changed scrolling algorithm to be much more robust, using a state machine instead of state-free processing

firmware/Scroller.cpp

@@ -0,0 +1,129 @@
+/*
+ * Copyright (c) 2019, Ploopy Corporation, a Canadian federal corporation.
+ *
+ * This is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public Licensefalse
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc.
+ * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#include "Scroller.h"
+
+Scroller::Scroller(void) {
+  state = HIHI;
+  lohif = false;
+  hilof = false;
+  lowA = 50;
+  highA = 150;
+  lowB = 50;
+  highB = 150;
+  calculateThreshold(lowA, lowB);
+}
+
+int Scroller::scroll(int curA, int curB) {
+  calculateThreshold(curA, curB);
+
+  bool LO = false;
+  bool HI = true;
+  bool sA, sB;
+  int ret = 0;
+
+  if (curA < scrollThreshold)
+    sA = LO;
+  else
+    sA = HI;
+
+  if (curB < scrollThreshold)
+    sB = LO;
+  else
+    sB = HI;
+
+  if (state == HIHI) {
+    if (sA == LO && sB == HI) {
+      state = LOHI;
+      if (hilof) {
+        ret = 1;
+        hilof = false;
+      }
+    } else if (sA == HI && sB == LO) {
+      state = HILO;
+      if (lohif) {
+        ret = -1;
+        lohif = false;
+      }
+    }
+  }
+
+  else if (state == HILO) {
+    if (sA == HI && sB == HI) {
+      state = HIHI;
+      hilof = true;
+      lohif = false;
+    } else if (sA == LO && sB == LO) {
+      state = LOLO;
+      hilof = true;
+      lohif = false;
+    }
+  }
+
+  else if (state == LOLO) {
+    if (sA == HI && sB == LO) {
+      state = HILO;
+      if (lohif) {
+        ret = 1;
+        lohif = false;
+      }
+    } else if (sA == LO && sB == HI) {
+      state = LOHI;
+      if (hilof) {
+        ret = -1;
+        hilof = false;
+      }
+    }
+  }
+
+  else { // state must be LOHI
+    if (sA == HI && sB == HI) {
+      state = HIHI;
+      lohif = true;
+      hilof = false;
+    } else if (sA == LO && sB == LO) {
+      state = LOLO;
+      lohif = true;
+      hilof = false;
+    }
+  }
+
+  return ret;
+}
+
+int Scroller::getScrollThreshold(void) {
+  return scrollThreshold;
+}
+
+int Scroller::calculateThreshold(int curA, int curB) {
+  if (curA < lowA)
+    lowA = curA;
+  else if (curA > highA)
+    highA = curA;
+
+  if (curB < lowB)
+    lowB = curB;
+  else if (curB > highB)
+    highB = curB;
+
+  int avgA = ((highA - lowA) / 3) + lowA;
+  int avgB = ((highB - lowB) / 3) + lowB;
+
+  scrollThreshold = (avgA + avgB) / 2;
+}

firmware/Scroller.h

@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2019, Ploopy Corporation, a Canadian federal corporation.
+ *
+ * This is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public Licensefalse
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc.
+ * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#ifndef SCROLLER_h
+#define SCROLLER_h
+
+class Scroller {
+  private:
+    enum State { HIHI, HILO, LOLO, LOHI };
+    State state;
+    bool lohif;
+    bool hilof;
+    int lowA;
+    int highA;
+    int lowB;
+    int highB;
+    int scrollThreshold;
+    int calculateThreshold(int, int);
+  public:
+    Scroller(void);
+    int scroll(int, int);
+    int getScrollThreshold(void);
+};
+
+#endif

firmware/production.ino

@@ -21,6 +21,7 @@
 #include <avr/pgmspace.h>
 #include <avr/wdt.h>
 #include "AdvMouse.h"
+#include "Scroller.h"
 
 // Max recommended is 4,000,000, since clock speed is 8MHz.
 // If lower, it should be by factors of 1/2.
@@ -28,7 +29,7 @@ static const int SPIMAXIMUMSPEED = 2000000;
 
 static const int CPI = 1200;
 static const int DEBOUNCE = 10; // ms
-static const int SCROLL_DEBOUNCE = 50; // ms
+static const int SCROLL_DEBOUNCE = 100; // ms
 static const int SCROLL_BUTT_DEBOUNCE = 100; // ms
 
 static const float ROTATIONAL_TRANSFORM_ANGLE = 20;
@@ -45,8 +46,6 @@ static const int SENSOR_CS = 17;
 static const int OPT_ENC_PIN1 = A3;
 static const int OPT_ENC_PIN2 = A5;
 
-static const int OPT_LOW_THRESHOLD = 150;
-
 static const byte MOTION = 0x02;
 static const byte DELTA_X_L = 0x03;
 static const byte DELTA_X_H = 0x04;
@@ -72,8 +71,6 @@ bool buttonState[5] = { false, false, false, false, false };
 uint8_t buttonBuffer[5] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
 char buttonKey[5] = { MOUSE_LEFT, MOUSE_RIGHT, MOUSE_MIDDLE, MOUSE_BACK, MOUSE_FORWARD };
 
-int firstOptLowPin;
-
 bool initComplete = false;
 
 int16_t dx;
@@ -86,6 +83,8 @@ unsigned long lastScroll = 0;
 
 unsigned long middleClickRelease = 0;
 
+static Scroller scroller;
+
 extern const unsigned short firmware_length;
 extern const unsigned char firmware_data[];
 
@@ -401,31 +400,15 @@ signed char moveWheel() {
   int d2 = analogRead(OPT_ENC_PIN2);
 
   if (debugMode) {
-    Serial.print(F("d1: "));
+    Serial.print(F("th: "));
+    Serial.print(scroller.getScrollThreshold());
+    Serial.print(F(", d1: "));
     Serial.print(d1);
     Serial.print(F(", d2: "));
     Serial.println(d2);
   }
 
-  signed char ret = 0;
-
-  if (d1 < OPT_LOW_THRESHOLD && d2 < OPT_LOW_THRESHOLD) {
-    if (firstOptLowPin == OPT_ENC_PIN1) {
-      // scroll down
-      ret = -1;
-    } else if (firstOptLowPin == OPT_ENC_PIN2) {
-      // scroll up
-      ret = 1;
-    }
-
-    firstOptLowPin = 0;
-  } else if (d1 < OPT_LOW_THRESHOLD) {
-    firstOptLowPin = OPT_ENC_PIN1;
-  } else if (d2 < OPT_LOW_THRESHOLD) {
-    firstOptLowPin = OPT_ENC_PIN2;
-  }
-
-  return ret;
+  return scroller.scroll(d2, d1);
 }
 
 void loop() {