David Sun

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  • April 2, 2019 at 1:34 pm in reply to: Use AT commands over UART on mDot #27591
    David Sun
    Participant

    Hi Leon,

    VDD is 5V, which I confirmed to be the case on the scope.

    It is indeed a direct connection to UART.

    Also, I used another mDot in the meantime with the same microcontroller and connections, which sent back the “OK” correctly.

    So I’m convinced this is definitely an issue with this particular mDot.

    April 1, 2019 at 5:10 pm in reply to: Use AT commands over UART on mDot #27582
    David Sun
    Participant

    Hi Leon,

    So I reset it and checked under an oscilloscope again.

    It seems that I am getting a response, but it is a very low voltage: not high enough for my main microcontroller to identify as a UART signal.

    Any ideas on why that might be? I am just sending “AT” to see “OK” from the Mdot. See picture attached.

    oscilloscope output from Mdot

    April 1, 2019 at 1:29 pm in reply to: Use AT commands over UART on mDot #27579
    David Sun
    Participant

    Hi Leon,

    Yes, my baud is 115k and I connected ground. I can verify that it is not an issue with UART on my main microcontroller, as I can communicate with a different microcontroller just fine over UART using the same baud.

    So I recently looked under an oscilloscope on the Tx pin of the Mdot and there wasn’t anything coming out, despite it being powered on and receiving a UART signal from my main one.

    Maybe I have to reflash the firmware?

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