rp-hal-boards/boards/pico/examples/pico_countdown_blinky.rs

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//! # Pico Countdown Blinky Example
//!
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//! Blinks the LED on a Pico board, using an RP2040 Timer in Count-down mode.
//!
//! This will blink an LED attached to GP25, which is the pin the Pico uses for
//! the on-board LED.
//!
//! See the `Cargo.toml` file for Copyright and licence details.
#![no_std]
#![no_main]
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// The macro for our start-up function
use cortex_m_rt::entry;
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use cortex_m::prelude::*;
// GPIO traits
use embedded_hal::digital::v2::OutputPin;
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// Traits for converting integers to amounts of time
use embedded_time::duration::Extensions;
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// Ensure we halt the program on panic (if we don't mention this crate it won't
// be linked)
use panic_halt as _;
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// A shorter alias for the Peripheral Access Crate, which provides low-level
// register access
use pico::hal::pac;
// A shorter alias for the Hardware Abstraction Layer, which provides
// higher-level drivers.
use pico::hal;
#[entry]
fn main() -> ! {
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// Grab our singleton objects
let mut pac = pac::Peripherals::take().unwrap();
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// Set up the watchdog driver - needed by the clock setup code
let mut watchdog = hal::watchdog::Watchdog::new(pac.WATCHDOG);
// Configure the clocks
//
// The default is to generate a 125 MHz system clock
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let _clocks = hal::clocks::init_clocks_and_plls(
pico::XOSC_CRYSTAL_FREQ,
pac.XOSC,
pac.CLOCKS,
pac.PLL_SYS,
pac.PLL_USB,
&mut pac.RESETS,
&mut watchdog,
)
.ok()
.unwrap();
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// Configure the Timer peripheral in count-down mode
let timer = hal::timer::Timer::new(pac.TIMER, &mut pac.RESETS);
let mut count_down = timer.count_down();
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// The single-cycle I/O block controls our GPIO pins
let sio = hal::sio::Sio::new(pac.SIO);
// Set the pins up according to their function on this particular board
let pins = pico::Pins::new(
pac.IO_BANK0,
pac.PADS_BANK0,
sio.gpio_bank0,
&mut pac.RESETS,
);
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let mut led_pin = pins.led.into_push_pull_output();
// Blink the LED at 1 Hz
loop {
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// LED on, and wait for 500ms
led_pin.set_high().unwrap();
count_down.start(500.milliseconds());
let _ = nb::block!(count_down.wait());
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// LED off, and wait for 500ms
led_pin.set_low().unwrap();
count_down.start(500.milliseconds());
let _ = nb::block!(count_down.wait());
}
}