example/timer: Clear the interrupt flag

Author: maximeborges

examples/timer.rs

@@ -7,18 +7,23 @@
 extern crate panic_semihosting;
 
 use core::fmt::Write;
+use core::cell::{RefCell};
 
+use cortex_m::interrupt::{free, Mutex};
 use cortex_m_rt::entry;
 use cortex_m_semihosting::hio;
 
 use cortex_m::peripheral::NVIC;
 
 use stm32f7xx_hal::{
-    interrupt, pac,
+    interrupt,
+    pac::{self, TIM2},
     prelude::*,
     timer::{Event, Timer},
 };
 
+static TIMER: Mutex<RefCell<Option<Timer<TIM2>>>> = Mutex::new(RefCell::new(None));
+
 #[entry]
 fn main() -> ! {
     let mut hstdout = hio::hstdout().unwrap();
@@ -29,17 +34,27 @@ fn main() -> ! {
     let mut rcc = dp.RCC.constrain();
     let clocks = rcc.cfgr.freeze();
 
+    let mut timer = Timer::tim2(dp.TIM2, 1.Hz(), clocks, &mut rcc.apb1);
+    timer.listen(Event::TimeOut);
+
+    // Save information needed by the interrupt handler to the global variable
+    free(|cs| {
+        TIMER.borrow(cs).replace(Some(timer));
+    });
+
     unsafe {
         NVIC::unmask(pac::Interrupt::TIM2);
     }
-    let mut timer = Timer::tim2(dp.TIM2, 1.Hz(), clocks, &mut rcc.apb1);
-    timer.listen(Event::TimeOut);
 
     loop {}
 }
 
 #[interrupt]
 fn TIM2() {
+    free(|cs| {
+        TIMER.borrow(cs).borrow_mut().as_mut().unwrap().clear_interrupt(Event::TimeOut)
+    });
+
     let mut hstdout = hio::hstdout().unwrap();
     writeln!(hstdout, "TIM2 intr!").unwrap();
 }