nrf52840 timer attempt

not_working.rs

#![no_main]
#![no_std]

use core::cell::RefCell;

use cortex_m::{interrupt::Mutex, peripheral::NVIC, prelude::_embedded_hal_timer_CountDown};
use cortex_m_rt::entry;
use hal::{
	pac::{interrupt, Interrupt, Peripherals, TIMER0},
	timer::Periodic,
	Timer,
};
use nrf52840_hal as hal;

static TIMER: Mutex<RefCell<Option<Timer<TIMER0, Periodic>>>> = Mutex::new(RefCell::new(None));

#[entry]
fn main() -> ! {
	let periph = Peripherals::take().unwrap();

	unsafe {
		NVIC::unmask(Interrupt::TIMER0);
	}

	let mut timer = Timer::periodic(periph.TIMER0);
	timer.enable_interrupt();
	timer.start(2_000_000u32);

	cortex_m::interrupt::free(move |cs| {
		*TIMER.borrow(cs).borrow_mut() = Some(timer);
	});

	loop {}
}

#[interrupt]
fn TIMER0() {
	cortex_m::interrupt::free(move |cs| {
		let mut timer_cell = TIMER.borrow(cs).borrow_mut();
		let timer = timer_cell.as_mut().unwrap();
		timer.event_compare_cc0().reset();
	})
}

#[panic_handler]
fn panic(_: &core::panic::PanicInfo) -> ! {
	loop {
		cortex_m::asm::bkpt();
	}
}