Pulse Counter on Arduino - c++

Question

I need a function which returns the number of pulses during a specified time, on arduino.This is the partial code I'm using, but the function isn't retuning anything ( isn't returning even 0 )
...
long Itime = 0;
int Dtime = 25;
...
int Counter() {
unsigned long Ftime = millis();
int c = 0;
int i = 0;
while ( Ftime - Itime < Dtime ) {
if ( digitalRead(PSPin) == HIGH ) {
i=i+1;
while ( digitalRead(PSPin) == HIGH) { // delays the function until
c=c+1; // the next cycle
c=c-1;
}
}
}
Itime = Ftime;
return i;
}
I really don't understand why the function isn't returning 'i'.I'd be happy if someone could help.Thanks
edit:
The signal on PSPin is a 150hz square signal, which means that the period is approximately 6ms, and since my time is 25ms it should return at least 3 pulses..
I called this function for testing purposes only, since I also think my program gets stuck on the Counter() function, but I can't figure out why.
void loop() {
if ( Counter() == 0 )
digitalWrite(TestPinA, HIGH);
if ( Counter() > 0 )
digitalWrite(TestPinB, HIGH);
}
But both pins never return HIGH.
I really appreciate your help.

Answer 1

You are stuck in the
while ( Ftime - Itime < Dtime )
as the code never actually update either of Ftime or Dtime, while in the WHILE loop. Try the following:
int PSPin = 13;
int DurationTime = 25; // best to have same type as compare or cast it later, below.
int Counter() {
int i = 0;
unsigned long StartTime = millis();
unsigned long PrvTime = StartTime ;
while ( PrvTime - StartTime < (unsigned long) DurationTime ) {
if ( digitalRead(PSPin) == HIGH ) {
i=i+1;
while ( digitalRead(PSPin) == HIGH); // BLOCK the function until cycles
}
PrvTime = millis();
}
return i;
}

Answer 2

Use Interrupts to make the work easy.
volatile int IRQcount;
int pin = 2;
int pin_irq = 0; //IRQ that matches to pin 2
void setup() {
// put your setup code here, to run once:
attachInterrupt(pin_irq, IRQcounter, RISING);
delay(25);
detachInterrupt(pin);
Serial.print(F("Counted = ");
Serial.println(IRQcount);
}
void IRQcounter() {
IRQcount++;
}
void loop() {
// put your main code here, to run repeatedly:
}
And if you wanted to use a pin other than INT0/1. You can use PinChangeInt Libray to use any pin.