Add rtc_async example

examples/Cargo.toml

@@ -28,3 +28,4 @@ embassy = { version = "0.1.0", path = "../embassy" }
 embassy-nrf = { version = "0.1.0", path = "../embassy-nrf", features = ["defmt-trace", "52840"] }
 static-executor  = { version = "0.1.0", features=["defmt"]}
 futures = { version = "0.3.5", default-features = false }
+futures-intrusive = { version = "0.3.1", default-features = false }

examples/src/bin/rtc_async.rs

@@ -0,0 +1,88 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+#[path = "../example_common.rs"]
+mod example_common;
+use example_common::*;
+
+use core::mem::MaybeUninit;
+use cortex_m_rt::entry;
+use embassy_nrf::rtc;
+use futures_intrusive::timer::{Clock, LocalTimer, LocalTimerService};
+use nrf52840_hal::clocks;
+use static_executor::{task, Executor};
+
+struct RtcClock<T>(rtc::RTC<T>);
+
+impl<T: rtc::Instance> Clock for RtcClock<T> {
+    fn now(&self) -> u64 {
+        self.0.now()
+    }
+}
+
+#[task]
+async fn run1(rtc: &'static rtc::RTC<embassy_nrf::pac::RTC1>, timer: &'static LocalTimerService) {
+    loop {
+        info!("tick 1");
+        timer.deadline(rtc.now() + 64000).await;
+    }
+}
+
+#[task]
+async fn run2(rtc: &'static rtc::RTC<embassy_nrf::pac::RTC1>, timer: &'static LocalTimerService) {
+    loop {
+        info!("tick 2");
+        timer.deadline(rtc.now() + 23000).await;
+    }
+}
+
+static EXECUTOR: Executor = Executor::new(cortex_m::asm::sev);
+static mut RTC: MaybeUninit<RtcClock<embassy_nrf::pac::RTC1>> = MaybeUninit::uninit();
+static mut TIMER: MaybeUninit<LocalTimerService> = MaybeUninit::uninit();
+
+#[entry]
+fn main() -> ! {
+    info!("Hello World!");
+
+    let p = embassy_nrf::pac::Peripherals::take().dewrap();
+
+    clocks::Clocks::new(p.CLOCK)
+        .enable_ext_hfosc()
+        .set_lfclk_src_external(clocks::LfOscConfiguration::NoExternalNoBypass)
+        .start_lfclk();
+
+    let rtc: &'static _ = unsafe {
+        let ptr = RTC.as_mut_ptr();
+        ptr.write(RtcClock(rtc::RTC::new(p.RTC1)));
+        &*ptr
+    };
+
+    rtc.0.start();
+
+    let timer: &'static _ = unsafe {
+        let ptr = TIMER.as_mut_ptr();
+        ptr.write(LocalTimerService::new(rtc));
+        &*ptr
+    };
+
+    unsafe {
+        EXECUTOR.spawn(run1(&rtc.0, timer)).dewrap();
+        EXECUTOR.spawn(run2(&rtc.0, timer)).dewrap();
+
+        loop {
+            timer.check_expirations();
+
+            EXECUTOR.run();
+
+            match timer.next_expiration() {
+                // If this is in the past, set_alarm will immediately trigger the alarm,
+                // which will make the wfe immediately return so we do another loop iteration.
+                Some(at) => rtc.0.set_alarm(at, cortex_m::asm::sev),
+                None => rtc.0.clear_alarm(),
+            }
+
+            cortex_m::asm::wfe();
+        }
+    }
+}