LEDC - Allow custom channel selection (espressif#9031)

* feat(ledc): Allow custom channel selection

* fix(ledc): Fix check of maximum channel

* docs(ledc): Add ledcAttachChannel to docs

* feat(ledc): Change channel to uint8_t + add log message

Author: P-R-O-C-H-Y

cores/esp32/esp32-hal-ledc.c

@@ -56,12 +56,11 @@ static bool ledcDetachBus(void * bus){
     return true;
 }
 
-bool ledcAttach(uint8_t pin, uint32_t freq, uint8_t resolution)
+bool ledcAttachChannel(uint8_t pin, uint32_t freq, uint8_t resolution, uint8_t channel)
 {
-    int free_channel = ~ledc_handle.used_channels & (ledc_handle.used_channels+1);
-    if (free_channel == 0 || resolution > LEDC_MAX_BIT_WIDTH)
+    if (channel >= LEDC_CHANNELS || resolution > LEDC_MAX_BIT_WIDTH)
     {
-        log_e("No more LEDC channels available! (maximum %u) or bit width too big (maximum %u)", LEDC_CHANNELS, LEDC_MAX_BIT_WIDTH);
+        log_e("Channel %u is not available! (maximum %u) or bit width too big (maximum %u)", channel, LEDC_CHANNELS, LEDC_MAX_BIT_WIDTH);
         return false;
     }
 
@@ -71,7 +70,6 @@ bool ledcAttach(uint8_t pin, uint32_t freq, uint8_t resolution)
         return false;
     }
 
-    int channel = log2(free_channel & -free_channel);
     uint8_t group=(channel/8), timer=((channel/2)%4);
 
     ledc_timer_config_t ledc_timer = {
@@ -115,8 +113,22 @@ bool ledcAttach(uint8_t pin, uint32_t freq, uint8_t resolution)
         return false;
     }
 
+    log_i("LEDC attached to pin %u (channel %u, resolution %u)", pin, channel, resolution);
     return true;
 }
+
+bool ledcAttach(uint8_t pin, uint32_t freq, uint8_t resolution)
+{
+    uint8_t free_channel = ~ledc_handle.used_channels & (ledc_handle.used_channels+1);
+    if (free_channel == 0 || resolution > LEDC_MAX_BIT_WIDTH){
+        log_e("No more LEDC channels available! (maximum %u) or bit width too big (maximum %u)", LEDC_CHANNELS, LEDC_MAX_BIT_WIDTH);
+        return false;
+    }
+    int channel = log2(free_channel & -free_channel);
+
+    return ledcAttachChannel(pin, freq, resolution, channel);
+}
+
 bool ledcWrite(uint8_t pin, uint32_t duty)
 {
     ledc_channel_handle_t *bus = (ledc_channel_handle_t*)perimanGetPinBus(pin, ESP32_BUS_TYPE_LEDC);

cores/esp32/esp32-hal-ledc.h

@@ -45,6 +45,7 @@ typedef struct {
 
 //channel 0-15 resolution 1-16bits freq limits depend on resolution
 bool        ledcAttach(uint8_t pin, uint32_t freq, uint8_t resolution);
+bool        ledcAttachChannel(uint8_t pin, uint32_t freq, uint8_t resolution, uint8_t channel);
 bool        ledcWrite(uint8_t pin, uint32_t duty);
 uint32_t    ledcWriteTone(uint8_t pin, uint32_t freq);
 uint32_t    ledcWriteNote(uint8_t pin, note_t note, uint8_t octave);

docs/source/api/ledc.rst

@@ -27,6 +27,7 @@ ledcAttach
 **********
 
 This function is used to setup LEDC pin with given frequency and resolution.
+LEDC channel will be selected automatically.
 
 .. code-block:: arduino
 
@@ -41,6 +42,25 @@ This function is used to setup LEDC pin with given frequency and resolution.
 This function will return ``true`` if configuration is successful.
 If ``false`` is returned, error occurs and LEDC channel was not configured.
 
+ledcAttachChannel
+*****************
+
+This function is used to setup LEDC pin with given frequency, resolution and channel.
+
+.. code-block:: arduino
+
+    bool ledcAttachChannel(uint8_t pin, uint32_t freq, uint8_t resolution, uint8_t channel);
+
+* ``pin`` select LEDC pin.
+* ``freq`` select frequency of pwm.
+* ``resolution`` select resolution for LEDC channel. 
+* ``channel`` select LEDC channel.
+ 
+  * range is 1-14 bits (1-20 bits for ESP32).
+  
+This function will return ``true`` if configuration is successful.
+If ``false`` is returned, error occurs and LEDC channel was not configured.
+
 ledcWrite
 *********