Modem initialization fails

denisko3's picture


I am having difficulties with the 1st generation kit. Occasionally, it does connect to ATT LTE, but on most power-ups it does not. Looking at the output in cases when it fails I can identify two typical scenarios:
1) the modem initialization failure - infinitely repeating 0-60 count (Modem initializing... will take up to 60 seconds) and
2) infinitely failing registration [AT+CREG?+CREG: 2,0,0136,003AF009,7OK]

I understand that failure #2 is more difficult to fix because it depends not only on the kit but also on local towers, reception etc. although my cell phone report excellent reception and LTE. So I'd like to start troubleshooting with issue #1 - failure to initialize the modem. That should be something perfectly doable with software irrespective of external factors. Please advise.

Thank you!

jflynn129's picture

the situation you described is one of poor signal performance.  Because it will sometimes work and sometimes not work, I don't believe it to be a SW issue (the SW does the same thing everytime).  I would look at the antenna connections and signal strength that is being reported.  Be careful to look at your phone and say 'I've got good signal' because that just means you have good signal on your phone, not necessarily on the kit itself.  Try moving the kit to different locations and observe the behaviour for improvement.


The siguation where the modem times out and fails as you describe occurs when the modem is unable to establish a connection to the basestation (no Control Channel acquired).

tlagrone's picture

Similar to the above situation, I have both a LTE-M M14A2A module and the regular LTE module.  The LTE-M connection is very unreliable and the LTE connection is very reliable. Is there a difference in coverage for the different technologies?  Should software or APN be modified to support lower data rates? Did my test using the same SIM and K64F board and swapping WNC modules. Same situation for AWS and M2X connections (ATT sample programs).