Merge pull request #3433 from 1-rafael-1/rp-pwm-embedded-hal-traits

embassy_rp: implement pwm traits from embedded_hal

1 files changed, 52 insertions, 6 deletions

diff --git a/examples/rp/src/bin/pwm.rs b/examples/rp/src/bin/pwm.rs
index 26e233260..791b88b5b 100644
--- a/examples/rp/src/bin/pwm.rs
+++ b/examples/rp/src/bin/pwm.rs
@@ -1,24 +1,36 @@
 //! This example shows how to use PWM (Pulse Width Modulation) in the RP2040 chip.
 //!
-//! The LED on the RP Pico W board is connected differently. Add a LED and resistor to another pin.
+//! We demonstrate two ways of using PWM:
+//! 1. Via config
+//! 2. Via setting a duty cycle
 
 #![no_std]
 #![no_main]
 
 use defmt::*;
 use embassy_executor::Spawner;
-use embassy_rp::pwm::{Config, Pwm};
+use embassy_rp::peripherals::{PIN_25, PIN_4, PWM_SLICE2, PWM_SLICE4};
+use embassy_rp::pwm::{Config, Pwm, SetDutyCycle};
 use embassy_time::Timer;
 use {defmt_rtt as _, panic_probe as _};
 
 #[embassy_executor::main]
-async fn main(_spawner: Spawner) {
+async fn main(spawner: Spawner) {
     let p = embassy_rp::init(Default::default());
+    spawner.spawn(pwm_set_config(p.PWM_SLICE4, p.PIN_25)).unwrap();
+    spawner.spawn(pwm_set_dutycycle(p.PWM_SLICE2, p.PIN_4)).unwrap();
+}
 
-    let mut c: Config = Default::default();
-    c.top = 0x8000;
+/// Demonstrate PWM by modifying & applying the config
+///
+/// Using the onboard led, if You are using a different Board than plain Pico2 (i.e. W variant)
+/// you must use another slice & pin and an appropriate resistor.
+#[embassy_executor::task]
+async fn pwm_set_config(slice4: PWM_SLICE4, pin25: PIN_25) {
+    let mut c = Config::default();
+    c.top = 32_768;
     c.compare_b = 8;
-    let mut pwm = Pwm::new_output_b(p.PWM_SLICE4, p.PIN_25, c.clone());
+    let mut pwm = Pwm::new_output_b(slice4, pin25, c.clone());
 
     loop {
         info!("current LED duty cycle: {}/32768", c.compare_b);
@@ -27,3 +39,37 @@ async fn main(_spawner: Spawner) {
         pwm.set_config(&c);
     }
 }
+
+/// Demonstrate PWM by setting duty cycle
+///
+/// Using GP4 in Slice2, make sure to use an appropriate resistor.
+#[embassy_executor::task]
+async fn pwm_set_dutycycle(slice2: PWM_SLICE2, pin4: PIN_4) {
+    // If we aim for a specific frequency, here is how we can calculate the top value.
+    // The top value sets the period of the PWM cycle, so a counter goes from 0 to top and then wraps around to 0.
+    // Every such wraparound is one PWM cycle. So here is how we get 25KHz:
+    let mut c = Config::default();
+    let pwm_freq = 25_000; // Hz, our desired frequency
+    let clock_freq = embassy_rp::clocks::clk_sys_freq();
+    c.top = (clock_freq / pwm_freq) as u16 - 1;
+
+    let mut pwm = Pwm::new_output_a(slice2, pin4, c.clone());
+
+    loop {
+        // 100% duty cycle, fully on
+        pwm.set_duty_cycle_fully_on().unwrap();
+        Timer::after_secs(1).await;
+
+        // 66% duty cycle. Expressed as simple percentage.
+        pwm.set_duty_cycle_percent(66).unwrap();
+        Timer::after_secs(1).await;
+
+        // 25% duty cycle. Expressed as 32768/4 = 8192.
+        pwm.set_duty_cycle(c.top / 4).unwrap();
+        Timer::after_secs(1).await;
+
+        // 0% duty cycle, fully off.
+        pwm.set_duty_cycle_fully_off().unwrap();
+        Timer::after_secs(1).await;
+    }
+}