Merge pull request #4216 from 1-rafael-1/rp2040-rtc-alarm

embassy-rp (rp2040): Rtc wait_for_alarm

Author: lulf

embassy-rp/CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Add PIO SPI
 - Add PIO I2S input
 - Add PIO onewire parasite power strong pullup
+- add `wait_for_alarm` and `alarm_scheduled` methods to rtc module ([#4216](https://github.com/embassy-rs/embassy/pull/4216))
 
 ## 0.8.0 - 2025-08-26
 
@@ -55,7 +56,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## 0.4.0 - 2025-03-09
 
-- Add PIO functions. ([#3857](https://github.com/embassy-rs/embassy/pull/3857))  
+- Add PIO functions. ([#3857](https://github.com/embassy-rs/embassy/pull/3857))
   The functions added in this change are `get_addr` `get_tx_threshold`, `set_tx_threshold`, `get_rx_threshold`, `set_rx_threshold`, `set_thresholds`.
 - Expose the watchdog reset reason. ([#3877](https://github.com/embassy-rs/embassy/pull/3877))
 - Update pio-rs, reexport, move instr methods to SM. ([#3865](https://github.com/embassy-rs/embassy/pull/3865))
@@ -96,7 +97,7 @@ Small release fixing a few gnarly bugs, upgrading is strongly recommended.
 - Add Clone and Copy to Error types
 - fix spinlocks staying locked after reset.
 - wait until read matches for PSM accesses.
-- Remove generics 
+- Remove generics
 - fix drop implementation of BufferedUartRx and BufferedUartTx
 - implement `embedded_storage_async::nor_flash::MultiwriteNorFlash`
 - rp usb: wake ep-wakers after stalling

embassy-rp/src/rtc/datetime_no_deps.rs

@@ -46,6 +46,7 @@ pub struct DateTime {
 /// A day of the week
 #[repr(u8)]
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Ord, PartialOrd, Hash)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[allow(missing_docs)]
 pub enum DayOfWeek {
     Sunday = 0,

embassy-rp/src/rtc/filter.rs

@@ -4,7 +4,8 @@ use crate::pac::rtc::regs::{IrqSetup0, IrqSetup1};
 /// A filter used for [`RealTimeClock::schedule_alarm`].
 ///
 /// [`RealTimeClock::schedule_alarm`]: struct.RealTimeClock.html#method.schedule_alarm
-#[derive(Default)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Default)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct DateTimeFilter {
     /// The year that this alarm should trigger on, `None` if the RTC alarm should not trigger on a year value.
     pub year: Option<u16>,

embassy-rp/src/rtc/mod.rs

@@ -1,7 +1,12 @@
 //! RTC driver.
 mod filter;
 
+use core::future::poll_fn;
+use core::sync::atomic::{compiler_fence, AtomicBool, Ordering};
+use core::task::Poll;
+
 use embassy_hal_internal::{Peri, PeripheralType};
+use embassy_sync::waitqueue::AtomicWaker;
 
 pub use self::filter::DateTimeFilter;
 
@@ -11,6 +16,13 @@ mod datetime;
 
 pub use self::datetime::{DateTime, DayOfWeek, Error as DateTimeError};
 use crate::clocks::clk_rtc_freq;
+use crate::interrupt::typelevel::Binding;
+use crate::interrupt::{self, InterruptExt};
+
+// Static waker for the interrupt handler
+static WAKER: AtomicWaker = AtomicWaker::new();
+// Static flag to indicate if an alarm has occurred
+static ALARM_OCCURRED: AtomicBool = AtomicBool::new(false);
 
 /// A reference to the real time clock of the system
 pub struct Rtc<'d, T: Instance> {
@@ -23,10 +35,15 @@ impl<'d, T: Instance> Rtc<'d, T> {
     /// # Errors
     ///
     /// Will return `RtcError::InvalidDateTime` if the datetime is not a valid range.
-    pub fn new(inner: Peri<'d, T>) -> Self {
+    pub fn new(inner: Peri<'d, T>, _irq: impl Binding<interrupt::typelevel::RTC_IRQ, InterruptHandler>) -> Self {
         // Set the RTC divider
         inner.regs().clkdiv_m1().write(|w| w.set_clkdiv_m1(clk_rtc_freq() - 1));
 
+        // Setup the IRQ
+        // Clear any pending interrupts from the RTC_IRQ interrupt and enable it, so we do not have unexpected interrupts after initialization
+        interrupt::RTC_IRQ.unpend();
+        unsafe { interrupt::RTC_IRQ.enable() };
+
         Self { inner }
     }
 
@@ -174,6 +191,110 @@ impl<'d, T: Instance> Rtc<'d, T> {
     pub fn clear_interrupt(&mut self) {
         self.disable_alarm();
     }
+
+    /// Check if an alarm is scheduled.
+    ///
+    /// This function checks if the RTC alarm is currently active. If it is, it returns the alarm configuration
+    /// as a [`DateTimeFilter`]. Otherwise, it returns `None`.
+    pub fn alarm_scheduled(&self) -> Option<DateTimeFilter> {
+        // Check if alarm is active
+        if !self.inner.regs().irq_setup_0().read().match_active() {
+            return None;
+        }
+
+        // Get values from both alarm registers
+        let irq_0 = self.inner.regs().irq_setup_0().read();
+        let irq_1 = self.inner.regs().irq_setup_1().read();
+
+        // Create a DateTimeFilter and populate it based on which fields are enabled
+        let mut filter = DateTimeFilter::default();
+
+        if irq_0.year_ena() {
+            filter.year = Some(irq_0.year());
+        }
+
+        if irq_0.month_ena() {
+            filter.month = Some(irq_0.month());
+        }
+
+        if irq_0.day_ena() {
+            filter.day = Some(irq_0.day());
+        }
+
+        if irq_1.dotw_ena() {
+            // Convert day of week value to DayOfWeek enum
+            let day_of_week = match irq_1.dotw() {
+                0 => DayOfWeek::Sunday,
+                1 => DayOfWeek::Monday,
+                2 => DayOfWeek::Tuesday,
+                3 => DayOfWeek::Wednesday,
+                4 => DayOfWeek::Thursday,
+                5 => DayOfWeek::Friday,
+                6 => DayOfWeek::Saturday,
+                _ => return None, // Invalid day of week
+            };
+            filter.day_of_week = Some(day_of_week);
+        }
+
+        if irq_1.hour_ena() {
+            filter.hour = Some(irq_1.hour());
+        }
+
+        if irq_1.min_ena() {
+            filter.minute = Some(irq_1.min());
+        }
+
+        if irq_1.sec_ena() {
+            filter.second = Some(irq_1.sec());
+        }
+
+        Some(filter)
+    }
+
+    /// Wait for an RTC alarm to trigger.
+    ///
+    /// This function will wait until the RTC alarm is triggered. If the alarm is already triggered, it will return immediately.
+    /// If no alarm is scheduled, it will wait indefinitely until one is scheduled and triggered.
+    pub async fn wait_for_alarm(&mut self) {
+        poll_fn(|cx| {
+            WAKER.register(cx.waker());
+
+            // Atomically check and clear the alarm occurred flag to prevent race conditions
+            if critical_section::with(|_| {
+                let occurred = ALARM_OCCURRED.load(Ordering::SeqCst);
+                if occurred {
+                    ALARM_OCCURRED.store(false, Ordering::SeqCst);
+                }
+                occurred
+            }) {
+                // Clear the interrupt and disable the alarm
+                self.clear_interrupt();
+
+                compiler_fence(Ordering::SeqCst);
+                return Poll::Ready(());
+            } else {
+                return Poll::Pending;
+            }
+        })
+        .await;
+    }
+}
+
+/// Interrupt handler.
+pub struct InterruptHandler {
+    _empty: (),
+}
+
+impl crate::interrupt::typelevel::Handler<crate::interrupt::typelevel::RTC_IRQ> for InterruptHandler {
+    unsafe fn on_interrupt() {
+        // Disable the alarm first thing, to prevent unexpected re-entry
+        let rtc = crate::pac::RTC;
+        rtc.irq_setup_0().modify(|w| w.set_match_ena(false));
+
+        // Set the alarm occurred flag and wake the waker
+        ALARM_OCCURRED.store(true, Ordering::SeqCst);
+        WAKER.wake();
+    }
 }
 
 /// Errors that can occur on methods on [Rtc]

examples/rp/src/bin/rtc.rs

@@ -5,16 +5,22 @@
 
 use defmt::*;
 use embassy_executor::Spawner;
+use embassy_rp::bind_interrupts;
 use embassy_rp::rtc::{DateTime, DayOfWeek, Rtc};
 use embassy_time::Timer;
 use {defmt_rtt as _, panic_probe as _};
 
+// Bind the RTC interrupt to the handler
+bind_interrupts!(struct Irqs {
+    RTC_IRQ => embassy_rp::rtc::InterruptHandler;
+});
+
 #[embassy_executor::main]
 async fn main(_spawner: Spawner) {
     let p = embassy_rp::init(Default::default());
     info!("Wait for 20s");
 
-    let mut rtc = Rtc::new(p.RTC);
+    let mut rtc = Rtc::new(p.RTC, Irqs);
 
     if !rtc.is_running() {
         info!("Start RTC");

examples/rp/src/bin/rtc_alarm.rs

@@ -0,0 +1,66 @@
+//! This example shows how to use RTC (Real Time Clock) for scheduling alarms and reacting to them.
+
+#![no_std]
+#![no_main]
+
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_futures::select::{select, Either};
+use embassy_rp::bind_interrupts;
+use embassy_rp::rtc::{DateTime, DateTimeFilter, DayOfWeek, Rtc};
+use embassy_time::Timer;
+use {defmt_rtt as _, panic_probe as _};
+
+// Bind the RTC interrupt to the handler
+bind_interrupts!(struct Irqs {
+    RTC_IRQ => embassy_rp::rtc::InterruptHandler;
+});
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    let p = embassy_rp::init(Default::default());
+    let mut rtc = Rtc::new(p.RTC, Irqs);
+
+    if !rtc.is_running() {
+        info!("Start RTC");
+        let now = DateTime {
+            year: 2000,
+            month: 1,
+            day: 1,
+            day_of_week: DayOfWeek::Saturday,
+            hour: 0,
+            minute: 0,
+            second: 0,
+        };
+        rtc.set_datetime(now).unwrap();
+    }
+
+    loop {
+        // Wait for 5 seconds or until the alarm is triggered
+        match select(Timer::after_secs(5), rtc.wait_for_alarm()).await {
+            // Timer expired
+            Either::First(_) => {
+                let dt = rtc.now().unwrap();
+                info!(
+                    "Now: {}-{:02}-{:02} {}:{:02}:{:02}",
+                    dt.year, dt.month, dt.day, dt.hour, dt.minute, dt.second,
+                );
+
+                // See if the alarm is already scheduled, if not, schedule it
+                if rtc.alarm_scheduled().is_none() {
+                    info!("Scheduling alarm for 30 seconds from now");
+                    rtc.schedule_alarm(DateTimeFilter::default().second((dt.second + 30) % 60));
+                    info!("Alarm scheduled: {}", rtc.alarm_scheduled().unwrap());
+                }
+            }
+            // Alarm triggered
+            Either::Second(_) => {
+                let dt = rtc.now().unwrap();
+                info!(
+                    "ALARM TRIGGERED! Now: {}-{:02}-{:02} {}:{:02}:{:02}",
+                    dt.year, dt.month, dt.day, dt.hour, dt.minute, dt.second,
+                );
+            }
+        }
+    }
+}

tests/rp/Cargo.toml

@@ -64,6 +64,12 @@ name = "float"
 path = "src/bin/float.rs"
 required-features = [ "rp2040",]
 
+# RTC is only available on RP2040
+[[bin]]
+name = "rtc"
+path = "src/bin/rtc.rs"
+required-features = [ "rp2040",]
+
 [profile.dev]
 debug = 2
 debug-assertions = true