add gain=2, non-blocking operation, led abstracted

Metro.cpp

@@ -0,0 +1,61 @@
+
+
+#if defined(ARDUINO) && ARDUINO >= 100
+#include "Arduino.h"
+#else
+#include "WProgram.h"
+#endif
+#include "Metro.h"
+
+Metro::Metro()
+{
+	
+	this->interval_millis = 1000;
+	
+}
+
+
+Metro::Metro(unsigned long interval_millis)
+{
+	
+	this->interval_millis = interval_millis;
+	
+}
+
+
+void Metro::interval(unsigned long interval_millis)
+{
+  this->interval_millis = interval_millis;
+}
+
+uint8_t Metro::check()
+{
+
+  unsigned long now = millis();
+  
+  if ( interval_millis == 0 ){
+    previous_millis = now;
+	return 1;
+  }
+ 
+  if ( (now - previous_millis) >= interval_millis) {
+	#ifdef NOCATCH-UP
+	previous_millis = now ; 
+	#else
+	previous_millis += interval_millis ; 
+	 #endif
+    return 1;
+  }
+  
+  return 0;
+
+}
+
+void Metro::reset() 
+{
+ 
+  this->previous_millis = millis();
+
+}
+
+