//! Blinks an LED
//!
//! This assumes that a LED is connected to pc13 as is the case on the blue pill board.
//!
//! Note: Without additional hardware, PC13 should not be used to drive an LED, see page 5.1.2 of
//! the reference manaual for an explanation. This is not an issue on the blue pill.

#![deny(unsafe_code)]
#![deny(warnings)]
#![no_std]
#![no_main]

extern crate panic_halt;

use nb::block;

use stm32f1xx_hal::{
    prelude::*,
    pac,
    timer::Timer,
};
use cortex_m_rt::entry;

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

    let mut flash = dp.FLASH.constrain();
    let mut rcc = dp.RCC.constrain();

    // Try a different clock configuration
    let clocks = rcc.cfgr.freeze(&mut flash.acr);
    // let clocks = rcc.cfgr
    //     .sysclk(64.mhz())
    //     .pclk1(32.mhz())
    //     .freeze(&mut flash.acr);

    let mut gpioc = dp.GPIOC.split(&mut rcc.apb2);

    let mut led = gpioc.pc13.into_push_pull_output(&mut gpioc.crh);
    // Try a different timer (even SYST)
    let mut timer = Timer::syst(cp.SYST, 1.hz(), clocks);
    loop {
        block!(timer.wait()).unwrap();
        led.set_high();
        block!(timer.wait()).unwrap();
        led.set_low();
    }
}