Diff: PulsePin.cpp

Revision:

2:6bfef0839102

Child:

4:0d3a207680b0

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/PulsePin.cpp	Fri Nov 07 16:09:15 2014 +0000
@@ -0,0 +1,53 @@
+// Handles a pin that has a slow pulse applied
+// Written for a gas meter monitor
+
+#include "PulsePin.h"
+
+PulsePin::PulsePin(DigitalIn& pin, bool risingEdge, int waitForPinStabilisationMs) :
+    _pin(pin)
+{
+    _risingEdge = risingEdge;
+    _waitForPinStabilisationMs = waitForPinStabilisationMs;
+    _pinTimer.start();
+    _curPinState = _pin;
+    _lastStableTimeMs = _pinTimer.read_ms();
+    _firstEdgeDetected = false;
+    _timeBetweenEdgesMs = 0;
+}
+
+bool PulsePin::Service()
+{
+    // Check time since last edge - looking for stability
+    int timeNowMs = _pinTimer.read_ms();
+    if (timeNowMs < _lastStableTimeMs + _waitForPinStabilisationMs)
+        return false;
+
+    // Check for a change of state
+    bool pinState = _pin;
+    if (pinState == _curPinState)
+        return false;
+        
+    _curPinState = pinState;
+    _lastStableTimeMs = timeNowMs;
+    
+    // Check if this is the direction of edge we're looking for
+    if (pinState != _risingEdge)
+        return false;
+        
+    // Reset the timer to avoid wrap around problems
+    bool firstEdgeDetected = _firstEdgeDetected;
+    _pinTimer.reset();
+    _firstEdgeDetected = true;
+    _lastStableTimeMs = 0;
+    
+    // Check if this should be returned
+    if (!firstEdgeDetected)
+        return false;
+    _timeBetweenEdgesMs = timeNowMs;
+    return true;
+}
+
+int PulsePin::GetLastCycleTimeMs()
+{
+    return _timeBetweenEdgesMs;
+}