mirror of
https://github.com/embassy-rs/embassy.git
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95 lines
3.5 KiB
Rust
95 lines
3.5 KiB
Rust
//! This example shows how you can use raw interrupt handlers alongside embassy.
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//! The example also showcases some of the options available for sharing resources/data.
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//!
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//! In the example, an ADC reading is triggered every time the PWM wraps around.
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//! The sample data is sent down a channel, to be processed inside a low priority task.
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//! The processed data is then used to adjust the PWM duty cycle, once every second.
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#![no_std]
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#![no_main]
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use core::cell::{Cell, RefCell};
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use defmt::*;
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use embassy_executor::Spawner;
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use embassy_rp::adc::{self, Adc, Blocking};
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use embassy_rp::gpio::Pull;
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use embassy_rp::interrupt;
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use embassy_rp::pwm::{Config, Pwm};
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use embassy_sync::blocking_mutex::raw::CriticalSectionRawMutex;
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use embassy_sync::blocking_mutex::Mutex;
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use embassy_sync::channel::Channel;
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use embassy_time::{Duration, Ticker};
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use portable_atomic::{AtomicU32, Ordering};
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use static_cell::StaticCell;
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use {defmt_rtt as _, panic_probe as _};
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static COUNTER: AtomicU32 = AtomicU32::new(0);
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static PWM: Mutex<CriticalSectionRawMutex, RefCell<Option<Pwm>>> = Mutex::new(RefCell::new(None));
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static ADC: Mutex<CriticalSectionRawMutex, RefCell<Option<(Adc<Blocking>, adc::Channel)>>> =
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Mutex::new(RefCell::new(None));
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static ADC_VALUES: Channel<CriticalSectionRawMutex, u16, 2048> = Channel::new();
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#[embassy_executor::main]
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async fn main(spawner: Spawner) {
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embassy_rp::pac::SIO.spinlock(31).write_value(1);
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let p = embassy_rp::init(Default::default());
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let adc = Adc::new_blocking(p.ADC, Default::default());
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let p26 = adc::Channel::new_pin(p.PIN_26, Pull::None);
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ADC.lock(|a| a.borrow_mut().replace((adc, p26)));
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let pwm = Pwm::new_output_b(p.PWM_SLICE4, p.PIN_25, Default::default());
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PWM.lock(|p| p.borrow_mut().replace(pwm));
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// Enable the interrupt for pwm slice 4
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embassy_rp::pac::PWM.inte().modify(|w| w.set_ch4(true));
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unsafe {
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cortex_m::peripheral::NVIC::unmask(interrupt::PWM_IRQ_WRAP);
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}
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// Tasks require their resources to have 'static lifetime
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// No Mutex needed when sharing within the same executor/prio level
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static AVG: StaticCell<Cell<u32>> = StaticCell::new();
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let avg = AVG.init(Default::default());
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spawner.must_spawn(processing(avg));
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let mut ticker = Ticker::every(Duration::from_secs(1));
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loop {
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ticker.next().await;
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let freq = COUNTER.swap(0, Ordering::Relaxed);
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info!("pwm freq: {:?} Hz", freq);
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info!("adc average: {:?}", avg.get());
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// Update the pwm duty cycle, based on the averaged adc reading
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let mut config = Config::default();
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config.compare_b = ((avg.get() as f32 / 4095.0) * config.top as f32) as _;
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PWM.lock(|p| p.borrow_mut().as_mut().unwrap().set_config(&config));
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}
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}
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#[embassy_executor::task]
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async fn processing(avg: &'static Cell<u32>) {
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let mut buffer: heapless::HistoryBuffer<u16, 100> = Default::default();
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loop {
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let val = ADC_VALUES.receive().await;
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buffer.write(val);
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let sum: u32 = buffer.iter().map(|x| *x as u32).sum();
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avg.set(sum / buffer.len() as u32);
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}
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}
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#[interrupt]
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fn PWM_IRQ_WRAP() {
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critical_section::with(|cs| {
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let mut adc = ADC.borrow(cs).borrow_mut();
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let (adc, p26) = adc.as_mut().unwrap();
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let val = adc.blocking_read(p26).unwrap();
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ADC_VALUES.try_send(val).ok();
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// Clear the interrupt, so we don't immediately re-enter this irq handler
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PWM.borrow(cs).borrow_mut().as_mut().unwrap().clear_wrapped();
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});
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COUNTER.fetch_add(1, Ordering::Relaxed);
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}
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