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- //! 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)]
- #![no_std]
- #![no_main]
- use panic_halt as _;
- use nb::block;
- use stm32f1xx_hal::{
- prelude::*,
- pac,
- timer::Timer,
- };
- use cortex_m_rt::entry;
- use embedded_hal::digital::v2::OutputPin;
- #[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 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());
- // Wait for the timer to trigger an update and change the state of the LED
- loop {
- block!(timer.wait()).unwrap();
- led.set_high().unwrap();
- block!(timer.wait()).unwrap();
- led.set_low().unwrap();
- }
- }
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