BG96 - no communication

I am trying to communicate via UART with BG96 but it doesn’t react for any command.
The Status output is high, Net Status is “blinking”, the power supply is 3.78V but I can’t see anything on any UART interface.
USB port is connected to SoM module with Linux. In Linux I don’t see any device that corresponds to BG96.

My schematic:

And Termite conf:

Hi michalgaska,

Looks like you are using transistors to communicate over UART interface. We have same setup like you. Good idea. In that case, any TTL or logic convertors are not required to use.

So you need to check TTL voltage(1.8V, 3.3V?) of your linux board. Your COM port settings are true.

In Linux side, you can see usb events with type “dmesg” command to terminal. If you see anything to after plug into usb of your linux board, maybe Linux drivers for your modem not installed.

  1. Make sure your Vdd_ext load does not exceed 50mA.

  2. Is the Vdd_ext rating of 1.8V enough to turn on/off your BC847 transistors adequately?

  3. Make sure your level-translator circuits for the Tx / Rx are working okay.
    If possible, isolate the BG96 from these signals.
    Then, bridge the Tx / Rx circuits.
    Send an AT command and see if it echoes immediately.
    If not, you’ve found your first hurdle.
    (Don’t forget to unbridge the Tx / Rx and re-connect the BG96 to these signals.)