How to use Embassy Timer in a multicore application?

[yanshay]

I need to use mulththreaded embassy using two cores on ESP32, so I started by trying out the simplest program that loops and logs from two embassy threads. Same as the examle at https://github.com/esp-rs/esp-hal/blob/main/esp32-hal/examples/embassy_multicore.rs except that its simpler, just trying to loop with a Timer.

It doesn't work. The Timer on the 2nd executor doesn't function, it just waits forever.
How can I use a TImer on the other thread?

Edit: Adding to the above, I continued to add wifi to the 2nd executor, and at some point suddenly Timer also started working.
After (another spawned task) I added a call to esp_wifi::initialize, the Timer started working ..?!? Any ideas how that solved it?

Here is the program:

#![no_std]
#![no_main]
#![feature(type_alias_impl_trait)]

use embassy_executor::Spawner;
use embassy_time::{Duration, Ticker};
use hal::{
    clock::ClockControl,
    cpu_control::{CpuControl, Stack},
    embassy::{self, executor::Executor},
    get_core,
    peripherals::Peripherals,
    prelude::*,
    timer::TimerGroup,
};
use esp_backtrace as _;
use esp_println::println;
use static_cell::make_static;

static mut APP_CORE_STACK: Stack<8192> = Stack::new();

/// Waits for a message that contains a duration, then flashes a led for that
/// duration of time.
#[embassy_executor::task]
async fn control_led(
) {
    let mut ticker = Ticker::every(Duration::from_secs(1));
    loop {
        println!("Other Thread on core {:?}", get_core() as usize);
        ticker.next().await; // <----- This awaits indefinitely
    }
}

#[main]
async fn main(_spawner: Spawner) {
    let peripherals = Peripherals::take();
    let system = peripherals.SYSTEM.split();
    let clocks = ClockControl::boot_defaults(system.clock_control).freeze();

    let timer_group0 = TimerGroup::new(peripherals.TIMG0, &clocks);
    embassy::init(&clocks, timer_group0.timer0);

    let mut cpu_control = CpuControl::new(system.cpu_control);

    let cpu1_fnctn = move || {
        let executor = make_static!(Executor::new());
        executor.run(|spawner| {
            spawner.spawn(control_led()).ok();
        });
    };
    let _guard = cpu_control
        .start_app_core(unsafe { &mut APP_CORE_STACK }, cpu1_fnctn)
        .unwrap();

    let mut ticker = Ticker::every(Duration::from_secs(2));
    loop {
        println!("Main thread on core {}", get_core() as usize);
        ticker.next().await;
    }
}

[MabezDev]

Opting into the generic-queue feature of embassy-time should fix this. The TIMG time driver on the esp32 only has two timer slots, the generic queue can do more.

[Fundevoge]

When I add this feature to embassy-time 0.2.0, I get this linker error:

ld.exe: target\xtensa-esp32-none-elf\debug\deps\libembassy_time-4f88757de0054fda.rlib(embassy_time-4f88757de0054fda.embassy_time.eb23ab1cc4240fa4-cgu.0.rcgu.o): in function `_embassy_time_schedule_wake':
          .cargo\git\checkouts\embassy-9312dcb0ed774b29\0027a76\embassy-time/src/queue.rs:56: multiple definition of `_embassy_time_schedule_wake'; target\xtensa-esp32-none-elf\debug\deps\libembassy_executor-ec499154f390f92e.rlib(embassy_executor-ec499154f390f92e.embassy_executor.a982be24085b6b43-cgu.0.rcgu.o):.cargo\git\checkouts\embassy-9312dcb0ed774b29\0027a76\embassy-time\src/queue.rs:56: first defined here

Which points to

macro_rules! timer_queue_impl {
    (static $name:ident: $t: ty = $val:expr) => {
        static $name: $t = $val;

        #[no_mangle]
        fn _embassy_time_schedule_wake(at: $crate::Instant, waker: &core::task::Waker) {
            <$t as $crate::queue::TimerQueue>::schedule_wake(&$name, at, waker);
        }
    };
}

The issue still exists in 0.3.0

ld.exe: target\xtensa-esp32-none-elf\release\deps\libembassy_executor-547ced2fa939af1f.rlib(embassy_executor-547ced2fa939af1f.embassy_executor.9dca34662c3a56c5-cgu.0.rcgu.o): in function `_embassy_time_schedule_wake':
          embassy_executor.9dca34662c3a56c5-cgu.0:(.text._embassy_time_schedule_wake+0x0): multiple definition of `_embassy_time_schedule_wake'; target\xtensa-esp32-none-elf\release\deps\libembassy_time-08cf6ad5e4810af5.rlib(embassy_time-08cf6ad5e4810af5.embassy_time.f5f88c1db7a892c6-cgu.0.rcgu.o):embassy_time.f5f88c1db7a892c6-cgu.0:(.text._embassy_time_schedule_wake+0x0): first defined here

[HazMux]

I also have undefined reference to '_embassy_time_schedule_wake' error with example embassy hello world.rs, until i remove embassy_time

[HazMux]

Added integrated-timers feature to embassy-executor, now it works

[nan-mu]

This does work. I think it's necessary to add this hint to the relevant examples or reconsider the correct way to demonstrate the examples. Additionally, I have spent a lot of time searching for this issue. Thank you.

[henriquebritoM]

A true hero doesn't wear a cape.
Thank You, saved my day