Dragonfly nano becomes unresponsive after sleep mode

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  • February 12, 2020 at 4:04 pm #30269
    Daniel Smith
    Participant

    Hello, I have a Dragonfly nano (version without the mbed processor) hooked up to my own host processor. The application connects to the cellular network and can send data over a TCP port all day long just fine. I have implemented a sleep mode, where the host processor issues a +CPWROFF command, the modem shuts off, then the host processor goes to sleep.

    When the host processor wakes back up (triggered by motion detection), it starts up the modem like normal, and is able to start sending data again for about 16 seconds. Then, the modem suddenly becomes unresponsive. The RX serial line goes low, and it does not respond to any further AT commands. RADIO_LINK goes high (active low signal) and the LED indicator turns off, telling me that it has disconnected from the network. 1V8_MON, interestingly, stays high.

    I’ve tried holding NRESET for various amounts of time, like 500 ms or 1500 ms, but the only way to get the modem to respond is by removing power.

    This behavior is 100% consistent. It happens every time. So for now, I just don’t put the modem to sleep.

    Is this a bug or am I possibly doing something incorrectly? I can provide logic analyzer traces if that is helpful.

    February 12, 2020 at 5:32 pm #30271
    Leon Lindenfelser
    Moderator

    Hi Daniel,

    Please issue the following commands and let me know what the response is for each.
    AT+CPSMS?
    AT+UPSV?
    AT+UMNOPROF?

    Kind regards,
    Leon

    February 12, 2020 at 6:16 pm #30274
    Daniel Smith
    Participant

    Hello Leon, thanks for the quick reply. Here are the responses for those commands:

    AT+CPSMS?
    +CPSMS:0,,,”00011000″,”00001010″

    AT+UPSV?
    +UPSV: 0

    AT+UMNOPROF?
    +UMNOPROF: 0

    I confirmed that they are the same before and after the sleep events.

    February 13, 2020 at 9:00 am #30275
    Leon Lindenfelser
    Moderator

    Hi Daniel,

    I tried to duplicate the issue here with no luck. Please open a support ticket at https://support.multitech.com/support/login.html and put the above information in the case. That will make it easier for us to get everyone we need involved and figure out what’s going on.

    Leon

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