ledc: add support for fading leds (#519)

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 - `Send` for `AsyncCanDriver`
+- `fade_with_time`, `fade_with_step` for `LedcDriver`
 
 ### Fixed
 - Fix the SDMMC driver for ESP-IDF V5.5+

examples/ledc_fade.rs

@@ -0,0 +1,39 @@
+use esp_idf_hal::delay::FreeRtos;
+use esp_idf_hal::ledc::{config::TimerConfig, LedcDriver, LedcTimerDriver};
+use esp_idf_hal::peripherals::Peripherals;
+use esp_idf_hal::prelude::*;
+use std::time::Duration;
+
+fn main() -> anyhow::Result<()> {
+    esp_idf_hal::sys::link_patches();
+
+    let peripherals = Peripherals::take()?;
+
+    let timer_driver = LedcTimerDriver::new(
+        peripherals.ledc.timer0,
+        &TimerConfig::default().frequency(25.kHz().into()),
+    )?;
+
+    let mut ledc_driver = LedcDriver::new(
+        peripherals.ledc.channel0,
+        timer_driver,
+        peripherals.pins.gpio7,
+    )?;
+
+    for _ in 0..2 {
+        // Fade up over 2 seconds
+        ledc_driver.fade_with_time(
+            ledc_driver.get_max_duty(),
+            Duration::from_secs(2).as_millis() as i32,
+            true,
+        )?;
+
+        // Fade down over 2 seconds
+        ledc_driver.fade_with_time(0, Duration::from_secs(2).as_millis() as i32, true)?;
+    }
+
+    ledc_driver.set_duty(ledc_driver.get_max_duty() / 10)?;
+    FreeRtos::delay_ms(10000);
+
+    Ok(())
+}

src/ledc.rs

@@ -3,8 +3,6 @@
 //! Interface to the [LED Control (LEDC)
 //! peripheral](https://docs.espressif.com/projects/esp-idf/en/latest/esp32c3/api-reference/peripherals/ledc.html)
 //!
-//! This is an initial implementation supporting the generation of PWM signals
-//! but no chrome and spoilers like fading.
 //!
 //! # Examples
 //!
@@ -323,6 +321,69 @@ impl<'d> LedcDriver<'d> {
     pub fn timer(&self) -> ledc_timer_t {
         self.timer as _
     }
+
+    /// Fade the LED to a target duty cycle over a specified time
+    pub fn fade_with_time(
+        &mut self,
+        target_duty: u32,
+        fade_time_ms: i32,
+        wait: bool,
+    ) -> Result<(), EspError> {
+        let max_duty = self.get_max_duty();
+        if target_duty > max_duty {
+            return Err(EspError::from_infallible::<ESP_ERR_INVALID_ARG>());
+        }
+
+        let fade_mode = if wait {
+            ledc_fade_mode_t_LEDC_FADE_WAIT_DONE
+        } else {
+            ledc_fade_mode_t_LEDC_FADE_NO_WAIT
+        };
+
+        unsafe {
+            esp!(ledc_set_fade_with_time(
+                self.speed_mode,
+                self.channel(),
+                target_duty,
+                fade_time_ms
+            ))?;
+            esp!(ledc_fade_start(self.speed_mode, self.channel(), fade_mode))?;
+        }
+        Ok(())
+    }
+
+    /// Fade the LED to a target duty cycle using steps
+    pub fn fade_with_step(
+        &mut self,
+        target_duty: u32,
+        step_size: u32,
+        step_time_ms: u32,
+        wait: bool,
+    ) -> Result<(), EspError> {
+        let max_duty = self.get_max_duty();
+        if target_duty > max_duty {
+            return Err(EspError::from_infallible::<ESP_ERR_INVALID_ARG>());
+        }
+
+        let fade_mode = if wait {
+            ledc_fade_mode_t_LEDC_FADE_WAIT_DONE
+        } else {
+            ledc_fade_mode_t_LEDC_FADE_NO_WAIT
+        };
+
+        unsafe {
+            esp!(ledc_set_fade_with_step(
+                self.speed_mode,
+                self.channel(),
+                target_duty,
+                step_size,
+                step_time_ms,
+            ))?;
+
+            esp!(ledc_fade_start(self.speed_mode, self.channel(), fade_mode))?;
+        }
+        Ok(())
+    }
 }
 
 impl Drop for LedcDriver<'_> {