WP76xx: NMEA output on GPSNMEA SMD channel

Did anyone manage to get NMEA sentences output via the GPSNMEA SMD channel? We are running our own Linux kernel on these modules (no Legato etc) and while we have a driver in place that opens the GPSNMEA SMD channel we can’t get any NMEA sentences out of this channel. Is there some magic involved that activates this NMEA output?

How about the following

echo “$GPS_START” > /dev/nmea
cat /dev/nmea

Thanks, tried that already - but no luck. I think this only works for the EM/MC modules.

How about initiate the gps fix by at!gpsfix and if there is anything on /dev/nmea

GPS autostart enabled. AT!GPSLOC reports the location too but no NMEA output.

Output from ‘cat /sys/kernel/debug/smd/ch’ also shows the SMD channel as open:


10|GPSNMEA |P|APPS |OPENED |0x02000|0x00000|0x00000|DCCiwrsB|0x00000

| | |MDMSW|OPENED |0x02000|0x00000|0x00000|dCciwrsb|0x00000

I tried on WP77 R9, I can see the NMEA frame in “cat /dev/nmea” after the following:

root@fx30:~# gnss start
Success!
root@fx30:~#
root@fx30:~# gnss stop
Success!

Yes, but gnss is a Legato process - and therefore not available to me. If I knew excactly what ‘gnss start’ does … Looks like I will have to dig through the Legato sources …

The platform adaptor for gnss uses QMI on the WP76xx platform. No source code available for that platform adaptor …