Add microphone.set_sensitivity example and js hal

src/board/audio/index.ts

@@ -22,6 +22,7 @@ export class BoardAudio {
   private oscillator: OscillatorNode | undefined;
   private volumeNode: GainNode | undefined;
   private muteNode: GainNode | undefined;
+  private sensitivityNode: GainNode | undefined;
 
   default: BufferedAudio | undefined;
   speech: BufferedAudio | undefined;
@@ -46,6 +47,11 @@ export class BoardAudio {
       this.context.currentTime
     );
     this.muteNode.connect(this.context.destination);
+    this.sensitivityNode = this.context.createGain();
+    this.sensitivityNode.gain.setValueAtTime(
+      0.2, // sensitivity medium level
+      this.context.currentTime
+    );
     this.volumeNode = this.context.createGain();
     this.volumeNode.connect(this.muteNode);
 
@@ -133,6 +139,14 @@ export class BoardAudio {
     }
   }
 
+  setSensitivity(sensitivity: number) {
+    this.sensitivityNode!.gain.setValueAtTime(
+      // check if this is correct
+      sensitivity, 
+      this.context!.currentTime
+    )
+  }
+
   setVolume(volume: number) {
     this.volumeNode!.gain.setValueAtTime(
       volume / 255,
@@ -195,9 +209,7 @@ export class BoardAudio {
     this.microphoneEl.style.display = "unset"
 
     const source = this.context!.createMediaStreamSource(micStream);
-    // TODO: wire up microphone sensitivity to this gain node
-    const gain = this.context!.createGain();
-    source.connect(gain);
+    source.connect(this.sensitivityNode!);
     // TODO: consider AudioWorklet - worth it? Browser support?
     //       consider alternative resampling approaches
     //       what sample rates are actually supported this way?
@@ -222,12 +234,12 @@ export class BoardAudio {
       });
       offlineContext.startRendering();
     };
-    gain.connect(recorder);
+    this.sensitivityNode!.connect(recorder);
     recorder.connect(this.context!.destination);
 
     this.stopActiveRecording = () => {
       recorder.disconnect();
-      gain.disconnect();
+      this.sensitivityNode!.disconnect();
       source.disconnect();
       micStream.getTracks().forEach(track => track.stop())
       this.microphoneEl.style.display = "none"

src/demo.html

@@ -90,6 +90,7 @@ <h1>MicroPython-micro:bit simulator example embedding</h1>
               <option value="display">Display</option>
               <option value="inline_assembler">Inline assembler</option>
               <option value="microphone">Microphone</option>
+              <option value="microphone_sensitivity">Microphone sensitivity</option>
               <option value="music">Music</option>
               <option value="pin_logo">Pin logo</option>
               <option value="pin_touches">Pin touches</option>

src/examples/microphone_sensitivity.py

@@ -0,0 +1,30 @@
+from microbit import microphone, audio, button_a, button_b, pin_logo
+
+sensitivities = [
+    microphone.SENSITIVITY_LOW, 
+    microphone.SENSITIVITY_MEDIUM, 
+    microphone.SENSITIVITY_HIGH
+]
+sensitivity_index = 0
+
+print("Recording...")
+frame = microphone.record(3000)
+print("Button A to play")
+print("Button B to record")
+print("Logo to change sensitivity")
+
+while True:
+    if button_a.was_pressed():
+        print("Start playing")
+        audio.play(frame, wait=True)
+        print("Playing ended")
+
+    if button_b.was_pressed():
+        print("Recording...")
+        frame = microphone.record(3000)
+
+    if pin_logo.was_touched():
+        sensitivity_index = (sensitivity_index + 1) % len(sensitivities)
+        print("Sensitivity change to", sensitivities[sensitivity_index])
+        microphone.set_sensitivity(sensitivities[sensitivity_index])
+

src/jshal.h

@@ -83,6 +83,7 @@ void mp_js_hal_audio_stop_expression(void);
 bool mp_js_hal_audio_is_expression_active(void);
 
 void mp_js_hal_microphone_init(void);
+void mp_js_hal_microphone_set_sensitivity(float value);
 void mp_js_hal_microphone_set_threshold(int kind, int value);
 int mp_js_hal_microphone_get_level(void);
 void mp_js_hal_microphone_start_recording(uint8_t *buf, size_t max_len, size_t *cur_len, int rate);

src/jshal.js

@@ -278,6 +278,11 @@ mergeInto(LibraryManager.library, {
     Module.board.microphone.microphoneOn();
   },
 
+  mp_js_hal_microphone_set_sensitivity: function (
+    /** @type {number} */ value
+  ) {
+    Module.board.audio.setSensitivity(value)
+  },
   mp_js_hal_microphone_set_threshold: function (
     /** @type {number} */ kind,
     /** @type {number} */ value

src/microbithal_js.c

@@ -484,6 +484,14 @@ void microbit_hal_microphone_init(void) {
     */
 }
 
+void microbit_hal_microphone_set_sensitivity(float value)
+{
+    mp_js_hal_microphone_set_sensitivity(value);
+    /*
+    uBit.audio.processor->setGain(value);
+    */
+}
+
 void microbit_hal_microphone_set_threshold(int kind, int value) {
     mp_js_hal_microphone_set_threshold(kind, value);
     /*