GPSMON and nRF52840 Connectivity Bridge

[John_Turner]

Hi,

I'm trying to use the GNSS application for the nRF9160 to compare GPS antenna performance. There is a Linux utility, GPSMON, that I'm trying to use to display side by side performance of different GPS receivers, and identical receivers with different antennas. GPSMON will recognize the output of the nRF9160 on a development board but not the output of an nRF52840 programmed with the connectivity bridge software. There doesn't seem to be any difference in the data when viewed in terminal programs.

I'm looking for any ideas on why the connectivity bridge software doesn't work in this scenario?

JT

[Albrecht Markus Schellenberger]

Hello John, 

I'm looking for any ideas on why the connectivity bridge software doesn't work in this scenario?

The Connectivity bridge is designed to act as an USB composite device for the Thingy:91. The nRF52840 does not support GNSS functionality on its own. 

Regards, 

Markus 

[John_Turner]

Hello Markus,

As clarification, I am running the GNSS application on the nRF9160 in two different scenarios. The first is on an nRF9160DK and in the second on custom hardware that mimics the Thingy91 hardware, e.g. using the nRF52840 to provide the serial interface over USB. In both cases I can view the NMEA sentences and the information is correct. However, when I run the application on the nRF9160DK the serial output is recognized by GPSMON but if I run it on the custom hardware, with the connectivity bridge, it is not. Since the nRF9160DK uses a different serial to USB converter then the Thingy91 my assumption is that this is where the issue lies.

One suggestion is that there is a difference in the implementation of hardware flow control between the two platforms. Do both the nRF9160Dk and the connectivity bridge software both use hardware flow control?

JT 

[Albrecht Markus Schellenberger]

Hello John, 

John_Turner said:

Do both the nRF9160Dk and the connectivity bridge software both use hardware flow control?

Yes, they do. See:

• Thingy:91 pin assignment
• nRF9160 DK pin assignment
  

John_Turner said:

However, when I run the application on the nRF9160DK the serial output is recognized by GPSMON but if I run it on the custom hardware, with the connectivity bridge, it is not. Since the nRF9160DK uses a different serial to USB converter then the Thingy91 my assumption is that this is where the issue lies.

The nRF9160 DK has the Segger OB debugger available through the USB, which the Thingy:91 hasn’t. Hence, Thingy:91 can only be programmed in MCUboot mode via USB. Unfortunately, it is hard to tell what the reason could be here. I assume you are using the latest revision of the Connectivity bridge on your nRF52840? 

Regards,

Markus

[John_Turner]

Hi Markus,

The connectivity bridge was built from SDK version 1.71 using the Segger IDE. I've tried to rebuild it with a later version but I get python and script errors when I try to import the project. Hopefully version 2.0 of the SDK and VS Code will be less problematic. 

As far as I can tell everything on the Nordic side is working as expected. I'm going to assume that the issue is with the GPSMON code so I think the case can be closed.

JT

[Albrecht Markus Schellenberger]

John_Turner said:

As far as I can tell everything on the Nordic side is working as expected. I'm going to assume that the issue is with the GPSMON code so I think the case can be closed.

Thanks a lot for your feedback, John! 

My personal recommendation would be to investigate the GPSMON side as well. But feel free to create a new ticket if that does not give the desired results :-)

Cheers, 

Markus