added interrupt example

Author: seanybaggins

Cargo.toml

@@ -152,6 +152,10 @@ required-features = ["stm32f303xc"]
 name = "gpio_erased"
 required-features = ["rt", "stm32f303xc"]
 
+[[example]]
+name = "gpio_interrupts"
+required-features = ["rt", "stm32f303xc"]
+
 [[test]]
 name = "rcc"
 required-features = ["rt", "defmt"]

examples/gpio_interrupts.rs

@@ -0,0 +1,86 @@
+#![no_main]
+#![no_std]
+
+use panic_semihosting as _;
+
+use stm32f3xx_hal as hal;
+
+use core::cell::RefCell;
+use cortex_m::asm;
+use cortex_m::interrupt::Mutex;
+use cortex_m_rt::entry;
+use hal::gpio::{gpioa, gpioe, Edge, Input, Output, PushPull};
+use hal::interrupt;
+use hal::pac;
+use hal::pac::{Interrupt, NVIC};
+use hal::prelude::*;
+
+type LedPin = gpioe::PE9<Output<PushPull>>;
+static LED: Mutex<RefCell<Option<LedPin>>> = Mutex::new(RefCell::new(None));
+
+type ButtonPin = gpioa::PA0<Input>;
+static BUTTON: Mutex<RefCell<Option<ButtonPin>>> = Mutex::new(RefCell::new(None));
+
+// When the user button is pressed. The north LED with toggle.
+#[entry]
+fn main() -> ! {
+    // Getting access to registers we will need for configuration.
+    let device_peripherals = pac::Peripherals::take().unwrap();
+    let mut rcc = device_peripherals.RCC.constrain();
+    let mut syscfg = device_peripherals.SYSCFG.constrain(&mut rcc.apb2);
+    let mut exti = device_peripherals.EXTI;
+    let mut gpioe = device_peripherals.GPIOE.split(&mut rcc.ahb);
+    let mut gpioa = device_peripherals.GPIOA.split(&mut rcc.ahb);
+
+    let mut led = gpioe
+        .pe9
+        .into_push_pull_output(&mut gpioe.moder, &mut gpioe.otyper);
+    // Turn the led on so we know the configuration step occurred.
+    led.toggle().expect("unable to toggle led in configuration");
+
+    // Move the ownership of the led to the global LED
+    cortex_m::interrupt::free(|cs| *LED.borrow(cs).borrow_mut() = Some(led));
+
+    // Configuring the user button to trigger an interrupt when the button is pressed.
+    let mut user_button = gpioa
+        .pa0
+        .into_pull_down_input(&mut gpioa.moder, &mut gpioa.pupdr);
+    user_button.make_interrupt_source(&mut syscfg);
+    user_button.trigger_on_edge(&mut exti, Edge::Rising);
+    user_button.enable_interrupt(&mut exti);
+    // Moving ownership to the global BUTTON so we can clear the interrupt pending bit.
+    cortex_m::interrupt::free(|cs| *BUTTON.borrow(cs).borrow_mut() = Some(user_button));
+
+    unsafe { NVIC::unmask(Interrupt::EXTI0) };
+
+    loop {
+        asm::wfi();
+    }
+}
+
+// Button Pressed interrupt.
+// The exti# maps to the pin number that is being used as an external interrupt.
+// See page 295 of the stm32f303 reference manual for proof:
+// http://www.st.com/resource/en/reference_manual/dm00043574.pdf
+//
+// This may be called more than once per button press from the user since the button may not be debounced.
+#[interrupt]
+fn EXTI0() {
+    cortex_m::interrupt::free(|cs| {
+        // Toggle the LED
+        LED.borrow(cs)
+            .borrow_mut()
+            .as_mut()
+            .unwrap()
+            .toggle()
+            .unwrap();
+
+        // Clear the interrupt pending bit so we don't infinitely call this routine
+        BUTTON
+            .borrow(cs)
+            .borrow_mut()
+            .as_mut()
+            .unwrap()
+            .clear_interrupt_pending_bit();
+    })
+}