GPS module NEO-6M

Other Hardware 3rd Party Boards
1

I have a Neo-6M GPS module which works very well when I connect it to inputs 0 and 1 (RX and TX) with a minimum script (empty setup and loop). NMEA frames appear well on the terminal at 9600 baud.
But if I connect it to inputs 4 (RX) and 3 (TX) and I run the script below, the frames no longer appear, I only see "Setup OK" on the terminal:

SoftwareSerial ss(4, 3);
void setup(){
  Serial.begin(9600);
  ss.begin(9600);
  //setup_display();
  Serial.println("Setup OK");
}

void loop(){
  while (ss.available() > 0){
    // get the byte data from the GPS
    char gpsData = ss.read();
    Serial.write(gpsData);
  }
}

I would like to point out that this assembly worked with my Adruino UNO, I obtained a fairly precise position, but it stopped working. I reset the GPS with U-center, but without success.
Does anyone have an idea of the problem?
2

You say that it worked with a Uno. Which board are you using now ?

3

Still a UNO R3, and I have the same issue with a UNO R4 Wifi

4

Are you certain that you do not have the Rx and Tx lines reversed?

On an UNO R4 WiFi, you do not need SoftwareSerial, it has a separate hardware serial port on pins 0 and 1.

5

The second serial port on pins 0 and 1 of the Uno R4 boards is referred to as Serial1 rather than Serial

6

I'm not sure of anything anymore ! Until now I thought it was necessary to connect the RX pins of the GPS and UNO together and the TX pins together. But it only works if I do the opposite: pin 4(RX of SoftwareSerial)
to TX of GPS and pin 3(TX) to RX of GPS (see attached photo).
Same thing for the UNO R4 with Serial1 by connecting 0 (RX) to the GPS TX and 1(RX) to the TX.
Is it possible that the GPS outputs could have been reversed?
UNO

20240126_221130
20240126_2211301808×1772 229 KB

R4
R4
R41920×1607 259 KB

7

Think about logically and you will see your mistake

The GPS transmits data and the Arduino receives it so Tx on the GPS goes to Rx on the Arduino

8

Yes, now it seems logic to me, but this video : https://www.youtube.com/watch?v=pVcjXIG4KW8 at minute 4'17, tells the opposite.
Anyway, it works now , I am very happy with it !
Thanks a lot for your help and sorry for this beginner's mistake!