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Thread: device not recognized, T3.5

  1. #1

    device not recognized, T3.5

    after many tests with a Teensy 3.5 uploading various code versions, now it is not possible to upload any code any more.

    USB type is serial. But I canot set the port as usual. Only COM1 is shown which definitely is not the Teensy port, see attachment.
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    The device is connected to and supported from USB.

    Have I killed the device?
    What can I do?

  2. #2
    Senior Member+ defragster's Avatar
    Join Date
    Feb 2015
    With T_3.5 unplugged from USB.
    Try a simple sketch in the IDE for T_3.5 and do a Verify Build.
    That will open the Teensy Loader.
    With the T_3.5 and cable in hand - press and hold the Button - Plug in the USB cable - pause - Release the Button on the T_3.5.

    Any response from the Teensy Loader program?
    Did it program?
    Does the IDE Port list now show anything?
    Teensy Loader has under Menu: Help / Verbose Info
    > Does that show anything? With a Button Press

    If nothing above - try another USB cable.

  3. #3
    no reactions at all.

    I guess I killed it. With the USB connected, all 3.3V outputs only show 0.5V. Except the USB cable there are no connections at all.
    A small black chip about 1cm from the controller chip in direction to the USB plug gets quite warm. Suppose it is the regulator from VUSB to 3.3V.

    I don't know what happened to kill the chip. For upload I used the TyTools integrated to the IDE. For some time it worked well. But since some days upload seems not to work correctly, because simple sketches behave abnormal, e.g. Serial.print() statements in a while(1) loop only once show an output then stops. But there is no code which could stop printing.

    Is it possible that some fuses are set in a wrong way?
    How could I check this?

  4. #4
    more info:
    During testing T_3.5 the connection between VUSB and Vin was cut and there was a 4.2V external power supply via Vin-pin.

    For such a configuration, is it necessary first to connect power to Vin and then plug USB or vice versa or does'nt the sequence matter?

  5. #5
    Senior Member+ defragster's Avatar
    Join Date
    Feb 2015
    AFAIK, Order VIN .vs. USB doesn't matter. But having the T_3.5 powered first will assure the Teensy is powered and ready when the USB is connected.

    Based on post #3 - and bad 0.5V on the 3.3V pins it seems there may be a hardware issue.

    TyTools isn't officially PJRC supported at all - but it is what is mostly used here for many years with no such issues.

    The Teensy Design and programming with Teensy Loader should never cause an issue with 'fuses set in a wrong way' or any user creatable problem from software uploads that would cause this. It may hang or fail to respond to USB with bad software, but the Button should always bring it back if there are no pin or device shorts or bad/abused components.

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