Odroid-Go: Unmute+Mute buzzer before/after Playback (#52)

On ODROID-GO the buzzer makes noises when it is on and nothing is being played. Don't know if this
is common on ESP32 devices...

internal_filesystem/lib/mpos/audio/audiomanager.py

@@ -31,8 +31,15 @@ class AudioManager:
     STREAM_ALARM = 2         # Alarms/alerts (highest priority)
     
     _instance = None  # Singleton instance
-    
-    def __init__(self, i2s_pins=None, buzzer_instance=None, adc_mic_pin=None):
+
+    def __init__(
+        self,
+        i2s_pins=None,
+        buzzer_instance=None,
+        adc_mic_pin=None,
+        pre_playback=None,
+        post_playback=None,
+    ):
         """
         Initialize AudioManager instance with optional hardware configuration.
 
@@ -40,6 +47,8 @@ class AudioManager:
             i2s_pins: Dict with 'sck', 'ws', 'sd' pin numbers (for I2S/WAV playback)
             buzzer_instance: PWM instance for buzzer (for RTTTL playback)
             adc_mic_pin: GPIO pin number for ADC microphone (for ADC recording)
+            pre_playback: Optional callback called before starting playback
+            post_playback: Optional callback called after stopping playback
         """
         if AudioManager._instance:
             # If instance exists, update configuration if provided
@@ -53,12 +62,15 @@ class AudioManager:
             
         AudioManager._instance = self
 
-        self._i2s_pins = i2s_pins              # I2S pin configuration dict (created per-stream)
-        self._buzzer_instance = buzzer_instance # PWM buzzer instance
-        self._adc_mic_pin = adc_mic_pin         # ADC microphone pin
-        self._current_stream = None             # Currently playing stream
-        self._current_recording = None          # Currently recording stream
-        self._volume = 50                       # System volume (0-100)
+        self._i2s_pins = i2s_pins                # I2S pin configuration dict (created per-stream)
+        self._buzzer_instance = buzzer_instance  # PWM buzzer instance
+        self._adc_mic_pin = adc_mic_pin          # ADC microphone pin
+        self.pre_playback = pre_playback
+        self.post_playback = post_playback
+
+        self._current_stream = None     # Currently playing stream
+        self._current_recording = None  # Currently recording stream
+        self._volume = 50               # System volume (0-100)
 
         # Build status message
         capabilities = []
@@ -68,7 +80,7 @@ class AudioManager:
             capabilities.append("Buzzer (RTTTL)")
         if adc_mic_pin:
             capabilities.append(f"ADC Mic (Pin {adc_mic_pin})")
-        
+
         if capabilities:
             print(f"AudioManager initialized: {', '.join(capabilities)}")
         else:
@@ -131,6 +143,11 @@ class AudioManager:
             stream: Stream instance (WAVStream or RTTTLStream)
         """
         self._current_stream = stream
+        if self.pre_playback:
+            try:
+                self.pre_playback()
+            except Exception as e:
+                print(f"AudioManager: pre_playback callback error: {e}")
 
         try:
             # Run synchronous playback in this thread
@@ -142,6 +159,12 @@ class AudioManager:
             if self._current_stream == stream:
                 self._current_stream = None
 
+            if self.post_playback:
+                try:
+                    self.post_playback()
+                except Exception as e:
+                    print(f"AudioManager: post_playback callback error: {e}")
+
     def play_wav(self, file_path, stream_type=None, volume=None, on_complete=None):
         """
         Play WAV file via I2S.

internal_filesystem/lib/mpos/board/odroid_go.py

@@ -62,9 +62,32 @@ blue_led.on()
 
 print("odroid_go.py init buzzer")
 buzzer = PWM(Pin(BUZZER_PIN, Pin.OUT, value=1), duty=5)
-dac_pin = Pin(BUZZER_DAC_PIN, Pin.OUT, value=1)
-dac_pin.value(1)  # Unmute
-AudioManager(i2s_pins=None, buzzer_instance=buzzer)
+
+
+class BuzzerCallbacks:
+    __slots__ = ("dac_pin",)
+
+    def __init__(self):
+        self.dac_pin = Pin(BUZZER_DAC_PIN, Pin.OUT, value=1)
+
+    def unmute(self):
+        print("Unmute buzzer")
+        self.dac_pin.value(1)  # Unmute
+
+    def mute(self):
+        print("Mute buzzer")
+        self.dac_pin.value(0)  # Mute
+
+
+buzzer_callbacks = BuzzerCallbacks()
+AudioManager(
+    i2s_pins=None,
+    buzzer_instance=buzzer,
+    # The buzzer makes noise when it's unmuted, to avoid this we
+    # mute it after playback and vice versa unmute it before playback:
+    pre_playback=buzzer_callbacks.unmute,
+    post_playback=buzzer_callbacks.mute,
+)
 AudioManager.set_volume(40)
 AudioManager.play_rtttl("Star Trek:o=4,d=20,b=200:8f.,a#,4d#6.,8d6,a#.,g.,c6.,4f6")
 while AudioManager.is_playing():