add debug messages to audio

quantum/audio/audio.c

@@ -106,6 +106,8 @@ void audio_init()
 
 void stop_all_notes()
 {
+    dprintf("audio stop all notes");
+
     if (!audio_initialized) {
         audio_init();
     }
@@ -128,6 +130,8 @@ void stop_all_notes()
 
 void stop_note(float freq)
 {
+    dprintf("audio stop note freq=%d", (int)freq);
+
     if (playing_note) {
         if (!audio_initialized) {
             audio_init();
@@ -312,6 +316,8 @@ ISR(TIMER3_COMPA_vect)
 
 void play_note(float freq, int vol) {
 
+    dprintf("audio play note freq=%d vol=%d", (int)freq, vol);
+
     if (!audio_initialized) {
         audio_init();
     }