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|
//! 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]
#![feature(type_alias_impl_trait)]
use cortex_m_rt::entry;
use defmt::{info, unwrap};
use embassy_executor::time::{Duration, Instant, Timer};
use embassy_nrf::executor::{Executor, InterruptExecutor};
use embassy_nrf::interrupt;
use embassy_nrf::interrupt::InterruptExt;
use embassy_util::Forever;
use {defmt_rtt as _, panic_probe as _};
#[embassy_executor::task]
async fn run_high() {
loop {
info!(" [high] tick!");
Timer::after(Duration::from_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(32_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(Duration::from_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(64_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(Duration::from_ticks(32983)).await;
}
}
static EXECUTOR_HIGH: Forever<InterruptExecutor<interrupt::SWI1_EGU1>> = Forever::new();
static EXECUTOR_MED: Forever<InterruptExecutor<interrupt::SWI0_EGU0>> = Forever::new();
static EXECUTOR_LOW: Forever<Executor> = Forever::new();
#[entry]
fn main() -> ! {
info!("Hello World!");
let _p = embassy_nrf::init(Default::default());
// High-priority executor: SWI1_EGU1, priority level 6
let irq = interrupt::take!(SWI1_EGU1);
irq.set_priority(interrupt::Priority::P6);
let executor = EXECUTOR_HIGH.put(InterruptExecutor::new(irq));
let spawner = executor.start();
unwrap!(spawner.spawn(run_high()));
// Medium-priority executor: SWI0_EGU0, priority level 7
let irq = interrupt::take!(SWI0_EGU0);
irq.set_priority(interrupt::Priority::P7);
let executor = EXECUTOR_MED.put(InterruptExecutor::new(irq));
let spawner = executor.start();
unwrap!(spawner.spawn(run_med()));
// Low priority executor: runs in thread mode, using WFE/SEV
let executor = EXECUTOR_LOW.put(Executor::new());
executor.run(|spawner| {
unwrap!(spawner.spawn(run_low()));
});
}
|
