stm32l0xx-hal 0.3.0

//! Real-time clock (RTC) example with low APB1 clock frequency


#![no_main]
#![no_std]


extern crate panic_semihosting;


use cortex_m::asm;
use cortex_m_rt::entry;
use stm32l0xx_hal::{
    prelude::*,
    pac,
    pwr::PWR,
    rcc,
    rtc::{
        Instant,
        RTC,
    },
};


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

    // This should put the APB1 clock at 2 times the RTC clock, if I follow the
    // code correctly. Exactly the range that is still acceptable, but requires
    // special handling in the RTC code.
    let mut rcc   = dp.RCC.freeze(rcc::Config::msi(rcc::MSIRange::Range0));
    let mut pwr   = PWR::new(dp.PWR, &mut rcc);
    let     gpiob = dp.GPIOB.split(&mut rcc);

    let mut led = gpiob.pb5.into_push_pull_output();

    let instant = Instant::new()
        .set_year(19)
        .set_month(8)
        .set_day(9)
        .set_hour(13)
        .set_minute(36)
        .set_second(0);

    let mut rtc = RTC::new(
        dp.RTC,
        &mut rcc,
        &mut pwr,
        instant,
    );

    let mut last_second = 0;

    loop {
        let instant = rtc.now();

        if instant.second() != last_second {
            last_second = instant.second();

            // Given the clock settings above, this gives a good blinking going
            // if compiled in release mode.
            led.set_high().unwrap();
            for _ in 0 .. 100 { asm::nop() }
            led.set_low().unwrap();
        }
    }
}