SIMCOM SIM7070G UART Support

[Alexey Orishko]

> I'm trying to configure a SIMCOM7070G modem to work with ModemManager/NetworkManager.
>
> I've observed there is already a plugin and some support, but unless I'm mistaken, it looks like the current support expects this modem to be connected via USB (4 ports provided by usb: AT cmds, data, gnss, etc).
Only AT cmd and data (2 ports) are needed as a minimum.

> My problem is I'm using it in a board where the modem is NOT connected to the CPU via USB: The regular UART (UART1) provided by the modem is used.
When you run PPP over UART1, it is not available for AT commands
(breaking data stream is not really an option).
You need another port for controlling a modem.

> Taking into account I want to establish a CAT-M, could somebody please help me with the configuration?
To configure a modem to connect to LTE Cat-M1 without GSM/Cat-NB use
AT+CNMP=38 and AT+CMNB=1

Alexey