External GPS not working

Hello all. I have been trying to connect an external GPS over USB as described in the docs.

I put line /home/pi/APMrover2.elf -A udp: -C /dev/ttyAMA0 -E /dev/ttyUSB0 & in my /etc/rc.local file and APM starts up on boot. I get telemetry to GCS over uart radio. I get wifi connection for SSH. I get GPS1 (built-in) but I get no GPS2 data in the GCS. Both GPS are set to auto. I can confirm that data is coming in because if I type

screen /dev/ttyUSB0 I see line of garbage characters. So the GPS is sending something. I have no idea how to make the garbage chars readable. Inverted mode ?

I am assuming the the USB0 comes in over serial 3. Is this correct ?

Anyone have any ideas ? Thanks.

I kind of did a work around here. I put the telemetry radio on USB -C /dev/ttyUSB0 and put the external GPS on the uart with -E/dev/ttyAMA0. The uart brings the data over serial 3 and voila! it shows up on MP as the second GPS. BTW in the developer examples GPS.py does not work but gps.cpp works fine.

Thank you for the report. We’ll try to repro and get back ASAP.

Hi vinorobo,

Sorry for the late response!

Could you please provide some photos of your hardware setup?
What external GPS do you use?

Please try to run screen with different baud rates (e.g., 38400, 57600, 115200). For example ‘screen /dev/ttyUSB0 115200’.

-E switch mapped to serial 4 as described here.

Both examples work fine and I can’t reproduce this issue.
How did you run GPS.py? Have you made changes in the source code?

Hello there!

Did you get a chance to try the above mentioned suggestions?

You may close this topic. Thanks.