Diff: DebouncedFallingEdgeCounter.cpp

Revision:

0:457832d52954

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/DebouncedFallingEdgeCounter.cpp	Sat Feb 25 03:23:51 2012 +0000
@@ -0,0 +1,100 @@
+/* Copyright 2012 Adam Green (http://mbed.org/users/AdamGreen/)
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+/* Implementation for wrapper class of InterruptIn used for counting falling edge
+   events with specified hold off time for the purpose of debouncing.
+*/
+#include <mbed.h>
+#include "DebouncedFallingEdgeCounter.h"
+
+
+CDebouncedFallingEdgeCounter::CDebouncedFallingEdgeCounter(PinName InterruptInPin, unsigned int IgnoreTimeForDebounceInMicroSeconds) 
+    : m_FallingEdgeInterruptIn(InterruptInPin)
+{
+    m_Timer.start();
+    m_IgnoreTimeForDebounce = IgnoreTimeForDebounceInMicroSeconds;
+    InitLastFallingEdgeTime();
+
+    ZeroCount();
+
+    m_FallingEdgeInterruptIn.mode(PullUp);
+    m_FallingEdgeInterruptIn.fall<CDebouncedFallingEdgeCounter>(this, &CDebouncedFallingEdgeCounter::FallingEdgeISR);
+}
+
+
+void CDebouncedFallingEdgeCounter::InitLastFallingEdgeTime()
+{
+    InitLastFallingEdgeTime((unsigned int)m_Timer.read_us());
+}
+
+
+void CDebouncedFallingEdgeCounter::InitLastFallingEdgeTime(unsigned int CurrentTime)
+{
+    m_LastFallingEdgeTime = CurrentTime - m_IgnoreTimeForDebounce;
+}
+
+
+void CDebouncedFallingEdgeCounter::FallingEdgeISR()
+{
+    // UNDONE: Can I just use whatever timer the m_Timer uses under the covers?
+    unsigned int CurrentTime = (unsigned int)m_Timer.read_us();
+    
+    if (TimeSinceLastFallingEdge(CurrentTime) >= m_IgnoreTimeForDebounce)
+    {
+        m_FallingEdgeCount++;
+        m_LastFallingEdgeTime = CurrentTime;
+    }
+}
+
+
+unsigned int CDebouncedFallingEdgeCounter::TimeSinceLastFallingEdge(unsigned int CurrentTime)
+{
+    return CurrentTime - m_LastFallingEdgeTime;
+}
+
+
+unsigned int CDebouncedFallingEdgeCounter::GetCountAndZero()
+{
+    unsigned int CurrentCount;
+    
+    CurrentCount = GetCount();
+    ZeroCount();
+    return CurrentCount;
+}
+
+
+unsigned int CDebouncedFallingEdgeCounter::GetCount()
+{
+    RefreshTimers();
+    
+    return m_FallingEdgeCount;
+}
+
+
+void CDebouncedFallingEdgeCounter::ZeroCount()
+{
+    m_FallingEdgeCount = 0;
+}
+
+
+void CDebouncedFallingEdgeCounter::RefreshTimers()
+{
+    unsigned int CurrentTime = (unsigned int)m_Timer.read_us();
+    
+    if (TimeSinceLastFallingEdge(CurrentTime) > m_IgnoreTimeForDebounce)
+    {
+        // Protect from timer overflow.
+        InitLastFallingEdgeTime(CurrentTime);
+    }
+}