Merge pull request GaudiLabs#3 from Theremingenieur/4.0.1

4.0.1

Software/Open_Theremin_V4/Open_Theremin_V4.ino

@@ -1,6 +1,6 @@
 /*
  *  Open.Theremin control software for Arduino UNO
- *  Version 3.1
+ *  Version 4.0.1
  *  Copyright (C) 2010-2020 by Urs Gaudenz
  *
  *  Open.Theremin control software is free software: you can redistribute it and/or
@@ -31,7 +31,9 @@ ENABLE_SERIAL - if non-0, the build will include code to write the detected
            pitch to the serial connection every 100 milliseconds. Set serial
            receive baud to 115200
 
-ENABLE_CV - if non-0, emit cv output on pin 6 (EXPERIMENTAL!)
+CV_LOG - if non-0, the pitch CV output will follow the Moog/Roland standard 
+          of logarithmic 1V/Octave, else it will follow the linear Korg/Yamaha 
+          standard with 819Hz/V
            
 Structure of the code
 =====================

Software/Open_Theremin_V4/application.cpp

@@ -154,7 +154,7 @@ AppMode Application::nextMode()
 void Application::loop()
 {
   int32_t pitch_v = 0, pitch_l = 0; // Last value of pitch  (for filtering)
-  int32_t vol_v = 0, vol_l = 0;     // Last value of volume (for filtering)
+  int32_t vol_v = 0, vol_l = 0;    // Last value of volume (for filtering and for tracking)
 
   uint16_t volumePotValue = 0;
   uint16_t pitchPotValue = 0;
@@ -163,7 +163,7 @@ void Application::loop()
   uint8_t registerValue = 2;
   uint16_t tmpVolume;
   int16_t tmpPitch;
-  uint8_t tmpOct;
+  uint16_t tmpOct;
   uint16_t tmpLog;
 
 mloop: // Main loop avoiding the GCC "optimization"
@@ -256,7 +256,7 @@ void Application::loop()
 
   if (pitchValueAvailable)
   { // If capture event
-
+    pitch_p = pitch;
     pitch_v = pitch; // Averaging pitch values
     pitch_v = pitch_l + ((pitch_v - pitch_l) >> 2);
     pitch_l = pitch_v;
@@ -273,19 +273,25 @@ void Application::loop()
         tmpPitch = min(tmpPitch, 16383);  // Unaudible upper limit just to prevent DAC overflow
         tmpPitch = max(tmpPitch, 0);      // Silence behing zero beat
         setWavetableSampleAdvance(tmpPitch >> registerValue);
+        if (tmpPitch != pitch_p)
+        { // output new pitch CV value only if pitch value changed (saves runtime resources)
+          pitch_p = tmpPitch;
 #if CV_LOG
-        tmpOct = 0;
-        while (tmpPitch > 1023) {
-          tmpOct += 1;
-          tmpPitch >>= 1;
-        }
-        tmpPitch = max(tmpPitch, 512) - 512;
-        tmpLog = ((uint16_t)tmpPitch >> 3) * 819 >> 6;
-        pitchCV = max(tmpOct * 820 + tmpLog - 48, 0);  // ~1V/Oct for Moog & Roland
+          tmpOct = 0;
+          while (tmpPitch > 1023) {
+            tmpOct += 819;
+            tmpPitch >>= 1;
+          }
+          tmpPitch -= 512;
+          tmpPitch = max(tmpPitch, 0);
+          tmpLog = (((uint32_t)tmpPitch * 819) >> 9);
+          pitchCV = (tmpOct + tmpLog) - 48;
+          pitchCV = max(pitchCV, 0);        // 1V/Oct for Moog & Roland
 #else
-        pitchCV = tmpPitch >> 2;                       // ~800Hz/V for Korg & Yamaha
+          pitchCV = tmpPitch >> 2;                       // 819Hz/V for Korg & Yamaha
 #endif
-        pitchCVAvailable = true;
+          pitchCVAvailable = true;
+        }
         break;
     };
 
@@ -294,8 +300,9 @@ void Application::loop()
     pitchValueAvailable = false;
   }
 
-  if (volumeValueAvailable)
-  {
+  if (volumeValueAvailable && (vol != vol_p))
+  { // If capture event AND volume value changed (saves runtime resources)
+    vol_p = vol;
     vol = max(vol, 5000);
 
     vol_v = vol; // Averaging volume values
@@ -324,6 +331,27 @@ void Application::loop()
     // Give vScaledVolume a pseudo-exponential characteristic:
     vScaledVolume = tmpVolume * (tmpVolume + 2);
 
+    tmpVolume = tmpVolume >> 1;
+
+    if (!gate_p && (tmpVolume >= GATE_ON))
+    {
+      gate_p = true;
+      // pull the gate up to sense, first (to prevent short-circuiting the IO pin:
+      GATE_PULLUP;
+      if (GATE_SENSE)
+      { // if it goes up, drive the gate full high:
+        GATE_DRIVE_HIGH;
+      }
+    }
+    else if (gate_p && (tmpVolume <= GATE_OFF))
+    {
+      gate_p = false;
+      // drive the gate low:
+      GATE_DRIVE_LOW;
+    }
+
+
+
     volumeValueAvailable = false;
   }
 

Software/Open_Theremin_V4/application.h

@@ -29,7 +29,9 @@ class Application {
     static const int16_t VOLUME_POT = 1;
     static const int16_t WAVE_SELECT_POT = 7;
     static const int16_t REGISTER_SELECT_POT = 6;
-
+    int16_t pitch_p = -1; 
+    int32_t vol_p = -1;
+    bool gate_p = false;
 
 
 #if SERIAL_ENABLED    

Software/Open_Theremin_V4/build.h

@@ -10,5 +10,10 @@
 // Set to build with logarithmic 1V/oct pitch control voltage output
 #define CV_LOG 1
 
+// Set the trigger levels for the Gate signal (0 to 127 in preparation for later midi extensions)
+#define GATE_ON  20 // That's the level which will drive the Gate high when volume increases from lower
+#define GATE_OFF 16 // That's the level which will drive the Gate low when volume decreases from higher
+// Making both values equal risk the gate signal to bounce, leave at least 4 (hysteresis) between both.
+// Set both to 128 to disable the Gate Signal.
 
 #endif // _BUILD_H

Software/Open_Theremin_V4/hw.h

@@ -1,3 +1,4 @@
+
 #ifndef _HW_H
 #define _HW_H
 
@@ -14,4 +15,9 @@
 #define HW_LED1_TOGGLE      (PORTC = PORTC ^ (1<<PORTC4))
 #define HW_LED2_TOGGLE      (PORTC = PORTC ^ (1<<PORTC5))
 
+#define GATE_PULLUP         (DDRC &= ~(1<<PORTC2)); (PORTC |= (1<<PORTC2))
+#define GATE_SENSE          (PINC & (1<<PORTC2))
+#define GATE_DRIVE_HIGH     (DDRC |= (1<<PORTC2))
+#define GATE_DRIVE_LOW      (PORTC &= ~(1<<PORTC2)); (DDRC |= (1<<PORTC2))
+
 #endif // _HW_H

Software/Open_Theremin_V4/ihandlers.cpp

@@ -53,7 +53,7 @@ volatile uint16_t vol_counter = 0;
 volatile uint16_t vol_counter_i = 0; // Volume counter
 volatile uint16_t vol_counter_l;     // Last value of volume counter
 
-volatile uint16_t pitchCV;              // Pitch CV value
+volatile int16_t pitchCV;              // Pitch CV value
 volatile uint16_t volCV;                // Volume CV value
 volatile bool volumeCVAvailable;   // Volume CV flag
 volatile bool pitchCVAvailable;    // Pitch CV flag

Software/Open_Theremin_V4/ihandlers.h

@@ -4,7 +4,7 @@
 extern volatile uint16_t pitch;              // Pitch value
 extern volatile uint16_t vol;                // Volume value
 extern volatile uint16_t vScaledVolume;      // Volume byte
-extern volatile uint16_t pitchCV;              // Pitch CV value
+extern volatile int16_t pitchCV;              // Pitch CV value
 extern volatile uint16_t volCV;                // Volume CV value
 
 extern volatile uint16_t pitch_counter;      // Pitch counter