FreqCounter, any way to use PWM pins as normal pins?

Using Arduino Sensors
10

I think it's solved. At least for now ...

finally the solution was to simply 'close' the SoftwareSerial session before reading the photodiodes with the end() method.
It seems that SoftwareSerial (which uses arduino timers) doesn't work together with FreqCounter (which uses also timers).
It modifies the freq. reported by FreqCounter

void loop(){
  // software serial code (defined on pins 2=RX & 3=TX, seems to affect TSLs on pins 5-7)
  softserial.begin(9600);
  softserial.flush();
  do_something();
  softserial.end()

  photometer_reading(); // the code I posted before.
}