Mutating struct in ISR

[willAlbertini707]

I have an ISR that is attached to a timer alarm and called every two seconds. In this ISR there is a flag (AtomicBool) and a struct I want to update. I have the struct contained in a Mutex<RefCell<>>.

use esp_idf_svc::hal;
use hal::peripherals::Peripherals;
use hal::timer::TimerDriver;
use hal::timer::config;

use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::Mutex;
use std::cell::RefCell;

static FLAG: AtomicBool = AtomicBool::new(false);

struct InterruptCount {
count: i32,
}

static COUNTER: Mutex<RefCell> = Mutex::new(RefCell::new(InterruptCount{count:1}));

fn increment_interrupt() {
hal::interrupt::free(|| {
FLAG.store(true, Ordering::Relaxed);
COUNTER.lock().unwrap().borrow_mut().count += 1;
});
}

I can change the flag (runs without COUNTER.lock().unwrap().borrow_mut().count += 1;), but get the following error when trying to increment the struct field "count":

Guru Meditation Error: Core 0 panic'ed (Interrupt wdt timeout on CPU0).

I know I am probably missing something important. The ISR works without trying to modify COUNTER. I am wondering how to safely mutate a struct in an ISR?

[ivmarkov]

You cannot use Rust STD mutexes from. An ISR. Use an esp idf hal CriticalSection I stead, or a Queue or post to an esp idf event loop.