Add docs to RP2040 PWM

embassy-rp/src/pwm.rs

@@ -10,16 +10,40 @@ use crate::gpio::sealed::Pin as _;
 use crate::gpio::{AnyPin, Pin as GpioPin};
 use crate::{pac, peripherals, RegExt};
 
+/// The configuration of a PWM slice.
+///Note the period in clock cycles of a slice can be computed as:
+/// (top + 1) * (phase_correct ? 1 : 2) * divider
 #[non_exhaustive]
 #[derive(Clone)]
 pub struct Config {
+    /// Inverts the PWM output signal on channel A.
     pub invert_a: bool,
+    /// Inverts the PWM output signal on channel B.
     pub invert_b: bool,
+    /// Enables phase-correct mode for PWM operation.
+    /// In phase-correct mode, the PWM signal is generated in such a way that
+    /// the pulse is always centered regardless of the duty cycle.
+    /// The output frequency is halved when phase-correct mode is enabled.
     pub phase_correct: bool,
+    /// Enables the PWM slice, allowing it to generate an output.
+    /// When disabled, the PWM slice will not produce any output.
     pub enable: bool,
+    /// A fractional clock divider, represented as a fixed-point number with
+    /// 8 integer bits and 4 fractional bits. It allows precise control over
+    /// the PWM output frequency by gating the PWM counter increment.
+    /// A higher value will result in a slower output frequency.
     pub divider: fixed::FixedU16<fixed::types::extra::U4>,
+    /// The output on channel A goes high when `compare_a` is higher than the
+    /// counter. A compare of 0 will produce an always low output, while a 
+    /// compare of `top` + 1 will produce an always high output.
     pub compare_a: u16,
+    /// The output on channel B goes high when `compare_b` is higher than the
+    /// counter. A compare of 0 will produce an always low output, while a 
+    /// compare of `top` + 1 will produce an always high output.
     pub compare_b: u16,
+    /// The point at which the counter wraps, representing the maximum possible
+    /// period. The counter will either wrap to 0 or reverse depending on the 
+    /// setting of `phase_correct`.
     pub top: u16,
 }
 
@@ -173,6 +197,9 @@ impl<'d, T: Channel> Pwm<'d, T> {
         });
     }
 
+    /// Advances a slice’s output phase by one count while it is running 
+    /// by inserting or deleting pulses from the clock enable. The counter 
+    /// will not count faster than once per cycle.
     #[inline]
     pub fn phase_advance(&mut self) {
         let p = self.inner.regs();
@@ -180,6 +207,9 @@ impl<'d, T: Channel> Pwm<'d, T> {
         while p.csr().read().ph_adv() {}
     }
 
+    /// Retards a slice’s output phase by one count while it is running 
+    /// by deleting pulses from the clock enable. The counter will not
+    /// count backward when clock enable is permenantly low
     #[inline]
     pub fn phase_retard(&mut self) {
         let p = self.inner.regs();