mirror of
https://github.com/italicsjenga/rp-hal-boards.git
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126 lines
3.3 KiB
Rust
126 lines
3.3 KiB
Rust
//! # Pico PWM Blink Example
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//!
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//! Fades the LED on a Pico board using the PWM peripheral.
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//!
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//! This will fade in/out the LED attached to GP25, which is the pin the Pico
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//! uses for the on-board LED.
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//!
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//! See the `Cargo.toml` file for Copyright and licence details.
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#![no_std]
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#![no_main]
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// The macro for our start-up function
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use cortex_m_rt::entry;
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// GPIO traits
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use embedded_hal::PwmPin;
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// Time handling traits
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use embedded_time::rate::*;
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// Ensure we halt the program on panic (if we don't mention this crate it won't
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// be linked)
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use panic_halt as _;
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// Pull in any important traits
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use pico::hal::prelude::*;
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// A shorter alias for the Peripheral Access Crate, which provides low-level
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// register access
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use pico::hal::pac;
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// A shorter alias for the Hardware Abstraction Layer, which provides
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// higher-level drivers.
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use pico::hal;
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/// The linker will place this boot block at the start of our program image. We
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/// need this to help the ROM bootloader get our code up and running.
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#[link_section = ".boot2"]
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#[used]
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pub static BOOT2: [u8; 256] = rp2040_boot2::BOOT_LOADER;
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// The minimum PWM value (i.e. LED brightness) we want
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const LOW: u16 = 0;
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// The maximum PWM value (i.e. LED brightness) we want
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const HIGH: u16 = 25000;
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/// Entry point to our bare-metal application.
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///
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/// The `#[entry]` macro ensures the Cortex-M start-up code calls this function
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/// as soon as all global variables are initialised.
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///
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/// The function configures the RP2040 peripherals, then fades the LED in an
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/// infinite loop.
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#[entry]
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fn main() -> ! {
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// Grab our singleton objects
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let mut pac = pac::Peripherals::take().unwrap();
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let core = pac::CorePeripherals::take().unwrap();
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// Set up the watchdog driver - needed by the clock setup code
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let mut watchdog = hal::watchdog::Watchdog::new(pac.WATCHDOG);
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// Configure the clocks
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//
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// Our default is 12 MHz crystal input, 125 MHz system clock
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let clocks = hal::clocks::init_clocks_and_plls(
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pico::XOSC_CRYSTAL_FREQ,
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pac.XOSC,
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pac.CLOCKS,
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pac.PLL_SYS,
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pac.PLL_USB,
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&mut pac.RESETS,
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&mut watchdog,
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)
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.ok()
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.unwrap();
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// The single-cycle I/O block controls our GPIO pins
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let sio = hal::sio::Sio::new(pac.SIO);
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// Set the pins up according to their function on this particular board
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let pins = pico::Pins::new(
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pac.IO_BANK0,
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pac.PADS_BANK0,
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sio.gpio_bank0,
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&mut pac.RESETS,
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);
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// The delay object lets us wait for specified amounts of time (in
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// milliseconds)
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let mut delay = cortex_m::delay::Delay::new(core.SYST, clocks.system_clock.freq().integer());
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// Init PWMs
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let mut pwm_slices = hal::pwm::Slices::new(pac.PWM, &mut pac.RESETS);
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// Configure PWM4
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let pwm = &mut pwm_slices.pwm4;
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pwm.set_ph_correct();
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pwm.enable();
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// Output channel B on PWM4 to the LED pin
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let channel = &mut pwm.channel_b;
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channel.output_to(pins.led);
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// Infinite loop, fading LED up and down
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loop {
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// Ramp brightness up
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for i in (LOW..=HIGH).skip(100) {
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delay.delay_us(8);
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channel.set_duty(i);
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}
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// Ramp brightness down
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for i in (LOW..=HIGH).rev().skip(100) {
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delay.delay_us(8);
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channel.set_duty(i);
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}
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delay.delay_ms(500);
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}
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}
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// End of file
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