Diff: Sensors/IncrementalEncoder/IncrementalEncoder.cpp

Revision:

0:826c6171fc1b

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Sensors/IncrementalEncoder/IncrementalEncoder.cpp	Wed Jun 20 14:57:48 2012 +0000
@@ -0,0 +1,65 @@
+#include "IncrementalEncoder.h"
+
+IncrementalEncoder::IncrementalEncoder(PinName pin):  _lastTicks(0),  _ticks(0), _new(false), _interrupt(pin) {
+    _interrupt.mode(PullNone); // default is pulldown but my encoder board uses a pull-up and that just don't work
+    _interrupt.rise(this, &IncrementalEncoder::_incRise); 
+    _interrupt.fall(this, &IncrementalEncoder::_incFall); 
+    _t.start();
+    _t.reset();
+    _lastTime = _t.read_us();
+}
+
+unsigned int IncrementalEncoder::read() {
+// disable interrupts?
+    unsigned int ticks = _ticks - _lastTicks;
+    _lastTicks = _ticks;
+    _new=false;
+    return ticks;
+}  
+
+unsigned int IncrementalEncoder::readTotal() {
+    _new=false;
+    return _ticks;
+}
+
+unsigned int IncrementalEncoder::readRise() {
+    _new=false;
+    return _rise;
+}  
+
+unsigned int IncrementalEncoder::readFall() {
+    _new=false;
+    return _fall;
+}
+    
+unsigned int IncrementalEncoder::readTime() {
+    return _time;
+}
+    
+void IncrementalEncoder::reset() {
+    _ticks = _lastTicks = 0;
+}  
+
+void IncrementalEncoder::_increment() {
+    _ticks++;
+}
+
+#define A 0.3 // mix in how much from previous readings?
+void IncrementalEncoder::_incRise() {
+    _rise++;
+    _ticks++;
+    _new=true;
+    // compute time between ticks; only do this for rise
+    // to eliminate jitter
+    int now = _t.read_us();
+    _time = A*_time + (1-A)*(now - _lastTime);
+    // Dead band: if _time > xxxx then turn off and wait until next tick
+    // to start up again
+    _lastTime = now;
+}
+
+void IncrementalEncoder::_incFall() {
+    _fall++;
+    _ticks++;
+    _new=true;
+}
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