Add 64-bit rtc driver with alarm support.

examples/src/bin/rtc_raw.rs

@@ -0,0 +1,55 @@
+#![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 nrf52840_hal::clocks;
+
+static mut RTC: MaybeUninit<rtc::RTC<embassy_nrf::pac::RTC1>> = 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(rtc::RTC::new(p.RTC1));
+        &*ptr
+    };
+
+    rtc.start();
+    rtc.set_alarm(53719);
+
+    info!("initialized!");
+
+    let mut val = 0;
+    let mut printval = 0;
+    loop {
+        let val2 = rtc.now();
+        if val2 < val {
+            info!(
+                "timer ran backwards! {:u32} -> {:u32}",
+                val as u32, val2 as u32
+            );
+        }
+        val = val2;
+
+        if val > printval + 32768 {
+            info!("tick {:u32}", val as u32);
+            printval = val;
+        }
+    }
+}