AT+CEREG? returns empty string && 1.20.2.rX "bricks" GPy

  • I recently had to go through a major rigmarole of of debugging, testind and eventually reflashing my GPy with a old firmware (1.20.2r2 --> 1.20.1) to recover from a scenario where the device would not boot (even with safe boot).

    Anyway, looking through the docs, I thought I'd try looking at the LTE configs that I have. Running the recommended print(lte.send_at_cmd('AT+CEREG?')) I get an empty line. You can see the output below:

    >>> print(lte.send_at_cmd('AT+CEREG?'))
    >>> lte.send_at_cmd('AT+CEREG?')

    This doesn't seem to be normal behaviour so wondering of this is a symptom of something?

    I will proceed to try to get the device firmware up to a more recent version, and see where that takes me.

  • @goldfishalpha Found a snippet somewhere about that and it is now a religious expectation to select both, it should just enable them by defult.

  • As per this topic, I should have erased the filesystem, and reset the CONFIG and NVS partitions during firmware reflashing. Doh!

    It is now working on 1.20.2.r6.

  • Right, I just updated the GPy from firmware 1.20.1 to 1.20.2.r0 and it's "bricked".
    Get the following when starting up VSCode (and Pymakr).

    AutoConnect enabled, ignoring 'address' setting (see Global Settings)
    Searching for PyCom boards on serial...
    Connecting to COM3...
    Connection error: Error: timeout
    Previous board is not available anymore
    > Failed to connect (Error: Port is not open). Click here to try again.
    Connecting to COM3...
    Connection error: Error: timeout

    And after pressing the reboot button:

    ets Jun  8 2016 00:22:57
    rst:0x1 (POWERON_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
    configsip: 0, SPIWP:0xee
    mode:DIO, clock div:1
    ho 0 tail 12 room 4
    entry 0x400a05bc

    Powercycling (unplug and plug in) gets me back to the first output.

    This is essentially the issue I started with a day ago but assumed it must have been something I did.
    So far, firmware version that I have tested and have failed, in ascending order, are:

    • 1.20.1.r2
    • 1.20.2.r0
    • 1.20.2.r2
    • 1.20.2.r6

    Essentially, so far I haven't found anything boot apart from 1.20.1. This has gotten very weird.

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