On-demand mode and support Fibocom NL687-E

[slydiman]

I have investigated the following GPS related AT commands for the modem Fibocom NL687-E

AT+GPSCFG=20,180,9999999,1,2,7
  QOS_T: (1-100)
  QOS_ST: (1-255)
  Num_fix: (1-9999999)
  Time_fix: (1-65535)
  Session_type: (0-5)
  Svc_type: (1-7)
AT+GPSCFG?
+GPSCFG:QOS_T:20,QOS_ST:180,Num_fix:9999999,Time_fix:1000,Session_type:2,Svc_type:7,

AT+GTAGPSSERV: (<IP/URL>),(1-65535)

AT+GTGPSSET  (always ERROR)

AT+GPSMODE: (0-7)
AT+GPSMODE?
+GPSMODE:0

AT+GTGPSEPO: (0-1)
AT+GTGPSEPO?
+GTGPSEPO:1

AT+GPSSTART (always ERROR)

AT+GPSEND

AT+GTGPSPOWER: (0-1)

AT+GTGPS:"RMC","GGA","GSA","GSV","GST"

The default USB mode is 17 (AT+GTUSBMODE=17): Diag (ttyUSB0)+Modem (ttyUSB1)+AT (ttyUSB2)+NMEA (ttyUSB2)+RMNET+ADB. Note it is possible to read the firmware content via ADB interface. ttyUSB1, ttyUSB2 and ttyUSB3 work the same way. You can submit AT commands to any port and get a response.

AT+GPSSTART does not work.
AT+GTGPSPOWER=1 activates the GPS.
AT+GTGPSPOWER=0 or AT+GPSEND deactivates the GPS.

I have no idea how to enable the output to NMEA port. But it is possible to request NMEA messages using the following commands:

AT+GTGPS="RMC"
AT+GTGPS="GGA"
AT+GTGPS="GSA"
AT+GTGPS="GSV"
AT+GTGPS="GST"

The response looks like

GTGPS:
$GPRMC,,V,,,,,,,,,,N*53


OK

Or AT+GTGPS? requests all messages at once

+GTGPS:
$GPRMC,,V,,,,,,,,,,N*53
$GPGGA,,,,,,0,,,,,,,,*66
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSV,4,1,16,02,,,26,04,,,28,07,,,28,08,,,29*7D
$GPGSV,4,2,16,09,,,28,10,,,27,11,,,27,12,,,29*72
$GPGSV,4,3,16,13,,,28,15,,,29,20,,,27,22,,,27*7C
$GPGSV,4,4,16,23,,,30,24,,,29,25,,,31,26,,,26*74


$PQGSV,1,1,02,01,,,28,02,,,31,0,5*63

OK

Note usually a modem sends a lot of messages to NMEA port. These messages may be almost the same for different types ($GPGSV for GPS, $GLGSV for Glonass, $GAGSV for Galileo, $PQGSV for Beidou). If the modem is well documented it is possible to enable only useful/supported messages and reduce a SPAM on the NMEA port and the CPU load.

I propose to implement on-demand mode. GPoint already has a timer to send the data to traccar or other server each few seconds.
It is possible to request only necessary data each few seconds.
To support Fibocom NL687-E it is enough to activate GPS by AT+GTGPSPOWER=1 and request AT+GTGPS="RMC" and AT+GTGPS="GGA" periodically.

Note the modem MeiGLink SLM828 has the following commands for such requests:

AT+GPSGNMEA="GGA"
AT+GPSGNMEA="RMC"
AT+GPSGNMEA="GSV"
AT+GPSGNMEA="GSA"
AT+GPSGNMEA="VTG"
AT+GPSGNMEA="GNS"

The response looks like

+GPSGNMEA:$GPRMC,215243.00,A,3203.6311,N,7671.4525,E,0.0,242.9,211025,10.2,E,A,V*7E


OK

There is also a simple request AT+GPSLOC=2 which returns almost $GPRMC:

+GPSLOC:215204.00,32.036311,N,76.714525,E,0.900000,129.992676,3,0.000000,0.000000,0.000000,211025,11

OK

or the following if coordinates are unavailable:

+GPSLOC:000000.00,-0.000000,S,-0.000000,W,0.000000,0.000000,0,0.000000,0.000000,0.000000,01010-3,0

OK

Note EOL may be very different. So I recommand to apply the patch from #38 to support any combinations of \r and \n.

On-demand mode can reduce the CPU load a lot.
It is simple because you need only 1 TTY port to send commands and get responses. And the port is not locked all the time.
What do you think?

[Kodo-kakaku]

I propose to implement on-demand mode. GPoint already has a timer to send the data to traccar or other server each few seconds.
It is possible to request only necessary data each few seconds.

Initially, the on-demand functionality was implemented in the first versions of gpoint, but this functionality was subsequently excluded due to a conflict with another project (modeminfo), and therefore we work only with the NMEA port.

On-demand mode can reduce the CPU load a lot.

Regarding the load: I have GPoint running alongside ModemInfo and other packages on a single-core MIPS and have not noticed any performance issues.

What do you think?

To implement this, I need a Fibocom NL687-E modem for research and testing before integrating it into the product.
I don't currently have one, but perhaps one of the project's supporters will be interested and support it.
Thank you!

[slydiman]

due to a conflict with another project (modeminfo)

Usually modeminfo uses ttyUSB1 and Smstools3 uses ttyUSB2. You can use ttyUSB2 on most modems if Smstools3 is not used.

In case of Fibocom NL687-E you can simply use ttyUSB3 for AT commands too w/o any conflicts.

BTW, Smstools3 does not work on Fibocom NL687-E (no idea why).

I think on-demand mode configuration my be hidden from UI and used only for certain modems.
Something like

    MEIGLINK = {
        START = {"AT+GPSCFG=\"outport\",1", "AT+GPSRUN=0,30,100,0,1"},
        STOP = {"AT+GPSSTOP"},
        ONDEMAND = {false}
    },
    FIBOCOM_NL687 = {
        START = {"AT+GTGPSPOWER=1"},
        STOP = {"AT+GTGPSPOWER=0"},
        ONDEMAND = {"AT+GTGPS=\"RMC\"", "AT+GTGPS=\"GGA\""}
    },

[Kodo-kakaku]

Maybe when I get some Fibocom modems, I'll think about implementing this functionality.
I couldn't get the NMEA port to work correctly once and decided to simply abandon that modem.
I don't think changing the operating logic just because of one vendor is a good idea.

[slydiman]

Maybe when I get some Fibocom modems

Note Fibocom NL687-E is QMI modem and uses Qualcomm chip which is very close to Quectel EP06-E and MeiGLink SLM828.
Most popular Fibocom L850-GL and L860-GL are based on Intel chip and they have absolutely different command set.