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76 lines
2.6 KiB
Rust
76 lines
2.6 KiB
Rust
//! This example shows how to use PWM (Pulse Width Modulation) in the RP2040 chip.
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//!
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//! We demonstrate two ways of using PWM:
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//! 1. Via config
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//! 2. Via setting a duty cycle
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#![no_std]
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#![no_main]
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use defmt::*;
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use embassy_executor::Spawner;
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use embassy_rp::peripherals::{PIN_25, PIN_4, PWM_SLICE2, PWM_SLICE4};
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use embassy_rp::pwm::{Config, Pwm, SetDutyCycle};
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use embassy_time::Timer;
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use {defmt_rtt as _, panic_probe as _};
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#[embassy_executor::main]
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async fn main(spawner: Spawner) {
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let p = embassy_rp::init(Default::default());
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spawner.spawn(pwm_set_config(p.PWM_SLICE4, p.PIN_25)).unwrap();
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spawner.spawn(pwm_set_dutycycle(p.PWM_SLICE2, p.PIN_4)).unwrap();
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}
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/// Demonstrate PWM by modifying & applying the config
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///
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/// Using the onboard led, if You are using a different Board than plain Pico2 (i.e. W variant)
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/// you must use another slice & pin and an appropriate resistor.
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#[embassy_executor::task]
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async fn pwm_set_config(slice4: PWM_SLICE4, pin25: PIN_25) {
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let mut c = Config::default();
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c.top = 32_768;
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c.compare_b = 8;
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let mut pwm = Pwm::new_output_b(slice4, pin25, c.clone());
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loop {
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info!("current LED duty cycle: {}/32768", c.compare_b);
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Timer::after_secs(1).await;
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c.compare_b = c.compare_b.rotate_left(4);
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pwm.set_config(&c);
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}
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}
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/// Demonstrate PWM by setting duty cycle
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///
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/// Using GP4 in Slice2, make sure to use an appropriate resistor.
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#[embassy_executor::task]
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async fn pwm_set_dutycycle(slice2: PWM_SLICE2, pin4: PIN_4) {
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// If we aim for a specific frequency, here is how we can calculate the top value.
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// The top value sets the period of the PWM cycle, so a counter goes from 0 to top and then wraps around to 0.
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// Every such wraparound is one PWM cycle. So here is how we get 25KHz:
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let mut c = Config::default();
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let pwm_freq = 25_000; // Hz, our desired frequency
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let clock_freq = embassy_rp::clocks::clk_sys_freq();
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c.top = (clock_freq / pwm_freq) as u16 - 1;
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let mut pwm = Pwm::new_output_a(slice2, pin4, c.clone());
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loop {
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// 100% duty cycle, fully on
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pwm.set_duty_cycle_fully_on().unwrap();
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Timer::after_secs(1).await;
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// 66% duty cycle. Expressed as simple percentage.
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pwm.set_duty_cycle_percent(66).unwrap();
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Timer::after_secs(1).await;
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// 25% duty cycle. Expressed as 32768/4 = 8192.
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pwm.set_duty_cycle(c.top / 4).unwrap();
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Timer::after_secs(1).await;
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// 0% duty cycle, fully off.
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pwm.set_duty_cycle_fully_off().unwrap();
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Timer::after_secs(1).await;
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}
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}
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