codal_app: Use uBit.audio.level for sound level detector.

And only register the event callback when the microphone is needed.  This
way the microphone is not initialised until needed by the code.  And the
settings are the standard ones defined by uBit.

Fixes issue #107.

Signed-off-by: Damien George <damien@micropython.org>

Author: dpgeorge

src/codal_app/main.cpp

@@ -32,7 +32,6 @@ extern "C" void mp_main(void);
 extern "C" void m_printf(...);
 extern "C" void microbit_hal_timer_callback(void);
 extern "C" void microbit_hal_gesture_callback(int);
-extern "C" void microbit_hal_level_detector_callback(int);
 extern "C" void microbit_hal_sound_synth_callback(int);
 extern "C" void microbit_radio_irq_handler(void);
 
@@ -46,10 +45,6 @@ void gesture_event_handler(Event evt) {
     microbit_hal_gesture_callback(evt.value);
 }
 
-void level_detector_event_handler(Event evt) {
-    microbit_hal_level_detector_callback(evt.value);
-}
-
 void sound_synth_event_handler(Event evt) {
     microbit_hal_sound_synth_callback(evt.value);
 }
@@ -68,7 +63,6 @@ int main() {
     uBit.messageBus.listen(MICROPY_TIMER_EVENT, DEVICE_EVT_ANY, timer_handler, MESSAGE_BUS_LISTENER_IMMEDIATE);
     uBit.messageBus.listen(DEVICE_ID_SERIAL, CODAL_SERIAL_EVT_DELIM_MATCH, serial_interrupt_handler, MESSAGE_BUS_LISTENER_IMMEDIATE);
     uBit.messageBus.listen(DEVICE_ID_GESTURE, DEVICE_EVT_ANY, gesture_event_handler);
-    uBit.messageBus.listen(DEVICE_ID_SYSTEM_LEVEL_DETECTOR, DEVICE_EVT_ANY, level_detector_event_handler);
     uBit.messageBus.listen(DEVICE_ID_SOUND_EMOJI_SYNTHESIZER_0, DEVICE_EVT_ANY, sound_synth_event_handler);
 
     // 6ms follows the micro:bit v1 value

src/codal_app/microbithal_microphone.cpp

@@ -28,44 +28,38 @@
 #include "microbithal.h"
 #include "MicroBitDevice.h"
 
-extern "C" {
-
 #define SOUND_LEVEL_MAXIMUM (20000)
 
-static NRF52ADCChannel *mic = NULL;
-static StreamNormalizer *processor = NULL;
-static LevelDetector *level = NULL;
+extern "C" void microbit_hal_level_detector_callback(int);
 
-void microbit_hal_microphone_init(void) {
-    if (mic == NULL) {
-        mic = uBit.adc.getChannel(uBit.io.microphone);
-        mic->setGain(7, 0);
+static void level_detector_event_handler(Event evt) {
+    microbit_hal_level_detector_callback(evt.value);
+}
 
-        processor = new StreamNormalizer(mic->output, 0.05, true, DATASTREAM_FORMAT_8BIT_SIGNED);
-        level = new LevelDetector(processor->output, 600, 200);
+extern "C" {
 
-        uBit.io.runmic.setDigitalValue(1);
-        uBit.io.runmic.setHighDrive(true);
+static bool microphone_init_done = false;
+
+void microbit_hal_microphone_init(void) {
+    if (!microphone_init_done) {
+        microphone_init_done = true;
+        uBit.messageBus.listen(DEVICE_ID_SYSTEM_LEVEL_DETECTOR, DEVICE_EVT_ANY, level_detector_event_handler);
     }
 }
 
 void microbit_hal_microphone_set_threshold(int kind, int value) {
     value = value * SOUND_LEVEL_MAXIMUM / 255;
     if (kind == 0) {
-        level->setLowThreshold(value);
+        uBit.audio.level->setLowThreshold(value);
     } else {
-        level->setHighThreshold(value);
+        uBit.audio.level->setHighThreshold(value);
     }
 }
 
 int microbit_hal_microphone_get_level(void) {
-    if (level == NULL) {
-        return -1;
-    } else {
-        int l = level->getValue();
-        l = min(255, l * 255 / SOUND_LEVEL_MAXIMUM);
-        return l;
-    }
+    int l = uBit.audio.level->getValue();
+    l = min(255, l * 255 / SOUND_LEVEL_MAXIMUM);
+    return l;
 }
 
 }