We have been evaluating the nRF9160 using the nRF9160-DK. After some effort we have many functions working, and now require synchronisation. I was disappointed to find that the GPS function does not provide a standard PPS (pulse-per-second) signal. All attempts to find a resolution result in dead-ends like this one:
This is despite the Product Specification claiming PPS is supported:
When internal GPS is used, COEX1 delivers the GPS 1PPS (one pulse per second) time mark pulse.
By coincidence I noticed that v1.3.0 of the modem firmware, released earlier this month, makes reference to this signal. The release notes state:
- GNSS time based configurable timing pulse output on COEX1 IO-pin. Feature can be utilized by using new nRF Connect SDK socket option.
But I can find no corresponding reference in the nRF Connect SDK (with particular attention to nrfxlib/nrf_modem). Nor can I find anything relevant in the AT command documentation, despite it claiming to have been updated to suit the v1.3.0 firmware.
I have now applied the v1.3.0 modem firmware and can confirm that the new AT command to control the COEX2 now works. I tried guessing the equivalent COEX1 command, but no luck:
AT%HWVERSION
%HWVERSION: nRF9160 SICA B1A
OK
AT%XCOEX2?
%XCOEX2:
OK
AT%XCOEX1?
ERROR
For what it's worth, given that the GPS is integrated, I'd prefer to have access to an interrupt driven directly by PPS. But if I really have to wire from the COEX1 pin back into a GPIO pin, I will make do.
Given we seem to have reached the end of publicly available information to support ourselves, I've also lodged this support request with our distributor. I'm posting it publicly here too in case it helps find the right person.
Cheers,
Heath
