GPS engine start-up in A-GPS mode not working. | Telit Cinterion IoT Developer Community
April 12, 2019 - 4:42am, 1638 views
Hi,
We're currently upgrading our PHS8 based tracking product to LTE using the PLS8. The device's main microcontroller has limited RAM and to save on temporary storage, we used a "trick" with the PHS8 to avoid having to buffer an A-GPS file that's being downloaded. We're using the UART interface and the CMUX multiplexer. To save an A-GPS file to the modem's internal file system we initiate a download on one of the multiplexer's IP channels and then use AT^SBNW to immediately turn that data around as it arrives, back into the multiplexer where it gets sent over the command channel to be stored in the modem's file system. Unfortunately, that strategy doesn't seem to work with the PLS8. In the case of the PLS8, the process appears to work properly. The modem responds with, "CONNECT AGPS READY: SEND FILE ..." at the beginning of the transfer and, "AGPS END OK" when the transfer is done. However, when we try to inject the A-GPS data saved in the modem into the GPS engine, we get one of two responses: "AGPS: INTERNAL ERROR", when downloading an "xtra.bin", GPS only file, or "A-GPS not updated!", when trying with an "xtra2.bin", GPS + GLONASS file. Even though there is no CRC error with the file and it seems to download ok, could you please let me know if it might be getting corrupted in the modem trying to store it this way, or if there might be some other explanation for the errors when trying to start the GPS engine in A-GPS mode?
Thank you,
Ed Haslam
Integrated Tracking Technologies Inc.
Hello,
Could you paste a log with all AT commands and replies and GPS configuration? Please add ATI1 and AT^SGPSC="Info","Xtra" replies too.
I have tried this with my PLS8 module and there were no errors.
Please note that according to documentation for PLS8 module you can only load xtra2.bin file.
Please make sure that you have set the correct UTC time on the module, GPS engine is stopped and the old file is deleted before you try to load the new one.
Best regards,
Bartłomiej
Hi Bartłomiej,
Thanks very much for your reply. AT commands and responses being tried for A-GPS operation are as follows:
^SYSSTART
ATE0
OK
AT+CGSN
35711308000158
OK
AT^SGPSC="Power/Antenna","off"
OK
AT+CMEE=2
OK
AT\Q3
OK
AT^SIND=simstatus,1
^SIND: simstatus,1,5
OK
AT^SIND=nitz,1
^SIND: nitz,1,"19/04/18,23:48:42",-28,1
OK
AT+CNMI=2,1,0,0,1
OK
AT+CIMI
3027205038232xx
OK
AT^SCID
^SCID: 8930272040305828xxxx
OK
AT+CMGF=1.
OK
AT+CPMS="ME","ME","MT"
OK
AT+CGDCONT=1,"IP","internet.com"
OK
AT+CGDCONT=2,"IP","internet.com"
OK
AT^SIND=service,2
^SIND: service,0,1
OK
AT+CMUX=0.
OK
AT+COPS?.
+COPS: 0,0,"ROGERS",2
OK
AT^SGAUTH=1,0
OK
AT^SICA=1,1.
OK
AT+CGPADDR=1
+CGPADDR: 1,"25.xx.30.79"
OK
AT^SISS=2,"srvType","Socket"
OK
AT^SISS=2,"address","socktcp://xtra2.gpsonextra.net:80".
OK
AT^SISS=2,"conId",1
OK
AT^SISO=2
OK
AT^SIST=2,5,1
+CME ERROR: operation temporary not allowed
AT^SIST=2,5,1
+CME ERROR: operation temporary not allowed
AT^SIST=2,5,1
OK
AT+CCLK="19/04/18,23:42:57"
OK
AT^SGPSC="Engine","0"
^SGPSC: "Engine","0"
OK
AT^SBNW=agps,57791
CONNECT
AGPS READY: SEND FILE
AGPS: END OK
AT^SIST=2,5,0
OK
AT^SISC=2
OK
A-GPS Not Updated!
AT^SGPSC="Engine","1"
^SGPSC: "Engine","1"
OK
AT^SGPSC="Nmea/Output","on"
^SGPSC: "Nmea/Output","on"
OK
The above may look a little odd because it's an edited version of the detailed debug file that the firmware in our device generates. We're using the cmux multiplexer with a uart connection and unfortunately, I don't have direct access to the UART pins on the modem. This command sequence did work with PHS8 modems but hasn't worked for us with the PLS8 so far. Response to the AT^SGPSC="Info","Xtra" command is: ^SGPSC: "Info","Xtra","0","0","0"
Thank you,
Ed
Hello,
The application seem to still be downloading the file while it is being uploaded as AGPS data - that's probably your solution to save memory described at the beginning. On the other hand SBNW command replies with "AGPS: END OK" and not with any of the error messages, so it seems that the file was successfully uploaded. In that context I'd expect some other reply from AT^SGPSC="Info","Xtra" than ^SGPSC: "Info","Xtra","0","0","0" which indicates no valid data.
Do you have a possibility to test it manually? And please also try to delete the old data with AT^SBNW=agps,-1 before.
Regards,
Bartłomiej