Nb-IoT problems

  • I am trying to migrate an existing project on fipy and NB-IoT. This is a Low Power project and the first issue is that the modem does 30 seconds on average to attach, which means a 200mA current dissipation during the process, so Low Power is out of question.

    Another issue I had is that suddenly a fipy stopped working. It was sending non stop for a few days and one day suddenly it was unable to send. After some testing I figured out that it transmitted data only after disconnecting power and reconnecting it, so it sent data on the first run after connecting power and then it failed to attach every other run. Reset didn't make it work ,only removing power supply and reconnecting it.

    After that I did all the firmware updates for fipy core and modem. Modem was unable to accept firmware updates and failed entering recovery mode. Eventually I did the firmware updates on another fipy which worked alright with same code. That is the error it threw.

    Entering recovery mode
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
      File "/flash/lib/sqnsupgrade.py", line 126, in run
    OSError: AT+SMSWBOOT=3,0 failed!

  • @nalexopo this was my mistake apparently due to not initializing lora in sleep mode. I think pycom should disable automatically via firmware radios on boot and let us enable whichever we want to use.

  • Also even though I succesfully deinit LTE sometimes it enters deepsleep with 25uA but other times randomly stalls at 62mA.

  • Regarding long attach process - according to my understanding when eDRX and PSM features will be available it should be necessary to perform attach and connect only after first boot. During following wake-ups from deep-sleep it should be possible to transmit immediately.
    Those features should be implemented according to Pycom however I did not get any timeline.

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