gistfile1.txt

// std and main are not available for bare metal software
#![no_std]
#![no_main]

//extern crate panic_halt;
extern crate panic_semihosting;
extern crate stm32f1xx_hal;

extern crate cortex_m_semihosting;

use nb::block;

use cortex_m_semihosting::hprintln;

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


// use `main` as the entry point of this application
#[entry]
fn main() -> ! {
    // 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 GPIOA peripheral
    let mut gpioa = dp.GPIOA.split(&mut rcc.apb2);

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

    // Prepare the alternate function I/O registers
    let mut afio = dp.AFIO.constrain(&mut rcc.apb2);

    // USART1
    let tx = gpioa.pa9.into_alternate_push_pull(&mut gpioa.crh);
    let rx = gpioa.pa10;

    // Set up the usart device. Taks ownership over the USART register and tx/rx pins. The rest of
    // the registers are used to enable and configure the device.
    let serial = Serial::usart1(
        dp.USART1,
        (tx, rx),
        &mut afio.mapr,
        9_600.bps(),
        clocks,
        &mut rcc.apb2,
    );

    hprintln!("Hello, world!").unwrap();

    // Pins PA9 and PA10 have been routed to e.g. an UART <-> USB adapter so they
    // can only be used for serial communication
    // `Serial1` represents that serial interface
    //pub type Serial1 = Serial<USART1, PA9<AF7>, PA10<AF7>>;

    // Configure gpio C pin 6 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 led1 = gpioc.pc6.into_push_pull_output(&mut gpioc.crl);
    let mut led2 = gpioc.pc7.into_push_pull_output(&mut gpioc.crl);
    // Configure the syst timer to trigger an update every second
    let mut timer = Timer::syst(cp.SYST, 1.hz(), clocks);

    // Split the serial struct into a receiving and a transmitting part
    let (mut tx, mut rx) = serial.split();

    // Wait for the timer to trigger an update and change the state of the LED
    loop {
        block!(timer.wait()).unwrap();
        led1.set_low();
        led2.set_high();
        let sent = b'X';
        block!(tx.write(sent)).ok();
        block!(timer.wait()).unwrap();
        led1.set_high();
        led2.set_low();
        let sent = b'Y';
        block!(tx.write(sent)).ok();
    }
}