From 1f1b56dd6b8e71c5a8d2f9e360092e8167ec6416 Mon Sep 17 00:00:00 2001
From: Alexander Kauerz <kauerz@informatik.uni-luebeck.de>
Date: Wed, 15 Feb 2012 22:01:28 +0100
Subject: Wilde Dinge von Arduino.cc querkopiert. Stichwort: RotaryEncoders

---
 Drehimpulsgeber/drehimp.cpp | 108 +++++++++++++++++++++++++++++++++++---------
 1 file changed, 87 insertions(+), 21 deletions(-)

(limited to 'Drehimpulsgeber/drehimp.cpp')

diff --git a/Drehimpulsgeber/drehimp.cpp b/Drehimpulsgeber/drehimp.cpp
index 4f64629..bcd38b8 100644
--- a/Drehimpulsgeber/drehimp.cpp
+++ b/Drehimpulsgeber/drehimp.cpp
@@ -1,28 +1,94 @@
 #include <Arduino.h>
 
-void doCount0();
-void doCount1();
-
-volatile int cnt0 = 0; // Digitaler Pin 2 und 3
-volatile int cnt1 = 0;
-
-void setup()
-{ 
-  digitalWrite(2, HIGH);
-  digitalWrite(3, HIGH);
-  attachInterrupt(0, doCount0, CHANGE);
-  attachInterrupt(1, doCount1, CHANGE);
-  Serial.begin(9600);
+/* interrupt routine for Rotary Encoders
+   tested with Noble RE0124PVB 17.7FINB-24 http://www.nobleusa.com/pdf/xre.pdf - available at pollin.de
+   and a few others, seems pretty universal
+
+   The average rotary encoder has three pins, seen from front: A C B
+   Clockwise rotation A(on)->B(on)->A(off)->B(off)
+   CounterCW rotation B(on)->A(on)->B(off)->A(off)
+
+   and may be a push switch with another two pins, pulled low at pin 8 in this case
+   raf@synapps.de 20120107
+
+*/
+
+// usually the rotary encoders three pins have the ground pin in the middle
+enum PinAssignments {
+  encoderPinA = 2,   // rigth
+  encoderPinB = 3,   // left
+  clearButton = 8    // another two pins
+};
+
+volatile unsigned int encoderPos = 0;  // a counter for the dial
+unsigned int lastReportedPos = 1;   // change management
+static boolean rotating=false;      // debounce management
+
+// interrupt service routine vars
+boolean A_set = false;              
+boolean B_set = false;
+
+
+void setup() {
+
+  pinMode(encoderPinA, INPUT); 
+  pinMode(encoderPinB, INPUT); 
+  pinMode(clearButton, INPUT);
+ // turn on pullup resistors
+  digitalWrite(encoderPinA, HIGH);
+  digitalWrite(encoderPinB, HIGH);
+  digitalWrite(clearButton, HIGH);
+
+// encoder pin on interrupt 0 (pin 2)
+  attachInterrupt(0, doEncoderA, CHANGE);
+// encoder pin on interrupt 1 (pin 3)
+  attachInterrupt(1, doEncoderB, CHANGE);
+
+  Serial.begin(9600);  // output
+}
+
+// main loop, work is done by interrupt service routines, this one only prints stuff
+void loop() { 
+  rotating = true;  // reset the debouncer
+
+  if (lastReportedPos != encoderPos) {
+    Serial.print("Index:");
+    Serial.println(encoderPos, DEC);
+    lastReportedPos = encoderPos;
+  }
+  if (digitalRead(clearButton) == LOW )  {
+    encoderPos = 0;
+  }
+}
+
+// Interrupt on A changing state
+void doEncoderA(){
+  // debounce
+  if ( rotating ) delay (1);  // wait a little until the bouncing is done
+
+  // Test transition, did things really change? 
+  if( digitalRead(encoderPinA) != A_set ) {  // debounce once more
+    A_set = !A_set;
+
+    // adjust counter + if A leads B
+    if ( A_set && !B_set ) 
+      encoderPos += 1;
+
+    rotating = false;  // no more debouncing until loop() hits again
+  }
 }
 
-void loop()
-{ Serial.print(cnt0);
-  Serial.print(" - ");
-  Serial.println(cnt1);
-  delay(1000);
+// Interrupt on B changing state, same as A above
+void doEncoderB(){
+  if ( rotating ) delay (1);
+  if( digitalRead(encoderPinB) != B_set ) {
+    B_set = !B_set;
+    //  adjust counter - 1 if B leads A
+    if( B_set && !A_set ) 
+      encoderPos -= 1;
+
+    rotating = false;
+  }
 }
 
-// Dummy interrupt functions
-void doCount0() {cnt0++;}
-void doCount1() {cnt1++;}
 
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