Add multiprio example for stm32h7 inspired by stm32f4

2 files changed, 147 insertions, 2 deletions

diff --git a/examples/stm32h7/Cargo.toml b/examples/stm32h7/Cargo.toml
index d9ea2626d..84a89b378 100644
--- a/examples/stm32h7/Cargo.toml
+++ b/examples/stm32h7/Cargo.toml
@@ -6,9 +6,9 @@ license = "MIT OR Apache-2.0"
 
 [dependencies]
 # Change stm32h743bi to your chip name, if necessary.
-embassy-stm32 = { version = "0.1.0", path = "../../embassy-stm32", features = ["defmt", "stm32h743bi", "time-driver-any", "exti", "memory-x", "unstable-pac", "chrono"] }
+embassy-stm32 = { version = "0.1.0", path = "../../embassy-stm32", features = ["defmt", "stm32h743bi", "time-driver-tim2", "exti", "memory-x", "unstable-pac", "chrono"] }
 embassy-sync = { version = "0.5.0", path = "../../embassy-sync", features = ["defmt"] }
-embassy-executor = { version = "0.5.0", path = "../../embassy-executor", features = ["task-arena-size-32768", "arch-cortex-m", "executor-thread", "defmt", "integrated-timers"] }
+embassy-executor = { version = "0.5.0", path = "../../embassy-executor", features = ["task-arena-size-32768", "arch-cortex-m", "executor-thread", "executor-interrupt", "defmt", "integrated-timers"] }
 embassy-time = { version = "0.3.0", path = "../../embassy-time", features = ["defmt", "defmt-timestamp-uptime", "tick-hz-32_768"] }
 embassy-net = { version = "0.4.0", path = "../../embassy-net", features = ["defmt", "tcp", "dhcpv4", "medium-ethernet", "proto-ipv6", "dns"] }
 embassy-usb = { version = "0.1.0", path = "../../embassy-usb", features = ["defmt"] }
diff --git a/examples/stm32h7/src/bin/multiprio.rs b/examples/stm32h7/src/bin/multiprio.rs
new file mode 100644
index 000000000..73f8dd092
--- /dev/null
+++ b/examples/stm32h7/src/bin/multiprio.rs
@@ -0,0 +1,145 @@
+//! This example showcases how to create multiple Executor instances to run tasks at
+//! different priority levels.
+//!
+//! Low priority executor runs in thread mode (not interrupt), and uses `sev` for signaling
+//! there's work in the queue, and `wfe` for waiting for work.
+//!
+//! Medium and high priority executors run in two interrupts with different priorities.
+//! Signaling work is done by pending the interrupt. No "waiting" needs to be done explicitly, since
+//! when there's work the interrupt will trigger and run the executor.
+//!
+//! Sample output below. Note that high priority ticks can interrupt everything else, and
+//! medium priority computations can interrupt low priority computations, making them to appear
+//! to take significantly longer time.
+//!
+//! ```not_rust
+//!     [med] Starting long computation
+//!     [med] done in 992 ms
+//!         [high] tick!
+//! [low] Starting long computation
+//!     [med] Starting long computation
+//!         [high] tick!
+//!         [high] tick!
+//!     [med] done in 993 ms
+//!     [med] Starting long computation
+//!         [high] tick!
+//!         [high] tick!
+//!     [med] done in 993 ms
+//! [low] done in 3972 ms
+//!     [med] Starting long computation
+//!         [high] tick!
+//!         [high] tick!
+//!     [med] done in 993 ms
+//! ```
+//!
+//! For comparison, try changing the code so all 3 tasks get spawned on the low priority executor.
+//! You will get an output like the following. Note that no computation is ever interrupted.
+//!
+//! ```not_rust
+//!         [high] tick!
+//!     [med] Starting long computation
+//!     [med] done in 496 ms
+//! [low] Starting long computation
+//! [low] done in 992 ms
+//!     [med] Starting long computation
+//!     [med] done in 496 ms
+//!         [high] tick!
+//! [low] Starting long computation
+//! [low] done in 992 ms
+//!         [high] tick!
+//!     [med] Starting long computation
+//!     [med] done in 496 ms
+//!         [high] tick!
+//! ```
+//!
+
+#![no_std]
+#![no_main]
+
+use cortex_m_rt::entry;
+use defmt::*;
+use embassy_executor::{Executor, InterruptExecutor};
+use embassy_stm32::interrupt;
+use embassy_stm32::interrupt::{InterruptExt, Priority};
+use embassy_time::{Instant, Timer};
+use static_cell::StaticCell;
+use {defmt_rtt as _, panic_probe as _};
+
+#[embassy_executor::task]
+async fn run_high() {
+    loop {
+        info!("        [high] tick!");
+        Timer::after_ticks(27374).await;
+    }
+}
+
+#[embassy_executor::task]
+async fn run_med() {
+    loop {
+        let start = Instant::now();
+        info!("    [med] Starting long computation");
+
+        // Spin-wait to simulate a long CPU computation
+        cortex_m::asm::delay(128_000_000); // ~1 second
+
+        let end = Instant::now();
+        let ms = end.duration_since(start).as_ticks() / 33;
+        info!("    [med] done in {} ms", ms);
+
+        Timer::after_ticks(23421).await;
+    }
+}
+
+#[embassy_executor::task]
+async fn run_low() {
+    loop {
+        let start = Instant::now();
+        info!("[low] Starting long computation");
+
+        // Spin-wait to simulate a long CPU computation
+        cortex_m::asm::delay(256_000_000); // ~2 seconds
+
+        let end = Instant::now();
+        let ms = end.duration_since(start).as_ticks() / 33;
+        info!("[low] done in {} ms", ms);
+
+        Timer::after_ticks(32983).await;
+    }
+}
+
+static EXECUTOR_HIGH: InterruptExecutor = InterruptExecutor::new();
+static EXECUTOR_MED: InterruptExecutor = InterruptExecutor::new();
+static EXECUTOR_LOW: StaticCell<Executor> = StaticCell::new();
+
+#[interrupt]
+unsafe fn UART4() {
+    EXECUTOR_HIGH.on_interrupt()
+}
+
+#[interrupt]
+unsafe fn UART5() {
+    EXECUTOR_MED.on_interrupt()
+}
+
+#[entry]
+fn main() -> ! {
+    info!("Hello World!");
+
+    let _p = embassy_stm32::init(Default::default());
+
+    // High-priority executor: UART4, priority level 6
+    interrupt::UART4.set_priority(Priority::P6);
+    let spawner = EXECUTOR_HIGH.start(interrupt::UART4);
+    unwrap!(spawner.spawn(run_high()));
+
+    // Medium-priority executor: UART5, priority level 7
+    interrupt::UART5.set_priority(Priority::P7);
+    let spawner = EXECUTOR_MED.start(interrupt::UART5);
+    unwrap!(spawner.spawn(run_med()));
+
+    // Low priority executor: runs in thread mode, using WFE/SEV
+    let executor = EXECUTOR_LOW.init(Executor::new());
+    executor.run(|spawner| {
+        unwrap!(spawner.spawn(run_low()));
+    });
+}