Arm Mbed OS support forum

Cellular connection fails

Hi there,

I’m working with Telit UL865 module which is connected to STM32F7-DISCO board to test the Cellular example. Somewhere in the initialization sequence, an unknown command is sent.

[3643ms][INFO][CELL]: AT TX (9): AT+CEREG?
[3648ms][INFO][CELL]: AT TX (1): <cr>
[3657ms][INFO][CELL]: AT RX (9): <cr><ln>ERROR<cr><ln>
[3659ms][WARN][CELL]: Get network registration failed (type 0)!
[3666ms][INFO][CELL]: AT TX (9): AT+CGREG?
[3671ms][INFO][CELL]: AT TX (1): <cr>
[3679ms][INFO][CELL]: AT RX (2): <cr><ln>
[3680ms][INFO][CELL]: AT RX (4): +CGR
[3685ms][INFO][CELL]: AT RX (15): EG: 2,3<cr><ln><cr><ln>OK<cr><ln>
[3692ms][INFO][CELL]: Network registration (timeout 180000 ms)
[3699ms][INFO][CELL]: Continue after 4 seconds

+CEREG command does not exist in the Telit AT command set documentation, instead it has +CREG command.

Is there any way of overriding this behavior? Am I selecting a wrong subset of AT commands from somewhere in the project? Or simply am I missing a configuration?

Thanks in advance

Hi, I only just saw this thread, so I am not sure if it will help (if you haven’t already found the solution.)

The cellular properties (an array with a lot of configuration items) are set up in the target modem’s Cellular Device constructor. You can selectively enable or disable each of CREG, CGREG and CEREG if appropriate.

I can’t see an implementation in mbed-os 5.15.1 (where our project has parked) for Telit UL865, but as an example, you could have a look in targets/Quectel/BG96/Quectel_BG96.cpp’s constructor for an example. The first 3 properties relate to these xREG queries.