Read signal level for ppp connection on RasPI

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I have a RasPI 3 with SIM800L connected via UART.

I use PPP connection to enable network traffic, and I want to get the signal level via AT command but device is busy when PPP is on.

Is it possibile to access to signal level? Or send a AT commands?

at-command raspberry-pi3
1 Answers

You can suspend your PPP call using +++ escape sequence. Something you need to know about the escape sequence:

  1. It doesn't end the PPP connection; it just makes you control again AT UART while in the background it is mantained active
  2. Before sending it, you must avoid sending characters for 1 second
  3. The +++ string needs to be sent with no further character in the middle within 1 second
  4. After sending it, you must avoid sending characters for 1 second. Only then it will be interpreted as escape sequence (this is to avoid +++ to be misinterpreted as data)

After you receive the OK response, you have AT interface back and you can send AT commands without dropping PPP connection, for example your AT+CSQ command to query signal quality.
Of course it is better to avoid to stay too much in suspension, in order to avoid inactivity timeouts from the remote peer.

After you're done with the commands, you can restore data mode with ATOcommand.

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