GPS with asset_tracker application on nRF9160 DK

[ERIK]

I hear that the GPS should now work with the onboard antenna of the nRF9160 DK for versions 0.8.5 and later.  I also read that the asset_tracker application has been updated in the Master to work with this as well.

I am using a DK board v0.8.5.  I have SES 4.20a.  I have the master from git as of 9/21/19.

I took the asset tracker application and in the menuconfig project configuration for the application, I changed to the user GPS selection:

Is that correct?

I see that the GPS device name below that is set to GPS_SIM.  Do I need to change that?

In the config for the Zephyr Kernel, there are GPS device driver options that reference GPS simulation.  Do those need modification as well?

I've also heard/read that at this time, GPS will ONLY work with PSM.  Is that correct? 

Because of this, I have also enabled power optimization so that PSM (or eDRX) can be used with asset_tracker, as noted in the asset_tracker description in the SDK

With these changes, I rebuilt the solution and loaded it on my DK.

The SDK asset_tracker description says

So, I set SW2 to the N/C position when running the asset_tracker application.

It connects to the LTE network just fine, and I can push button 1 and see that info show up in nRF Cloud fine.  But it still shows the asset as being at Nordic Semiconductor in Norway.

I will admit to a lack of understanding of a lot of PSM.  I don't know how to tell if the modem is requesting to go into PSM sleep, when that will happen, or how long it will stay asleep.  Can you point me at documentation for that and, in the short term, tell me how to check or resolve here?

On top of this, I'm seeing some issues where after some time of running, the application stops responding or resets.  Unsure of the cause there.  I know in the past, with older versions of the SDK and modem firmware, the board would reset if I toggled SW2 on and off again, so in the past I've left it off (GND). Unsure if this is related.

Can you please advise?  I haven't been able to find a comprehensive description of how to get the GPS working in any one thread on DevZone, so thought I'd ask myself.

Thanks,

Erik

[Didrik Rokhaug]

Hi.

Try to set "GPS device name" to "NRF9160_GPS" instead of "GPS_SIM".

I've also heard/read that at this time, GPS will ONLY work with PSM.  Is that correct? 

 You cannot receive any GPS signals when using the LTE antenna. Therefore, if you want to use LTE and GPS together, you need PSM.

A device can request PSM, specifying the requested Periodic Tracking Area Update (P-TAU, the interval when the antenna is off), and Active-Time (the interval after a transmit when the device can be reached/is receiving). It is up to the network if the request is granted. If you are using the iBasis SIM card that came with the DK, my guess is that PSM is not granted (I only know of places where that is not granted, and no places where it is granted).

Looking at the configuration for the Thingy:91 (https://github.com/NordicPlayground/fw-nrfconnect-nrf/blob/master/applications/asset_tracker/prj_nrf9160_pca20035ns.conf), they do not enable power optimization, so I do not think it is necessary, although I have not tried to use GPS with asset tracker myself as I cannot enable PSM.

Best regards,

Didrik

[ERIK]

I am using the iBasis SIM and it is connecting to Verizon towers.  I have heard that iBasis SIM cards are prevented from using PSM on Verizon.  Is that correct?  Will that be changing?

[Didrik Rokhaug]

I have been unable to confirm whether iBasis SIM cards are allowed PSM on Verizon networks or not. However, I do know that on Verizon networks only PSM periods of >190 minutes are allowed.

You can check if PSM got activated by using AT+CEREG=5 or AT%XMONITOR. If the first three bits of the Active-time or Periodic-TAU is 111, PSM the related timer is not activated.