Sparkfun Venus GPS and Arduino

Development Boards Arduino
3

i tried to attach an interrupt to the pin receiving the gps data (pin3, interrupt 0), and it worked.

The state of the input is well changing, but still no data received.

i also tried to loop hardware and softwareSerial as follow:

connecting pin 3 (software rx) to the pin 1 (hardware tx0),

#include <SoftwareSerial.h> 
SoftwareSerial GPS(3,2); //RX,TX

void setup()
{
  Serial.begin(9600);
  GPS.begin(9600);
}
void loop()
{
  if(GPS.available()) Serial.write(GPS.read()); 
  if(Serial.available()) Serial.write(Serial.read()); 
}

void debug(){ Serial.println(micros()); }

i expected to receive a sent char again and again, but i only get it once

I don’t understand why the softwareSerial lib does not provide any data.