1, Ordering::Relaxed);
assert!(prev % 2 == 1, "Monotonic must have skipped an interrupt!");
}
if rtc.events_compare[1].read().bits() == 1 {
rtc.events_compare[1].write(|w| unsafe { w.bits(0) });
let prev = $overflow.fetch_add(1, Ordering::Relaxed);
assert!(prev % 2 == 0, "Monotonic must have skipped an interrupt!");
}
}
fn set_compare(mut instant: Self::Ticks) {
let rtc = unsafe { &*$rtc::PTR };
const MAX: u64 = 0xff_ffff;
// Disable interrupts because this section is timing critical.
// We rely on the fact that this entire section runs within one
// RTC clock tick. (which it will do easily if it doesn't get
// interrupted)
critical_section::with(|_|{
let now = Self::now();
// wrapping_sub deals with the u64 overflow corner case
let diff = instant.wrapping_sub(now);
let val = if diff <= MAX {
// Now we know `instant` whill happen within one `MAX` time duration.
// Errata: Timer interrupts don't fire if they are scheduled less than
// two ticks in the future. Make it three, because the timer could
// tick right now.
if diff < 3 {
instant = now.wrapping_add(3);
}
(instant & MAX) as u32
} else {
0
};
unsafe { rtc.cc[0].write(|w| w.bits(val)) };
});
}
fn clear_compare_flag() {
let rtc = unsafe { &*$rtc::PTR };
unsafe { rtc.events_compare[0].write(|w| w.bits(0)) };
}
fn pend_interrupt() {
pac::NVIC::pend(pac::Interrupt::$rtc);
}
fn timer_queue() -> &'static TimerQueue<Self> {
&$tq
}
}
};
}
make_rtc!(Rtc0Backend, RTC0, RTC0_OVERFLOWS, RTC0_TQ);
make_rtc!(Rtc1Backend, RTC1, RTC1_OVERFLOWS, RTC1_TQ);
#[cfg(any(feature = "nrf52832", feature = "nrf52833", feature = "nrf52840"))]
make_rtc!(Rtc2Backend, RTC2, RTC2_OVERFLOWS, RTC2_TQ, doc: (any(feature = "nrf52832", feature = "nrf52833", feature = "nrf52840")));