Merge pull request #4686 from robamu/add-nrf-rtc-driver

add basic RTC driver for nRF

17 files changed, 391 insertions, 1 deletions

diff --git a/embassy-nrf/CHANGELOG.md b/embassy-nrf/CHANGELOG.md
index 0cc1d56bb..0fedf9360 100644
--- a/embassy-nrf/CHANGELOG.md
+++ b/embassy-nrf/CHANGELOG.md
@@ -10,6 +10,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - changed: nrf54l: Disable glitch detection and enable DC/DC in init.
 - changed: Add embassy-net-driver-channel implementation for IEEE 802.15.4
+- changed: add persist() method for gpio and ppi
+- added: basic RTC driver
 - changed: add persist() method for gpio, gpiote, timer and ppi
 - changed: impl Drop for Timer
 
diff --git a/embassy-nrf/src/chips/nrf51.rs b/embassy-nrf/src/chips/nrf51.rs
index fd13ae5c4..3976e8ff0 100644
--- a/embassy-nrf/src/chips/nrf51.rs
+++ b/embassy-nrf/src/chips/nrf51.rs
@@ -8,6 +8,7 @@ pub const FLASH_SIZE: usize = 128 * 1024;
 embassy_hal_internal::peripherals! {
     // RTC
     RTC0,
+    #[cfg(not(feature = "time-driver-rtc1"))]
     RTC1,
 
     // WDT
@@ -110,6 +111,10 @@ impl_timer!(TIMER2, TIMER2, TIMER2);
 
 impl_rng!(RNG, RNG, RNG);
 
+impl_rtc!(RTC0, RTC0, RTC0);
+#[cfg(not(feature = "time-driver-rtc1"))]
+impl_rtc!(RTC1, RTC1, RTC1);
+
 impl_pin!(P0_00, 0, 0);
 impl_pin!(P0_01, 0, 1);
 impl_pin!(P0_02, 0, 2);
diff --git a/embassy-nrf/src/chips/nrf52805.rs b/embassy-nrf/src/chips/nrf52805.rs
index 7e72df8fc..63ba6999a 100644
--- a/embassy-nrf/src/chips/nrf52805.rs
+++ b/embassy-nrf/src/chips/nrf52805.rs
@@ -12,6 +12,7 @@ pub const APPROTECT_MIN_BUILD_CODE: u8 = b'B';
 embassy_hal_internal::peripherals! {
     // RTC
     RTC0,
+    #[cfg(not(feature="time-driver-rtc1"))]
     RTC1,
 
     // WDT
@@ -156,6 +157,10 @@ impl_timer!(TIMER0, TIMER0, TIMER0);
 impl_timer!(TIMER1, TIMER1, TIMER1);
 impl_timer!(TIMER2, TIMER2, TIMER2);
 
+impl_rtc!(RTC0, RTC0, RTC0);
+#[cfg(not(feature = "time-driver-rtc1"))]
+impl_rtc!(RTC1, RTC1, RTC1);
+
 impl_pin!(P0_00, 0, 0);
 impl_pin!(P0_01, 0, 1);
 impl_pin!(P0_02, 0, 2);
@@ -234,12 +239,12 @@ embassy_hal_internal::interrupt_mod!(
     TIMER0,
     TIMER1,
     TIMER2,
-    RTC0,
     TEMP,
     RNG,
     ECB,
     AAR_CCM,
     WDT,
+    RTC0,
     RTC1,
     QDEC,
     EGU0_SWI0,
diff --git a/embassy-nrf/src/chips/nrf52810.rs b/embassy-nrf/src/chips/nrf52810.rs
index e388e44e8..7f744f9fb 100644
--- a/embassy-nrf/src/chips/nrf52810.rs
+++ b/embassy-nrf/src/chips/nrf52810.rs
@@ -12,6 +12,7 @@ pub const APPROTECT_MIN_BUILD_CODE: u8 = b'E';
 embassy_hal_internal::peripherals! {
     // RTC
     RTC0,
+    #[cfg(not(feature="time-driver-rtc1"))]
     RTC1,
 
     // WDT
@@ -166,6 +167,10 @@ impl_timer!(TIMER0, TIMER0, TIMER0);
 impl_timer!(TIMER1, TIMER1, TIMER1);
 impl_timer!(TIMER2, TIMER2, TIMER2);
 
+impl_rtc!(RTC0, RTC0, RTC0);
+#[cfg(not(feature = "time-driver-rtc1"))]
+impl_rtc!(RTC1, RTC1, RTC1);
+
 impl_pin!(P0_00, 0, 0);
 impl_pin!(P0_01, 0, 1);
 impl_pin!(P0_02, 0, 2);
diff --git a/embassy-nrf/src/chips/nrf52811.rs b/embassy-nrf/src/chips/nrf52811.rs
index 96b8df30b..908167e31 100644
--- a/embassy-nrf/src/chips/nrf52811.rs
+++ b/embassy-nrf/src/chips/nrf52811.rs
@@ -12,6 +12,7 @@ pub const APPROTECT_MIN_BUILD_CODE: u8 = b'B';
 embassy_hal_internal::peripherals! {
     // RTC
     RTC0,
+    #[cfg(not(feature="time-driver-rtc1"))]
     RTC1,
 
     // WDT
@@ -168,6 +169,10 @@ impl_timer!(TIMER0, TIMER0, TIMER0);
 impl_timer!(TIMER1, TIMER1, TIMER1);
 impl_timer!(TIMER2, TIMER2, TIMER2);
 
+impl_rtc!(RTC0, RTC0, RTC0);
+#[cfg(not(feature = "time-driver-rtc1"))]
+impl_rtc!(RTC1, RTC1, RTC1);
+
 impl_pin!(P0_00, 0, 0);
 impl_pin!(P0_01, 0, 1);
 impl_pin!(P0_02, 0, 2);
diff --git a/embassy-nrf/src/chips/nrf52820.rs b/embassy-nrf/src/chips/nrf52820.rs
index ad461b153..22360575b 100644
--- a/embassy-nrf/src/chips/nrf52820.rs
+++ b/embassy-nrf/src/chips/nrf52820.rs
@@ -15,6 +15,7 @@ embassy_hal_internal::peripherals! {
 
     // RTC
     RTC0,
+    #[cfg(not(feature="time-driver-rtc1"))]
     RTC1,
 
     // WDT
@@ -164,6 +165,10 @@ impl_timer!(TIMER1, TIMER1, TIMER1);
 impl_timer!(TIMER2, TIMER2, TIMER2);
 impl_timer!(TIMER3, TIMER3, TIMER3, extended);
 
+impl_rtc!(RTC0, RTC0, RTC0);
+#[cfg(not(feature = "time-driver-rtc1"))]
+impl_rtc!(RTC1, RTC1, RTC1);
+
 impl_qdec!(QDEC, QDEC, QDEC);
 
 impl_rng!(RNG, RNG, RNG);
diff --git a/embassy-nrf/src/chips/nrf52832.rs b/embassy-nrf/src/chips/nrf52832.rs
index cf2abf23a..1598df3fe 100644
--- a/embassy-nrf/src/chips/nrf52832.rs
+++ b/embassy-nrf/src/chips/nrf52832.rs
@@ -16,6 +16,7 @@ pub const APPROTECT_MIN_BUILD_CODE: u8 = b'G';
 embassy_hal_internal::peripherals! {
     // RTC
     RTC0,
+    #[cfg(not(feature="time-driver-rtc1"))]
     RTC1,
     RTC2,
 
@@ -182,6 +183,11 @@ impl_twim!(TWISPI1, TWIM1, TWISPI1);
 impl_twis!(TWISPI0, TWIS0, TWISPI0);
 impl_twis!(TWISPI1, TWIS1, TWISPI1);
 
+impl_rtc!(RTC0, RTC0, RTC0);
+#[cfg(not(feature = "time-driver-rtc1"))]
+impl_rtc!(RTC1, RTC1, RTC1);
+impl_rtc!(RTC2, RTC2, RTC2);
+
 impl_pwm!(PWM0, PWM0, PWM0);
 impl_pwm!(PWM1, PWM1, PWM1);
 impl_pwm!(PWM2, PWM2, PWM2);
diff --git a/embassy-nrf/src/chips/nrf52833.rs b/embassy-nrf/src/chips/nrf52833.rs
index e46eb1d2b..6931fb064 100644
--- a/embassy-nrf/src/chips/nrf52833.rs
+++ b/embassy-nrf/src/chips/nrf52833.rs
@@ -15,6 +15,7 @@ embassy_hal_internal::peripherals! {
 
     // RTC
     RTC0,
+    #[cfg(not(feature = "time-driver-rtc1"))]
     RTC1,
     RTC2,
 
@@ -223,6 +224,11 @@ impl_timer!(TIMER2, TIMER2, TIMER2);
 impl_timer!(TIMER3, TIMER3, TIMER3, extended);
 impl_timer!(TIMER4, TIMER4, TIMER4, extended);
 
+impl_rtc!(RTC0, RTC0, RTC0);
+#[cfg(not(feature = "time-driver-rtc1"))]
+impl_rtc!(RTC1, RTC1, RTC1);
+impl_rtc!(RTC2, RTC2, RTC2);
+
 impl_pin!(P0_00, 0, 0);
 impl_pin!(P0_01, 0, 1);
 impl_pin!(P0_02, 0, 2);
diff --git a/embassy-nrf/src/chips/nrf52840.rs b/embassy-nrf/src/chips/nrf52840.rs
index 88747843d..5fa521aae 100644
--- a/embassy-nrf/src/chips/nrf52840.rs
+++ b/embassy-nrf/src/chips/nrf52840.rs
@@ -15,6 +15,7 @@ embassy_hal_internal::peripherals! {
 
     // RTC
     RTC0,
+    #[cfg(not(feature = "time-driver-rtc1"))]
     RTC1,
     RTC2,
 
@@ -220,6 +221,11 @@ impl_timer!(TIMER2, TIMER2, TIMER2);
 impl_timer!(TIMER3, TIMER3, TIMER3, extended);
 impl_timer!(TIMER4, TIMER4, TIMER4, extended);
 
+impl_rtc!(RTC0, RTC0, RTC0);
+#[cfg(not(feature = "time-driver-rtc1"))]
+impl_rtc!(RTC1, RTC1, RTC1);
+impl_rtc!(RTC2, RTC2, RTC2);
+
 impl_qspi!(QSPI, QSPI, QSPI);
 
 impl_pdm!(PDM, PDM, PDM);
diff --git a/embassy-nrf/src/chips/nrf5340_app.rs b/embassy-nrf/src/chips/nrf5340_app.rs
index c0290b7a4..730c9842d 100644
--- a/embassy-nrf/src/chips/nrf5340_app.rs
+++ b/embassy-nrf/src/chips/nrf5340_app.rs
@@ -168,6 +168,7 @@ embassy_hal_internal::peripherals! {
 
     // RTC
     RTC0,
+    #[cfg(not(feature = "time-driver-rtc1"))]
     RTC1,
 
     // WDT
@@ -369,6 +370,10 @@ impl_timer!(TIMER0, TIMER0, TIMER0);
 impl_timer!(TIMER1, TIMER1, TIMER1);
 impl_timer!(TIMER2, TIMER2, TIMER2);
 
+impl_rtc!(RTC0, RTC0, RTC0);
+#[cfg(not(feature = "time-driver-rtc1"))]
+impl_rtc!(RTC1, RTC1, RTC1);
+
 impl_qspi!(QSPI, QSPI, QSPI);
 
 impl_pdm!(PDM0, PDM0, PDM0);
diff --git a/embassy-nrf/src/chips/nrf5340_net.rs b/embassy-nrf/src/chips/nrf5340_net.rs
index d4c3e5353..413afc5c5 100644
--- a/embassy-nrf/src/chips/nrf5340_net.rs
+++ b/embassy-nrf/src/chips/nrf5340_net.rs
@@ -59,6 +59,7 @@ pub const FLASH_SIZE: usize = 256 * 1024;
 embassy_hal_internal::peripherals! {
     // RTC
     RTC0,
+    #[cfg(not(feature = "time-driver-rtc1"))]
     RTC1,
 
     // WDT
@@ -218,6 +219,10 @@ impl_timer!(TIMER0, TIMER0, TIMER0);
 impl_timer!(TIMER1, TIMER1, TIMER1);
 impl_timer!(TIMER2, TIMER2, TIMER2);
 
+impl_rtc!(RTC0, RTC0, RTC0);
+#[cfg(not(feature = "time-driver-rtc1"))]
+impl_rtc!(RTC1, RTC1, RTC1);
+
 impl_rng!(RNG, RNG, RNG);
 
 impl_pin!(P0_00, 0, 0);
diff --git a/embassy-nrf/src/chips/nrf9120.rs b/embassy-nrf/src/chips/nrf9120.rs
index e8ddbf86f..5aee19d97 100644
--- a/embassy-nrf/src/chips/nrf9120.rs
+++ b/embassy-nrf/src/chips/nrf9120.rs
@@ -131,6 +131,7 @@ pub const FLASH_SIZE: usize = 1024 * 1024;
 embassy_hal_internal::peripherals! {
     // RTC
     RTC0,
+    #[cfg(not(feature = "time-driver-rtc1"))]
     RTC1,
 
     // WDT
@@ -276,6 +277,10 @@ impl_timer!(TIMER0, TIMER0, TIMER0);
 impl_timer!(TIMER1, TIMER1, TIMER1);
 impl_timer!(TIMER2, TIMER2, TIMER2);
 
+impl_rtc!(RTC0, RTC0, RTC0);
+#[cfg(not(feature = "time-driver-rtc1"))]
+impl_rtc!(RTC1, RTC1, RTC1);
+
 impl_pin!(P0_00, 0, 0);
 impl_pin!(P0_01, 0, 1);
 impl_pin!(P0_02, 0, 2);
diff --git a/embassy-nrf/src/chips/nrf9160.rs b/embassy-nrf/src/chips/nrf9160.rs
index 5d04a72e5..64aec217c 100644
--- a/embassy-nrf/src/chips/nrf9160.rs
+++ b/embassy-nrf/src/chips/nrf9160.rs
@@ -131,6 +131,7 @@ pub const FLASH_SIZE: usize = 1024 * 1024;
 embassy_hal_internal::peripherals! {
     // RTC
     RTC0,
+    #[cfg(not(feature = "time-driver-rtc1"))]
     RTC1,
 
     // WDT
@@ -276,6 +277,10 @@ impl_timer!(TIMER0, TIMER0, TIMER0);
 impl_timer!(TIMER1, TIMER1, TIMER1);
 impl_timer!(TIMER2, TIMER2, TIMER2);
 
+impl_rtc!(RTC0, RTC0, RTC0);
+#[cfg(not(feature = "time-driver-rtc1"))]
+impl_rtc!(RTC1, RTC1, RTC1);
+
 impl_pin!(P0_00, 0, 0);
 impl_pin!(P0_01, 0, 1);
 impl_pin!(P0_02, 0, 2);
diff --git a/embassy-nrf/src/lib.rs b/embassy-nrf/src/lib.rs
index 897e660b8..e0847a312 100644
--- a/embassy-nrf/src/lib.rs
+++ b/embassy-nrf/src/lib.rs
@@ -155,6 +155,8 @@ pub mod reset;
 #[cfg(not(any(feature = "_nrf5340-app", feature = "_nrf91")))]
 pub mod rng;
 #[cfg(not(feature = "_nrf54l"))] // TODO
+pub mod rtc;
+#[cfg(not(feature = "_nrf54l"))] // TODO
 #[cfg(not(any(feature = "_nrf51", feature = "nrf52820", feature = "_nrf5340-net")))]
 pub mod saadc;
 #[cfg(not(feature = "_nrf54l"))] // TODO
diff --git a/embassy-nrf/src/rtc.rs b/embassy-nrf/src/rtc.rs
new file mode 100644
index 000000000..1a90d1e24
--- /dev/null
+++ b/embassy-nrf/src/rtc.rs
@@ -0,0 +1,265 @@
+//! Low-level RTC driver.
+
+#![macro_use]
+
+use embassy_hal_internal::{Peri, PeripheralType};
+
+use crate::chip::interrupt::typelevel::Interrupt as _;
+use crate::pac;
+
+/// Prescaler has an invalid value which exceeds 12 bits.
+#[derive(Debug, PartialEq, Eq)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct PrescalerOutOfRangeError(u32);
+
+/// Compare value has an invalid value which exceeds 24 bits.
+#[derive(Debug, PartialEq, Eq)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct CompareOutOfRangeError(u32);
+
+/// Interrupts/Events that can be generated by the RTCn peripheral.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub enum Interrupt {
+    /// Tick interrupt.
+    Tick,
+    /// Overflow interrupt.
+    Overflow,
+    /// Compare 0 interrupt.
+    Compare0,
+    /// Compare 1 interrupt.
+    Compare1,
+    /// Compare 2 interrupt.
+    Compare2,
+    /// Compare 3 interrupt. Only implemented for RTC1 and RTC2.
+    Compare3,
+}
+
+/// Compare registers available on the RTCn.
+#[derive(Debug, Copy, Clone)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub enum CompareChannel {
+    /// Channel 0
+    _0,
+    /// Channel 1
+    _1,
+    /// Channel 2
+    _2,
+    /// Channel 3. Only implemented for RTC1 and RTC2.
+    _3,
+}
+
+pub(crate) trait SealedInstance {
+    fn regs() -> pac::rtc::Rtc;
+}
+
+/// Basic RTC instance.
+#[allow(private_bounds)]
+pub trait Instance: SealedInstance + PeripheralType + 'static + Send {
+    /// Interrupt for this peripheral.
+    type Interrupt: crate::interrupt::typelevel::Interrupt;
+
+    /// Unsafely create a peripheral instance.
+    ///
+    /// # Safety
+    ///
+    /// Potentially allows to create multiple instances of the driver for the same peripheral
+    /// which can lead to undefined behavior.
+    unsafe fn steal() -> Peri<'static, Self>;
+}
+
+macro_rules! impl_rtc {
+    ($type:ident, $pac_type:ident, $irq:ident) => {
+        impl crate::rtc::SealedInstance for peripherals::$type {
+            #[inline]
+            fn regs() -> pac::rtc::Rtc {
+                unsafe { pac::rtc::Rtc::from_ptr(pac::$pac_type.as_ptr()) }
+            }
+        }
+
+        impl crate::rtc::Instance for peripherals::$type {
+            type Interrupt = crate::interrupt::typelevel::$irq;
+
+            unsafe fn steal() -> embassy_hal_internal::Peri<'static, Self> {
+                unsafe { peripherals::$type::steal() }
+            }
+        }
+    };
+}
+
+/// nRF RTC driver.
+pub struct Rtc<'d, T: Instance>(Peri<'d, T>);
+
+impl<'d, T: Instance> Rtc<'d, T> {
+    /// Create a new `Rtc` driver.
+    ///
+    /// fRTC \[Hz\] = 32_768 / (`prescaler` + 1 )
+    pub fn new(rtc: Peri<'d, T>, prescaler: u32) -> Result<Self, PrescalerOutOfRangeError> {
+        if prescaler >= (1 << 12) {
+            return Err(PrescalerOutOfRangeError(prescaler));
+        }
+
+        T::regs().prescaler().write(|w| w.set_prescaler(prescaler as u16));
+        Ok(Self(rtc))
+    }
+
+    /// Create a new `Rtc` driver, configuring it to run at the given frequency.
+    pub fn new_for_freq(rtc: Peri<'d, T>, freq_hz: u32) -> Result<Self, PrescalerOutOfRangeError> {
+        let prescaler = (32_768 / freq_hz).saturating_sub(1);
+        Self::new(rtc, prescaler)
+    }
+
+    /// Steal the RTC peripheral, without checking if it's already taken.
+    ///
+    /// # Safety
+    ///
+    /// Potentially allows to create multiple instances of the driver for the same peripheral
+    /// which can lead to undefined behavior.
+    pub unsafe fn steal() -> Self {
+        Self(unsafe { T::steal() })
+    }
+
+    /// Direct access to the RTC registers.
+    #[cfg(feature = "unstable-pac")]
+    #[inline]
+    pub fn regs(&mut self) -> pac::rtc::Rtc {
+        T::regs()
+    }
+
+    /// Enable the RTC.
+    #[inline]
+    pub fn enable(&mut self) {
+        T::regs().tasks_start().write_value(1);
+    }
+
+    /// Disable the RTC.
+    #[inline]
+    pub fn disable(&mut self) {
+        T::regs().tasks_stop().write_value(1);
+    }
+
+    /// Enables interrupts for the given [Interrupt] source.
+    ///
+    /// Optionally also enables the interrupt in the NVIC.
+    pub fn enable_interrupt(&mut self, int: Interrupt, enable_in_nvic: bool) {
+        let regs = T::regs();
+        match int {
+            Interrupt::Tick => regs.intenset().write(|w| w.set_tick(true)),
+            Interrupt::Overflow => regs.intenset().write(|w| w.set_ovrflw(true)),
+            Interrupt::Compare0 => regs.intenset().write(|w| w.set_compare(0, true)),
+            Interrupt::Compare1 => regs.intenset().write(|w| w.set_compare(1, true)),
+            Interrupt::Compare2 => regs.intenset().write(|w| w.set_compare(2, true)),
+            Interrupt::Compare3 => regs.intenset().write(|w| w.set_compare(3, true)),
+        }
+        if enable_in_nvic {
+            unsafe { T::Interrupt::enable() };
+        }
+    }
+
+    /// Disables interrupts for the given [Interrupt] source.
+    ///
+    /// Optionally also disables the interrupt in the NVIC.
+    pub fn disable_interrupt(&mut self, int: Interrupt, disable_in_nvic: bool) {
+        let regs = T::regs();
+        match int {
+            Interrupt::Tick => regs.intenclr().write(|w| w.set_tick(true)),
+            Interrupt::Overflow => regs.intenclr().write(|w| w.set_ovrflw(true)),
+            Interrupt::Compare0 => regs.intenclr().write(|w| w.set_compare(0, true)),
+            Interrupt::Compare1 => regs.intenclr().write(|w| w.set_compare(1, true)),
+            Interrupt::Compare2 => regs.intenclr().write(|w| w.set_compare(2, true)),
+            Interrupt::Compare3 => regs.intenclr().write(|w| w.set_compare(3, true)),
+        }
+        if disable_in_nvic {
+            T::Interrupt::disable();
+        }
+    }
+
+    /// Enable the generation of a hardware event from a given stimulus.
+    pub fn enable_event(&mut self, evt: Interrupt) {
+        let regs = T::regs();
+        match evt {
+            Interrupt::Tick => regs.evtenset().write(|w| w.set_tick(true)),
+            Interrupt::Overflow => regs.evtenset().write(|w| w.set_ovrflw(true)),
+            Interrupt::Compare0 => regs.evtenset().write(|w| w.set_compare(0, true)),
+            Interrupt::Compare1 => regs.evtenset().write(|w| w.set_compare(1, true)),
+            Interrupt::Compare2 => regs.evtenset().write(|w| w.set_compare(2, true)),
+            Interrupt::Compare3 => regs.evtenset().write(|w| w.set_compare(3, true)),
+        }
+    }
+
+    /// Disable the generation of a hardware event from a given stimulus.
+    pub fn disable_event(&mut self, evt: Interrupt) {
+        let regs = T::regs();
+        match evt {
+            Interrupt::Tick => regs.evtenclr().write(|w| w.set_tick(true)),
+            Interrupt::Overflow => regs.evtenclr().write(|w| w.set_ovrflw(true)),
+            Interrupt::Compare0 => regs.evtenclr().write(|w| w.set_compare(0, true)),
+            Interrupt::Compare1 => regs.evtenclr().write(|w| w.set_compare(1, true)),
+            Interrupt::Compare2 => regs.evtenclr().write(|w| w.set_compare(2, true)),
+            Interrupt::Compare3 => regs.evtenclr().write(|w| w.set_compare(3, true)),
+        }
+    }
+
+    /// Resets the given event.
+    pub fn reset_event(&mut self, evt: Interrupt) {
+        let regs = T::regs();
+        match evt {
+            Interrupt::Tick => regs.events_tick().write_value(0),
+            Interrupt::Overflow => regs.events_ovrflw().write_value(0),
+            Interrupt::Compare0 => regs.events_compare(0).write_value(0),
+            Interrupt::Compare1 => regs.events_compare(1).write_value(0),
+            Interrupt::Compare2 => regs.events_compare(2).write_value(0),
+            Interrupt::Compare3 => regs.events_compare(3).write_value(0),
+        }
+    }
+
+    /// Checks if the given event has been triggered.
+    pub fn is_event_triggered(&self, evt: Interrupt) -> bool {
+        let regs = T::regs();
+        let val = match evt {
+            Interrupt::Tick => regs.events_tick().read(),
+            Interrupt::Overflow => regs.events_ovrflw().read(),
+            Interrupt::Compare0 => regs.events_compare(0).read(),
+            Interrupt::Compare1 => regs.events_compare(1).read(),
+            Interrupt::Compare2 => regs.events_compare(2).read(),
+            Interrupt::Compare3 => regs.events_compare(3).read(),
+        };
+        val == 1
+    }
+
+    /// Set the compare value of a given register. The compare registers have a width
+    /// of 24 bits.
+    pub fn set_compare(&mut self, reg: CompareChannel, val: u32) -> Result<(), CompareOutOfRangeError> {
+        if val >= (1 << 24) {
+            return Err(CompareOutOfRangeError(val));
+        }
+
+        let reg = match reg {
+            CompareChannel::_0 => 0,
+            CompareChannel::_1 => 1,
+            CompareChannel::_2 => 2,
+            CompareChannel::_3 => 3,
+        };
+
+        T::regs().cc(reg).write(|w| w.set_compare(val));
+        Ok(())
+    }
+
+    /// Clear the Real Time Counter.
+    #[inline]
+    pub fn clear(&self) {
+        T::regs().tasks_clear().write_value(1);
+    }
+
+    /// Obtain the current value of the Real Time Counter, 24 bits of range.
+    #[inline]
+    pub fn read(&self) -> u32 {
+        T::regs().counter().read().counter()
+    }
+
+    /// Relase the RTC, returning the underlying peripheral instance.
+    #[inline]
+    pub fn release(self) -> Peri<'d, T> {
+        self.0
+    }
+}
diff --git a/examples/nrf52840/Cargo.toml b/examples/nrf52840/Cargo.toml
index 452e83b7e..ca3c6f863 100644
--- a/examples/nrf52840/Cargo.toml
+++ b/examples/nrf52840/Cargo.toml
@@ -35,6 +35,7 @@ embedded-hal-async = { version = "1.0" }
 embedded-hal-bus = { version = "0.1", features = ["async"] }
 num-integer = { version = "0.1.45", default-features = false }
 microfft = "0.5.0"
+portable-atomic = "1"
 
 [profile.release]
 debug = 2
diff --git a/examples/nrf52840/src/bin/rtc.rs b/examples/nrf52840/src/bin/rtc.rs
new file mode 100644
index 000000000..a3df7da14
--- /dev/null
+++ b/examples/nrf52840/src/bin/rtc.rs
@@ -0,0 +1,57 @@
+#![no_std]
+#![no_main]
+
+use core::cell::RefCell;
+
+use embassy_executor::Spawner;
+use embassy_nrf::gpio::{Level, Output, OutputDrive};
+use embassy_nrf::interrupt;
+use embassy_nrf::rtc::Rtc;
+use embassy_sync::blocking_mutex::raw::CriticalSectionRawMutex;
+use embassy_sync::blocking_mutex::Mutex;
+use portable_atomic::AtomicU64;
+use {defmt_rtt as _, panic_probe as _};
+
+// 64 bit counter which will never overflow.
+static TICK_COUNTER: AtomicU64 = AtomicU64::new(0);
+static RTC: Mutex<CriticalSectionRawMutex, RefCell<Option<Rtc<'static, embassy_nrf::peripherals::RTC0>>>> =
+    Mutex::new(RefCell::new(None));
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    defmt::println!("nRF52840 RTC example");
+    let p = embassy_nrf::init(Default::default());
+    let mut led = Output::new(p.P0_13, Level::High, OutputDrive::Standard);
+    // Counter resolution is 125 ms.
+    let mut rtc = Rtc::new(p.RTC0, (1 << 12) - 1).unwrap();
+    rtc.enable_interrupt(embassy_nrf::rtc::Interrupt::Tick, true);
+    rtc.enable_event(embassy_nrf::rtc::Interrupt::Tick);
+    rtc.enable();
+    RTC.lock(|r| {
+        let mut rtc_borrow = r.borrow_mut();
+        *rtc_borrow = Some(rtc);
+    });
+
+    let mut last_counter_val = 0;
+    loop {
+        let current = TICK_COUNTER.load(core::sync::atomic::Ordering::Relaxed);
+        if current != last_counter_val {
+            led.toggle();
+            last_counter_val = current;
+        }
+    }
+}
+
+#[interrupt]
+fn RTC0() {
+    // For 64-bit, we do not need to worry about overflowing, at least not for realistic program
+    // lifetimes.
+    TICK_COUNTER.fetch_add(1, core::sync::atomic::Ordering::Relaxed);
+    RTC.lock(|r| {
+        let mut rtc_borrow = r.borrow_mut();
+        rtc_borrow
+            .as_mut()
+            .unwrap()
+            .reset_event(embassy_nrf::rtc::Interrupt::Tick);
+    });
+}