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//! # Pico Blinky Example
//!
//! Blinks the LED on a Pico board.
//!
//! 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 license details.
#![no_std]
#![no_main]
// The macro for our start-up function
use rp_pico::entry;
// GPIO traits
use embedded_hal::digital::OutputPin;
// Ensure we halt the program on panic (if we don't mention this crate it won't
// be linked)
use panic_halt as _;
// Pull in any important traits
use rp_pico::hal::prelude::*;
// A shorter alias for the Peripheral Access Crate, which provides low-level
// register access
use rp_pico::hal::pac;
// A shorter alias for the Hardware Abstraction Layer, which provides
// higher-level drivers.
use rp_pico::hal;
fn is_prime (a : u64) -> bool {
if a % 2 == 0 {return false};
for i in (3..a.isqrt()).step_by(2) {
if a % i == 0 {
return false;
}
}
return true;
}
fn find_next_smaller_prime(mut x : u64) -> u64 {
if x <= 1 {return x};
if x % 2 == 0 {x=x-1};
while !is_prime(x) {x = x - 2};
return x;
}
/// Entry point to our bare-metal application.
///
/// The `#[entry]` macro ensures the Cortex-M start-up code calls this function
/// as soon as all global variables are initialised.
///
/// The function configures the RP2040 peripherals, then blinks the LED in an
/// infinite loop.
#[entry]
fn main() -> ! {
// Grab our singleton objects
let mut pac = pac::Peripherals::take().unwrap();
let core = pac::CorePeripherals::take().unwrap();
// Set up the watchdog driver - needed by the clock setup code
let mut watchdog = hal::Watchdog::new(pac.WATCHDOG);
// Configure the clocks
//
// The default is to generate a 125 MHz system clock
let clocks = hal::clocks::init_clocks_and_plls(
rp_pico::XOSC_CRYSTAL_FREQ,
pac.XOSC,
pac.CLOCKS,
pac.PLL_SYS,
pac.PLL_USB,
&mut pac.RESETS,
&mut watchdog,
)
.ok()
.unwrap();
// The delay object lets us wait for specified amounts of time (in
// milliseconds)
let mut delay = cortex_m::delay::Delay::new(core.SYST, clocks.system_clock.freq().to_Hz());
// The single-cycle I/O block controls our GPIO pins
let sio = hal::Sio::new(pac.SIO);
// Set the pins up according to their function on this particular board
let pins = rp_pico::Pins::new(
pac.IO_BANK0,
pac.PADS_BANK0,
sio.gpio_bank0,
&mut pac.RESETS,
);
// Set the LED to be an output
let mut led_pin = pins.led.into_push_pull_output();
// Blink the LED at 1 Hz
loop {
led_pin.set_high().unwrap();
delay.delay_ms(500);
if find_next_smaller_prime(1<<36) > 5 {
led_pin.set_high().unwrap();
}
led_pin.set_low().unwrap();
delay.delay_ms(500);
}
}
// End of file
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