//! Using a device crate
//!
//! Crates generated using [`svd2rust`] are referred to as device crates. These crates provide an
//! API to access the peripherals of a device.
//!
//! [`svd2rust`]: https://crates.io/crates/svd2rust
//!
//! This example depends on the [`stm32f3`] crate so you'll have to
//! uncomment it in your Cargo.toml.
//!
//! [`stm32f3`]: https://crates.io/crates/stm32f3
//!
//! ```
//! $ edit Cargo.toml && tail $_
//! [dependencies.stm32f3]
//! features = ["stm32f303", "rt"]
//! version = "0.7.1"
//! ```
//!
//! You also need to set the build target to thumbv7em-none-eabihf,
//! typically by editing `.cargo/config` and uncommenting the relevant target line.
//!
//! ---

#![no_main]
#![no_std]

#[allow(unused_extern_crates)]
extern crate panic_halt;

use cortex_m::peripheral::syst::SystClkSource;
use cortex_m_rt::entry;
use cortex_m_semihosting::hprint;
use stm32f3::stm32f303::{interrupt, Interrupt, NVIC};

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

    let mut syst = p.SYST;
    let mut nvic = p.NVIC;

    nvic.enable(Interrupt::EXTI0);

    // configure the system timer to wrap around every second
    syst.set_clock_source(SystClkSource::Core);
    syst.set_reload(8_000_000); // 1s
    syst.enable_counter();

    loop {
        // busy wait until the timer wraps around
        while !syst.has_wrapped() {}

        // trigger the `EXTI0` interrupt
        NVIC::pend(Interrupt::EXTI0);
    }
}

#[interrupt]
fn EXTI0() {
    hprint!(".").unwrap();
}