From aafc925231e98e9c1fe5fd33ea4705bf84f30522 Mon Sep 17 00:00:00 2001
From: dcz <gilapfco.dcz@porcupinefactory.org>
Date: Sat, 20 Sep 2025 13:53:35 +0200
Subject: [PATCH 1/2] example: Explain clearing interrupt flags

---
 examples/interrupt.rs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/examples/interrupt.rs b/examples/interrupt.rs
index d39bf34..375f8ec 100644
--- a/examples/interrupt.rs
+++ b/examples/interrupt.rs
@@ -59,6 +59,7 @@ fn main() -> ! {
 fn TIMER1() {
     unsafe {
         if let Some(timer1) = G_TIMER1.as_mut() {
+            // If the interrupt flag is not cleared, the interrupt will get issued again immediately.
             timer1.clear_update_interrupt_flag();
         }
         if let Some(led) = R_LED.as_mut() {
@@ -69,4 +70,4 @@ fn TIMER1() {
             }
         }
     }
-}
\ No newline at end of file
+}

From f6872e6a790eebd1b040657746af9ceef5d9d712 Mon Sep 17 00:00:00 2001
From: dcz <gilapfco.dcz@porcupinefactory.org>
Date: Sat, 20 Sep 2025 14:23:52 +0200
Subject: [PATCH 2/2] examples: Add exti pin interrupt

---
 Cargo.toml                |  3 +-
 examples/interrupt_pin.rs | 88 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 90 insertions(+), 1 deletion(-)
 create mode 100644 examples/interrupt_pin.rs

diff --git a/Cargo.toml b/Cargo.toml
index 6500fd0..c7f5634 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -18,11 +18,12 @@ default-target = "x86_64-unknown-linux-gnu"
 gd32vf103xx-hal = "0.5.0"
 embedded-hal = "0.2.6"
 nb = "1.0.0"
-riscv = "0.10.1"
+riscv = {version = "0.10.1", features = ["critical-section-single-hart"]}
 st7735-lcd = { version = "0.8.1", optional = true }
 embedded-sdmmc = { version = "0.3.0", optional = true }
 
 [dev-dependencies]
+critical-section = "1.2"
 riscv-rt = "0.11.0"
 panic-halt = "0.2.0"
 embedded-graphics = "0.7.1"
diff --git a/examples/interrupt_pin.rs b/examples/interrupt_pin.rs
new file mode 100644
index 0000000..6010211
--- /dev/null
+++ b/examples/interrupt_pin.rs
@@ -0,0 +1,88 @@
+/*! This example demonstrates how to interrupt on pin state change.
+
+The LED will toggle every time the PB9 pin is shorted (without debouncing).
+*/
+
+#![no_std]
+#![no_main]
+use core::cell::RefCell;
+use critical_section::{self, Mutex};
+use gd32vf103xx_hal::{exti::{Exti, ExtiLine, TriggerEdge}, pac::Interrupt};
+use panic_halt as _;
+use longan_nano::hal::{pac, prelude::*, pac::*, eclic::*};
+use longan_nano::led::{rgb, Led, RED};
+use riscv_rt::entry;
+
+static R_LED: Mutex<RefCell<Option<RED>>> = Mutex::new(RefCell::new(None));
+
+#[entry]
+fn main() -> ! {
+    let dp = pac::Peripherals::take().unwrap();
+    let mut rcu = dp
+        .RCU
+        .configure()
+        .ext_hf_clock(8.mhz())
+        .sysclk(108.mhz())
+        .freeze();
+
+    let gpioa = dp.GPIOA.split(&mut rcu);
+    let gpiob = dp.GPIOB.split(&mut rcu);
+    let gpioc = dp.GPIOC.split(&mut rcu);
+
+    let (mut red, mut green, mut blue) = rgb(gpioc.pc13, gpioa.pa1, gpioa.pa2);
+    red.off();
+    green.off();
+    blue.off();
+
+    critical_section::with(|cs|
+        R_LED.borrow(cs).replace(Some(red))
+    );
+
+    // Make sure the pin is high when not shorted. A floating pin would keep flipping.
+    let butb8 = gpiob.pb8.into_pull_up_input();
+
+    // Configure external interrupts which feed into the interrupt controller
+    let mut exti = Exti::new(dp.EXTI);
+    let extiline = ExtiLine::from_gpio_line(butb8.pin_number()).unwrap();
+    exti.listen(extiline, TriggerEdge::Falling);
+
+    // Connect the pin to the external interrupt line
+    let mut afio = dp.AFIO.constrain(&mut rcu);
+    afio.extiss(gd32vf103xx_hal::gpio::Port::PBx, 8);
+
+    // Configure the interrupt controller
+    ECLIC::reset();
+    ECLIC::set_threshold_level(Level::L0);
+    ECLIC::set_level_priority_bits(LevelPriorityBits::L3P1);
+    ECLIC::setup(
+        Interrupt::EXTI_LINE9_5,
+        gd32vf103xx_hal::eclic::TriggerType::FallingEdge,
+        gd32vf103xx_hal::eclic::Level::L1,
+        gd32vf103xx_hal::eclic::Priority::P1,
+    );
+
+    unsafe {
+        ECLIC::unmask(Interrupt::EXTI_LINE9_5);
+        riscv::interrupt::enable();
+    };
+
+    loop { }
+}
+
+/// The interrupt handler.
+#[allow(non_snake_case)]
+#[no_mangle]
+fn EXTI_LINE9_5() {
+    // This handler is responsible for EXTI interrupt lines 5 to 9, but this example uses only one line, so there's no need to check which one has been triggered.
+    Exti::clear(ExtiLine::from_gpio_line(8).unwrap());
+
+    critical_section::with(|cs| {
+        if let Some(led) = R_LED.borrow(cs).borrow_mut().as_mut() {
+            if led.is_on() {
+                led.off();
+            } else {
+                led.on();
+            }
+        }
+    })
+}