2
\$\begingroup\$

I recently got a SIM7600G breakout board and wanted to use it with the CGPS functionality for A-GPS. It works with connecting with my SIM to the Internet and all, but when I try to use AT+CGPS=1,3 (UE-assisted mode), I receive the following in response to my setup:

OK
+CGPS: 0

I interpret this as the GPS being turned off in response to this mode being selected.

I am currently interacting with the board via USB and with the "AT Command Tester For Simcom Modules", so I don't think it's a voltage issue as the other final post indicated. My current setup is as follows, all "OK" in response and no errors:

AT+CGSOCKCONT=1,"IP","APN_HERE"
AT+CGPSURL="supl.google.com:7276"
AT+CGPSSSL=0
AT+CGPS=?
AT+CGPS?
AT+CGPS=0
AT+CGPS=1,3

While mode 2 does work (UE-based), this is extremely inaccurate and defeats the purpose of my project. Has anyone ever gotten UE-assisted (A-GPS) mode to work on the SIM7600, let alone any Simcom module? If so, how did you get it to work? Is it a SUPL server issue? Firmware?

Any help would be greatly appreciated!

\$\endgroup\$
13
  • \$\begingroup\$ Just a quick comment. (1) As you said, your test setup, including Mode 2, are all OK except coming to Mode 3 (AT+CGPS=1,3), my first wild guess is that it is not USB/UART problem, because it is all simple serial UART interface, at which level only the level at AT commands are interpreted. (2) If I was doing troubleshooting, I would try the following: (a) Use Windows 7/10 USB to serial adaptor cable, and not Widnows USB to SIM7600 USB, because SIM firmware might not entertain all USB to SUB stuff, / to continue, ... \$\endgroup\$
    – tlfong01
    Dec 20, 2021 at 3:19
  • \$\begingroup\$ (b) If you are using Rpi python, you might like to compare and contrast my basic SIM7600 test program with sample outputs: (3) Reference: Rpi3B+ Python ... SIM7600 Problem, Asked 1 year, 5 months ago, Viewed 642 times: raspberrypi.stackexchange.com/questions/113992/…. \$\endgroup\$
    – tlfong01
    Dec 20, 2021 at 3:19
  • \$\begingroup\$ (3) Ah, you remind me one thing: I played with Neo-6/7/8 GPS Modules before trying SIM7600 GPS. When I first tried SIM7600 GPS, my first feeling was that its GPS hardware is a bit outdated, comparing to Neo. So I decided to switch back to Neo, with their very user friendly Windows based GUI interface. (4) References: Rpi Neo-6M / Neo-8M GPS Module Setup / Fix / Update Problems (a) electronics.stackexchange.com/questions/557417/… / to continue, ... \$\endgroup\$
    – tlfong01
    Dec 20, 2021 at 3:39
  • 1
    \$\begingroup\$ @tlfong01 Thank you very much for your replies! I don't think it's necessarily a USB/serial communication issue (but tell me if I'm wrong), as all other GPS modes (1 and 2) both work via USB with the "AT Command Tester for Simcom Modules" app, as well as via UART with my Arduino and the serial interface. Given that I am able to relatively quickly obtain GPS coordinates with mode 1 (AT+CGPS=1,1), I imagine that my standalone GPS portion is alright, would you agree? As for autobaud, I made sure that it has been fixed on 115200 in both environments that I tested. \$\endgroup\$
    – user1995565
    Dec 20, 2021 at 13:25
  • 1
    \$\begingroup\$ @tlfong01 What other possibilities do you think I should consider as to why only mode 3 returns 0, indicating that the GPS is now turned off? Please let me know if I misunderstood any advice you gave me. Thanks in advance! \$\endgroup\$
    – user1995565
    Dec 20, 2021 at 13:26

1 Answer 1

Reset to default
0
\$\begingroup\$

I was using mode 1 and was getting GPS position that was off by about 30 miles. Got the solution directly from Waveshare: the decimal minutes need to be divided by 6. Once I know about that transformation, I could put the new coordinates into Google Maps and got an accurate location.

So, a Lat from the AT command of 3248.514943,N needs to go through: 3248.514943 ==> 48514943/6 ==> 80858238 ==> 32.80858238

Do the same with the Long and you get an accurate position in Mode 1.

You can get out your Google Translate and see https://blog.csdn.net/qq_43231904/article/details/121402804?spm=1001.2014.3001.5501

\$\endgroup\$
2
  • \$\begingroup\$ Hey @terrydba, thanks for the reply! So mode 1 is for local GPS module only. I didn't have issues with that for my SIM7600 for for mode 2 being wildly inaccurate, and mode 3 simply not working. Would you say that your solution applies to the assisted GPS for mode 2, UE-based? \$\endgroup\$
    – user1995565
    Jan 13, 2022 at 17:07
  • \$\begingroup\$ That's a weird way to convert from minutes to degree-fractions. It relies on the exact number of digits behind the decimal point. Instead, I'd do (in Python) deg = val // 100; min = val - deg * 100 (so min is now 48.514943); full_deg = deg + min / 60, which also results in 32.80858238. But how would your method work with a value like 3200.00123? \$\endgroup\$
    – glglgl
    Sep 23, 2022 at 9:21

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.