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86 lines
2.4 KiB
86 lines
2.4 KiB
#![no_main] |
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#![no_std] |
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extern crate cortex_m; |
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extern crate cortex_m_rt; |
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extern crate panic_halt; |
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extern crate stm32f0xx_hal as hal; |
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use hal::gpio::*; |
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use hal::prelude::*; |
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use hal::stm32; |
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use cortex_m::interrupt::Mutex; |
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use cortex_m::peripheral::syst::SystClkSource::Core; |
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use cortex_m::peripheral::Peripherals; |
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use cortex_m_rt::{entry, exception}; |
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use core::cell::RefCell; |
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use core::ops::DerefMut; |
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static GPIO: Mutex<RefCell<Option<gpioa::PA1<Output<PushPull>>>>> = Mutex::new(RefCell::new(None)); |
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#[entry] |
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fn main() -> ! { |
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if let (Some(p), Some(cp)) = (stm32::Peripherals::take(), Peripherals::take()) { |
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let gpioa = p.GPIOA.split(); |
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let mut rcc = p.RCC.constrain(); |
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let _ = rcc.cfgr.sysclk(48.mhz()).freeze(); |
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let mut syst = cp.SYST; |
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/* (Re-)configure PA1 as output */ |
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let mut led = gpioa.pa1.into_push_pull_output(); |
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cortex_m::interrupt::free(move |cs| { |
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*GPIO.borrow(cs).borrow_mut() = Some(led); |
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}); |
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/* Initialise SysTick counter with a defined value */ |
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unsafe { syst.cvr.write(1) }; |
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/* Set source for SysTick counter, here full operating frequency (== 8MHz) */ |
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syst.set_clock_source(Core); |
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/* Set reload value, i.e. timer delay 48 MHz/4 Mcounts == 12Hz or 83ms */ |
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syst.set_reload(4_000_000 - 1); |
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/* Start counter */ |
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syst.enable_counter(); |
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/* Start interrupt generation */ |
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syst.enable_interrupt(); |
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} |
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loop { |
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continue; |
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} |
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} |
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/* Define an exception, i.e. function to call when exception occurs. Here if our SysTick timer |
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* trips the flash function will be called and the specified stated passed in via argument */ |
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//, flash, state: u8 = 1); |
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#[exception] |
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fn SysTick() -> ! { |
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static mut state: u8 = 1; |
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/* Enter critical section */ |
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cortex_m::interrupt::free(|cs| { |
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if let Some(ref mut led) = *GPIO.borrow(cs).borrow_mut().deref_mut() { |
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/* Check state variable, keep LED off most of the time and turn it on every 10th tick */ |
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if *state < 10 { |
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/* If set turn off the LED */ |
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led.set_low(); |
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/* And now increment state variable */ |
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*state += 1; |
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} else { |
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/* If not set, turn on the LED */ |
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led.set_high(); |
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/* And set new state variable back to 0 */ |
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*state = 0; |
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} |
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} |
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}); |
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}
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