Smoothed pot values to reduce jitter

robertgallup · Dec 5, 2018 · 74b23e7 · 74b23e7
1 parent 3c050fa
commit 74b23e7
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Showing 3 changed files with 59 additions and 9 deletions.
diff --git a/DUAL_LFO/DUAL_LFO.ino b/DUAL_LFO/DUAL_LFO.ino
@@ -93,13 +93,13 @@ const double LFO2_FREQ_RANGE =    LFO2_FREQ_MAX - LFO2_FREQ_MIN;
 const double clock = 31372.549;
 
 // LFO 1 controls
-CS_Pot       LFO1_FreqKnob (FREQ1_KNOB_PIN);
-CS_Pot       LFO1_DepthKnob (DEPTH1_KNOB_PIN);
+CS_Pot       LFO1_FreqKnob (FREQ1_KNOB_PIN, 3);
+CS_Pot       LFO1_DepthKnob (DEPTH1_KNOB_PIN, 3);
 CS_Switch    LFO1_WaveSwitch(WAVE1_SWITCH_PIN);
 
 // LFO 2 controls
-CS_Pot       LFO2_FreqKnob (FREQ2_KNOB_PIN);
-CS_Pot       LFO2_DepthKnob (DEPTH2_KNOB_PIN);
+CS_Pot       LFO2_FreqKnob (FREQ2_KNOB_PIN, 3);
+CS_Pot       LFO2_DepthKnob (DEPTH2_KNOB_PIN, 3);
 CS_Switch    LFO2_WaveSwitch (WAVE2_SWITCH_PIN);
 
 // Generic pin state variable
@@ -150,6 +150,13 @@ void setup()
   pinMode(LFO1_OUTPUT_PIN, OUTPUT);     // pin11= PWM:A
   pinMode(LFO2_OUTPUT_PIN, OUTPUT);     // pin 3= PWM:B
 
+  // Initialize knobs
+  LFO1_FreqKnob.begin();
+  LFO1_DepthKnob.begin();
+  LFO2_FreqKnob.begin();
+  LFO2_DepthKnob.begin();
+
+
   // Initialize wave tables
   LFO1_WaveTable = waveTables[0];
   LFO2_WaveTable = waveTables[0];

diff --git a/DUAL_LFO/src/CS_Pot.cpp b/DUAL_LFO/src/CS_Pot.cpp
@@ -29,16 +29,51 @@
 
 #include "CS_Pot.h"
 
+// Macro to increment pointer to circular buffer
+#define next(x) {x+=1;if(x>=_buffLen)x=0;}
+
 // Constructor : clear queues
-CS_Pot::CS_Pot (byte p)
+CS_Pot::CS_Pot (byte p, byte smooth)
 {
+  _smooth = 0;
   _pin = p;
-  value();
+
+  // If smoothing value is in range, initialize smoothing
+  if ((smooth>0)&&(smooth<=MAXSMOOTH)) {
+  	_smooth = smooth;
+
+  	// Buffer length is 2^smooth. Ptr starts at beginning
+  	_buffLen = (1<<_smooth);
+  	_ptr = 0;
+
+  }
+}
+
+// Initialize controls
+void CS_Pot::begin()
+{
+  // Initialize sum and fill buffer with current reading
+  _sum = 0;
+  for (byte i=0; i<_buffLen; i+=1) {
+    _values[i]=analogRead(_pin);
+    _sum += _values[i];
+  }
 }
 
 // Read potentiometer value
 int CS_Pot::value ()
 {
-  return (_lastValue = analogRead(_pin));
+
+  // Take a pot reading. If there's no smoothing, return the raw value
+  int reading = analogRead(_pin);
+  if (0==_smooth) return reading;
+
+  // Otherwise, update the running sum by adding the new value and subtracting the oldest previous value
+  _sum = _sum + reading - _values[_ptr];
+  // Increment the pointer, save the new value, and return the "smoothed" value (divided by 2^smooth)
+  _values[_ptr] = reading;
+  next(_ptr);
+  return (_sum>>_smooth);
+
 }
 
diff --git a/DUAL_LFO/src/CS_Pot.h b/DUAL_LFO/src/CS_Pot.h
@@ -32,18 +32,26 @@
 
 #include "Arduino.h"
 
+#define MAXSMOOTH 3
+
 // CLASS
 class CS_Pot
 {
   public:
 
-    CS_Pot(byte);
+    CS_Pot(byte p, byte smooth=0);
+    void begin();
     int value();
 
   private:
 
-    int  _lastValue;
     byte _pin;
+    byte _smooth;
+
+    int  _sum;
+    byte _ptr;
+    byte _buffLen;
+    int  _values[2<<MAXSMOOTH];
 
 };