add low-power example and hsem traces for #4092

Author: ckrenslehner

embassy-stm32/src/hsem/mod.rs

@@ -203,14 +203,31 @@ impl<'d, T: Instance> HardwareSemaphore<'d, T> {
     /// carried out from the HSEM_RLRx register.
     pub fn one_step_lock(&mut self, sem_id: SemId) -> Result<(), HsemError> {
         let reg = T::regs().rlr(sem_id.into()).read();
+        trace!(
+            "RLR (bits: 0x{:x}) - lock: {}, coreid: {}, procid: {}",
+            reg.0,
+            reg.lock(),
+            reg.coreid(),
+            reg.procid()
+        );
 
         match (
             reg.lock(),
             reg.coreid() == RlrCoreId::from(CoreId::get_current()) as u8,
             reg.procid(),
         ) {
-            (true, true, 0) => Ok(()),
-            _ => Err(HsemError::LockFailed),
+            (true, true, 0) => {
+                trace!(
+                    "Locked successfully (coreid: {}, procid: {})",
+                    reg.coreid(),
+                    reg.procid()
+                );
+                Ok(())
+            }
+            _ => {
+                trace!("Failed to lock (coreid: {}, procid: {})", reg.coreid(), reg.procid());
+                Err(HsemError::LockFailed)
+            }
         }
     }
 

examples/stm32wb/Cargo.toml

@@ -27,6 +27,7 @@ static_cell = "2"
 default = ["ble", "mac"]
 mac = ["embassy-stm32-wpan/mac", "dep:embassy-net"]
 ble = ["embassy-stm32-wpan/ble"]
+low-power = ["embassy-stm32/low-power"]
 
 [[bin]] 
 name = "tl_mbox_ble"
@@ -52,5 +53,9 @@ required-features = ["ble"]
 name = "gatt_server"
 required-features = ["ble"]
 
+[[bin]]
+name = "low_power"
+required-features = ["low-power"]
+
 [profile.release]
 debug = 2

examples/stm32wb/src/bin/low_power.rs

@@ -0,0 +1,50 @@
+#![no_std]
+#![no_main]
+
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_stm32::gpio::{Level, Output, Speed};
+use embassy_stm32::rtc::{Rtc, RtcConfig};
+use embassy_stm32::peripherals;
+use embassy_time::Timer;
+use {defmt_rtt as _, panic_probe as _};
+use static_cell::StaticCell;
+
+#[cortex_m_rt::entry]
+fn main() -> ! {
+    embassy_stm32::low_power::Executor::take().run(|spawner| {
+        spawner.spawn(async_main(spawner)).unwrap();
+    });
+}
+
+#[embassy_executor::task]
+async fn async_main(_spawner: Spawner) {
+    let mut config = embassy_stm32::Config::default();
+    // when enabled the power-consumption is much higher during stop, but debugging and RTT is working
+    config.enable_debug_during_sleep = true;
+    // Enable LSE and configure RTC to use LSE
+    config.rcc.ls = embassy_stm32::rcc::LsConfig::default_lse();
+    config.rcc.ls.rtc = embassy_stm32::rcc::RtcClockSource::LSE;
+    let p = embassy_stm32::init(config);
+
+    static RTC: StaticCell<Rtc> = StaticCell::new();
+    static HSEM: StaticCell<embassy_stm32::hsem::HardwareSemaphore<peripherals::HSEM>> = StaticCell::new();
+    let rtc = RTC.init(Rtc::new(p.RTC, RtcConfig::default()));
+    let hsem = HSEM.init(embassy_stm32::hsem::HardwareSemaphore::new(p.HSEM));
+
+    embassy_stm32::low_power::stop_with_rtc_and_hsem(rtc, hsem);
+
+    info!("Hello World!");
+
+    let mut led = Output::new(p.PB0, Level::High, Speed::Low);
+
+    loop {
+        info!("high");
+        led.set_high();
+        Timer::after_millis(1000).await;
+
+        info!("low");
+        led.set_low();
+        Timer::after_millis(1000).await;
+    }
+}