//! 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 manual for an explanation. This is not an issue on the blue pill.

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

//use panic_halt as _;
use core::panic::PanicInfo;
use rtt_target::{rprintln, rtt_init_print};

use nb::block;

use stm32f1xx_hal::{
    prelude::*,
    pac,
    timer::Timer,
};
use cortex_m_rt::entry;
use embedded_hal::digital::v2::OutputPin;

#[entry]
fn main() -> ! {
    // Init buffers for debug printing
    rtt_init_print!();
    // Get access to the core peripherals from the cortex-m crate
    let cp = cortex_m::Peripherals::take().unwrap();
    // Get access to the device specific peripherals from the peripheral access crate
    let dp = pac::Peripherals::take().unwrap();

    // Take ownership over the raw flash and rcc devices and convert them into the corresponding
    // HAL structs
    let mut flash = dp.FLASH.constrain();
    let mut rcc = dp.RCC.constrain();

    // Freeze the configuration of all the clocks in the system and store the frozen frequencies in
    // `clocks`
    let clocks = rcc.cfgr.freeze(&mut flash.acr);

    // Acquire the GPIOC peripheral
    let mut gpioc = dp.GPIOC.split(&mut rcc.apb2);

    // Configure gpio C pin 13 as a push-pull output. The `crh` register is passed to the function
    // in order to configure the port. For pins 0-7, crl should be passed instead.
    let mut led = gpioc.pc13.into_push_pull_output(&mut gpioc.crh);
    // Configure the syst timer to trigger an update every second
    let mut timer = Timer::syst(cp.SYST, &clocks).start_count_down(1.hz());

    rprintln!("Hello, Rust!");
    // Wait for the timer to trigger an update and change the state of the LED
    let mut i = 0;
    loop {
        block!(timer.wait()).unwrap();
        led.set_high().unwrap();
        block!(timer.wait()).unwrap();
        led.set_low().unwrap();
        i += 1;
        rprintln!("Hello again; I have blinked {} times.", i);
        if i == 10 {
            panic!("Yow, 10 times is enough!");
        }
    }
}

#[inline(never)]
#[panic_handler]
fn panic(info: &PanicInfo) -> ! {
    rprintln!("{}", info);
    loop {} // You might need a compiler fence in here.
}