Add docs for extended microphone config (#2899)

components/microphone/i2s_audio.rst

@@ -13,15 +13,72 @@ The ``i2s_audio`` microphone platform allows you to receive audio via the the
     # Example configuration entry
     microphone:
       - platform: i2s_audio
+        id: external_mic
+        adc_type: external
         i2s_din_pin: GPIO23
 
+      - platform: i2s_audio
+        id: adc_mic
+        adc_type: internal
+        adc_pin: GPIO35
+
+
 Configuration variables:
 ------------------------
 
-- **i2s_din_pin** (**Required**, :ref:`Pin Schema <config-pin_schema>`): The GPIO pin to use for the I²S DIN (Data In) signal.
+- **adc_type** (**Required**, enum):
+
+  - ``external``: Use an external ADC connected to the I²S bus.
+  - ``internal``: Use the internal ADC of the ESP32. Only supported on ESP32, no variant support.
 
 - All other options from :ref:`Microphone <config-microphone>`
 
+External ADC
+------------
+
+- **i2s_din_pin** (**Required**, :ref:`Pin Schema <config-pin_schema>`): The GPIO pin to use for the I²S DIN (Data In) signal.
+- **pdm** (**Required**, boolean): Set this to ``true`` if your external ADC uses PDM (Pulse Density Modulation) instead of I²S.
+
+  .. note::
+
+      PDM microphones are only supported on ESP32 and ESP32-S3.
+
+Internal ADC
+------------
+
+  .. note::
+
+      Internal ADC microphones are only supported on a regular ESP32, not the variants.
+
+- **adc_pin** (**Required**, :ref:`Pin Schema <config-pin_schema>`): The GPIO pin to use for the ADC input.
+
+
+Known Devices
+-------------
+
+M5Stack Atom Echo
+*****************
+
+.. code-block:: yaml
+
+    microphone:
+      - platform: i2s_audio
+        adc_type: external
+        i2s_din_pin: GPIO23
+        pdm: true
+
+RaspiAudio Muse Luxe
+********************
+
+.. code-block:: yaml
+
+    microphone:
+      - platform: i2s_audio
+        i2s_din_pin: GPIO35
+        adc_type: external
+        pdm: false
+
+
 See also
 --------