 Output duty cycle: 50% +-10%
 Output rise time: 0.04us
 Output fall time: 0.18us
-Flow rate pulse characteristics: Frequency (Hz) = 7.5 * Flow rate (L/min)
-Pulses per Liter: 450
+Flow rate pulse characteristics: 
+Flow rate: 1 pulse/s = 7.5 L/min
+Acumulated volume: 1 Liter = 450 pulses
+maximum pulse frequency: 30 L/min-> 225 imp/s -> min period 4.44 ms  (delta 0.1 L/min->0.015 ms)
+                          5 L/min-> 37.5 imp/s->     period 26.66 ms (delta 0.1 L/min->0.523 ms)
+minimun pulse frequency:  1 L/min-> 7.5 imp/s -> max period 133.3 ms (delta 0.1 L/min->12.1 ms)
 Durability: minimum 300,000 cycles
 Mechanical:
 1/2" NPS nominal pipe connections, 0.78" outer diameter, 1/2" of thread

#include "PulseSensor.h"


#define REFRESH_INTERVAL  1000      // refresh time, 1 second
#define WRITE_INTERVAL 5000  // values send to serial port, 5 seconds (5 * 1000)
#define PULSE_PIN 18 // see external interrupt pins available on your Arduino.
                     // Conect an external 10 Kohm pull up resistor  on input pin is recomended
#define PULSES_SEC_2_LITERS_MINUTE 7.5 // conversion factor from pulses/second to liters/minute
#define PULSES_2_LITERS 450 // conversion factor from pulses to liters
PulseSensor flowmeter; // instance to collect data
//variables to process and send values
float flowRate;
float maxRate;

/**********************************************************************/
/* Flowmeter example
/* An example to collect data from a flowmeter using PulseSensor class
/* version 0.3 BETA 22/09/2015
/* Author: Jaime García  @peninquen
/* Licence: Apache License Version 2.0.
/*
