M4_Eyes: use max peak-to-peak for sound detect

Author: PaintYourDragon

M4_Eyes/pdmvoice.cpp

@@ -61,7 +61,9 @@ static const uint16_t recBufSize       = (uint16_t)(sampleRate / (float)MIN_PITC
 static int16_t        recIndex         = 0;
 static int16_t        playbackIndex    = 0;
 
-volatile uint16_t     voiceLastReading = 0;
+volatile uint16_t     voiceLastReading = 32768;
+volatile uint16_t     voiceMin         = 32768;
+volatile uint16_t     voiceMax         = 32768;
 
 #define DC_PERIOD     4096 // Recalculate DC offset this many samplings
 // DC_PERIOD does NOT need to be a power of 2, but might save a few cycles.
@@ -359,6 +361,12 @@ void PDM_SERCOM_HANDLER(void) {
     // the last thing that was stored prior to whatever time you polled it,
     // but may still have some uses.
     voiceLastReading = adjusted;
+
+    // Similarly, user code can extern these variables and monitor the
+    // peak-to-peak range. They are never reset in the voice code itself,
+    // it's the duty of the user code to reset both to 32768 periodically.
+    if(adjusted < voiceMin)      voiceMin = adjusted;
+    else if(adjusted > voiceMax) voiceMax = adjusted;
   }
   evenWord ^= 1;
 }

M4_Eyes/user_hid.cpp

@@ -3,7 +3,7 @@
 #include <Arduino.h>
 #include "Adafruit_TinyUSB.h"
 #include "globals.h"
-extern volatile uint16_t voiceLastReading; // In pdmvoice.cpp
+extern volatile uint16_t voiceLastReading, voiceMin, voiceMax; // In pdmvoice.cpp
 
 #define UP_BUTTON_KEYCODE_TO_SEND    HID_KEY_U
 #define A_BUTTON_KEYCODE_TO_SEND     HID_KEY_A
@@ -13,7 +13,7 @@ extern volatile uint16_t voiceLastReading; // In pdmvoice.cpp
 // even if not using sound output...we're using it to steal
 // access to the mic here.
 #define SOUND_KEYCODE_TO_SEND        HID_KEY_SPACE
-#define SOUND_THRESHOLD              1000
+#define SOUND_THRESHOLD              10000
 
 // HID report descriptor using TinyUSB's template
 // Single Report (no ID) descriptor
@@ -67,13 +67,14 @@ void user_loop(void) {
     keycode[3] = SHAKE_KEYCODE_TO_SEND;
   }
 
-  if(voiceLastReading) { // usu. non-zero if voice changer enabled
-    int level = abs((int32_t)voiceLastReading - 32768);
-    if(level > SOUND_THRESHOLD) {
+  uint16_t p2p = voiceMax - voiceMin; // Max peak-to-peak since last reading
+  if(p2p) { // usu. non-zero if voice changer enabled
+    if(p2p > SOUND_THRESHOLD) {
       Serial.println("Sound");
       keycode[4] = SOUND_KEYCODE_TO_SEND;
     }
   }
+  voiceMin = voiceMax = 32768; // Reset p2p range for next pass
 
   bool anypressed = false;
   for (int k=0; k<sizeof(keycode); k++) {