feat(ledc): Add example and fixes

cores/esp32/esp32-hal-ledc.c

@@ -65,10 +65,10 @@ static bool ledcDetachBus(void *bus) {
     }
   }
   pinMatrixOutDetach(handle->pin, false, false);
-  free(handle);
   if (!channel_found) {
     ledc_handle.used_channels &= ~(1UL << handle->channel);
   }
+  free(handle);
   if (ledc_handle.used_channels == 0) {
     ledc_fade_func_uninstall();
     fade_initialized = false;
@@ -136,8 +136,8 @@ bool ledcAttachChannel(uint8_t pin, uint32_t freq, uint8_t resolution, uint8_t c
   //get resolution of selected channel when used
   if (channel_used) {
     uint32_t channel_resolution = 0;
-    log_i("Channel %u frequency: %u, resolution: %u", channel, ledc_get_freq(group, timer), channel_resolution);
     ledc_ll_get_duty_resolution(LEDC_LL_GET_HW(), group, timer, &channel_resolution);
+    log_i("Channel %u frequency: %u, resolution: %u", channel, ledc_get_freq(group, timer), channel_resolution);
     handle->channel_resolution = (uint8_t)channel_resolution;
   }
   else {

libraries/ESP32/examples/AnalogOut/LEDCSingleChannel/LEDCSingleChannel.ino

@@ -0,0 +1,50 @@
+/*
+ LEDC Software Fade on shared channel with multiple pins
+
+ This example shows how to software fade LED
+ using the ledcWriteChannel function on multiple pins.
+ This example is useful if you need to control synchronously 
+ multiple LEDs on different pins.
+
+ Code adapted from original Arduino Fade example:
+ https://www.arduino.cc/en/Tutorial/Fade
+
+ This example code is in the public domain.
+ */
+
+// use 8 bit precision for LEDC timer
+#define LEDC_TIMER_8_BIT 8
+
+// use 5000 Hz as a LEDC base frequency
+#define LEDC_BASE_FREQ 5000
+
+// LED pins
+#define LED_PIN_1 4
+#define LED_PIN_2 5
+
+// LED channel that will be used instead of automatic selection.
+#define LEDC_CHANNEL 0
+
+int brightness = 0;  // how bright the LED is
+int fadeAmount = 5;  // how many points to fade the LED by
+
+void setup() {
+  // Use single LEDC channel 0 for both pins
+  ledcAttachChannel(LED_PIN_1, LEDC_BASE_FREQ, LEDC_TIMER_8_BIT, LEDC_CHANNEL);
+  ledcAttachChannel(LED_PIN_2, LEDC_BASE_FREQ, LEDC_TIMER_8_BIT, LEDC_CHANNEL);
+}
+
+void loop() {
+  // set the brightness on LEDC channel 0
+  ledcWriteChannel(LEDC_CHANNEL, brightness);
+
+  // change the brightness for next time through the loop:
+  brightness = brightness + fadeAmount;
+
+  // reverse the direction of the fading at the ends of the fade:
+  if (brightness <= 0 || brightness >= 255) {
+    fadeAmount = -fadeAmount;
+  }
+  // wait for 30 milliseconds to see the dimming effect
+  delay(30);
+}