main-body.rs

fn main() -> ! {
    //  Show "Hello, world!" on the debug console, which is shown in OpenOCD. "mut" means that this object is mutable, i.e. it can change.
    let mut debug_out = hio::hstdout().unwrap();
    writeln!(debug_out, "Hello, world!").unwrap();

    //  Get peripherals (clocks, flash memory, GPIO) for the STM32 Blue Pill microcontroller.
    let bluepill = Peripherals::take().unwrap();

    //  Get the clocks from the STM32 Reset and Clock Control (RCC) and freeze the Flash Access Control Register (ACR).
    let mut rcc = bluepill.RCC.constrain();
    let mut flash = bluepill.FLASH.constrain();
    let clocks = rcc.cfgr.freeze(&mut flash.acr);

    //  Get GPIO Port C, which also enables the Advanced Peripheral Bus 2 (APB2) clock for Port C.
    let mut gpioc = bluepill.GPIOC.split(&mut rcc.apb2);

    //  Use Pin PC 13 of the Blue Pill for GPIO Port C. Select Output Push/Pull mode for the pin, which is connected to our LED.
    let mut led = gpioc.pc13.into_push_pull_output(&mut gpioc.crh);

    //  Create a delay timer from the RCC clocks.
    let cp = cortex_m::Peripherals::take().unwrap();
    let mut delay = Delay::new(cp.SYST, clocks);

    //  Loop forever.
    loop {
        //  Output 3.3V on the LED Pin and show a message in OpenOCD console.
        led.set_high();
        writeln!(debug_out, "LED is ON!").unwrap();

        //  Wait 1,000 millisec (1 sec).
        delay.delay_ms(1_000_u16);

        //  Output 0V on the LED Pin and show a message in OpenOCD console.
        led.set_low();
        writeln!(debug_out, "LED is OFF!").unwrap();

        //  Wait 1,000 millisec (1 sec).
        delay.delay_ms(1_000_u16);
    }
}