USB GPS dongle on UART and Raspberry Pi

I bought this great USB dongle with the ublox Neo-6t chip on it. I want to fit it in a small raspberrypi housing. So I try to connect it not via USB but via the labelled holes on the board. I connected GND to GND, 5V to 5V, TX to RX and RX to TX. I left “INT” empty.

What I expect is that when I type sudo cat /dev/ttyAMA0 I get the GPS data stream directly without USB. When I connect the module via USB I expect getting the same via sudo cat /dev/ttyACM0.

But what happens is strange: When I connect the module without USB I get nothing (but the leds on the module indicate a fix). When I connect the module both with USB and UART I get a reading on ttyAMA0 and ACM0. When I connect USB only I get the reading on ttyACM0 only.

How can I get rid of the USB cable?

The connection seems correct. By default Raspberry Pi has serial console enabled on /dev/ttyAMA0. Did you disable it? It can be done with raspi-config - advanced serial console - disable.

Also, it is necessary to work with a proper baud rate. Default UART baudrate for U-blox NEO-6T is 9600.

The easy way to check if it works (if serial console is disabled) is to use screen like this:

sudo apt-get install screen
sudo screen /dev/ttyAMA0 9600

You should see NMEA or UBX messages coming in. To exit screen press CTRL+A then K then Y.

If it still doesn’t work try switching RX and TX lines.

Thanks. I had serial console disabled with raspi-config. I get the NMEA messages on UART when the USB cable is plugged in but not otherwise.

If anything would be wrong with baud rate I would see unreadable content. But if I disconnect the USB cable I get nothing on ttyAMA0. If TX and RX would be wrong I suppose I would not get anything even if the USB cable would be plugged in.

That’s very strange. Could you please post pictures of how everything is connected and screenshots of what’s going on?