CODEWITHSUNDEEP
iotat-commandmodem
bas
bas

Reputation: 14912

Modem AT commands, unable to get into data mode (PPP)

I have a simcom7600 modem which I am trying out via AT commands.

I was able to use AT commands to setup the modem, and connect to an MQTT broker and exchange messages. Now I am trying to figure out how I can do something similar, but then with my own TCP/IP stack. Before diving into the deep there, I would like to confirm that I can get into data mode (PPP) which I am not able to, it seems.

I attached my modem (AT+CGATT=1), and activated it (AT+ACACT=1,1). I verified that I have a carrier/provider (AT+COPS?).

So I thought I was all set to send the ATO (online) commands. But it returns NO_CARRIER every time I try. I have no idea what I am doing wrong.

The logging that confirms above statements:

AT+COPS?
Sending command: AT+COPS?
AT+COPS?[CR][CR][LF]+COPS: 0,0,"NL KPN simyo",7[CR][LF][CR][LF]OK[CR][LF]
AT+cgatt?
Sending command: AT+cgatt?
AT+cgatt?[CR][CR][LF]+CGATT: 1[CR][LF][CR][LF]OK[CR][LF]
AT+cgact?
Sending command: AT+cgact?
AT+cgact?[CR][CR][LF]+CGACT: 1,1[CR][LF]+CGACT: 2,0[CR][LF]+CGACT: 3,0[CR][LF][CR][LF]OK[CR][LF]
ATO
Sending command: ATO
ATO[CR][CR][LF]NO CARRIER[CR][LF]

PS: the [CR][LF] stand for resp. \r and \n, I replace them before I log for ease of reading.

I obviously have to supply more info to the modem, but from this manual I can't seem to figure out which commands I miss, and how I could validate step by step that I am on the right track.

Upvotes: 1

Views: 3069

Answers (1)

bas
bas

Reputation: 14912

I found this nice document. I'll share it here in case somebody else struggles with this as well.

When I send the following commands:

  • ATZ (reset)
  • ATE0 (disable echo)
  • AT+CGREG? (check registration to PDP network)
  • AT+CGDCONT=1,"IP","internet" (set APN for my provider, they expect the string "internet")
  • ATD*99# (start data mode, aka PPP)

then I can break out and move back into PPP with the following commands:

  • +++ (send + character, wait for 700ms, send + character, wait for 700ms, send + character) => back to AT command mode
  • ATO (back to data mode)

NOTE: the APN your provider expects, is I think in all cases an easy Google. Your provider will most likely explain how to manually set your APN in case your phone won't do it automatically.

Upvotes: 2

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