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Thread: Teensy 3.5s stopped supporting USB connection

  1. #1
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    Teensy 3.5s stopped supporting USB connection

    Two of my Teensy 3.5s (S/N 474530 & 493475, both with PID 0486), after working for several hours, are suddenly no longer recognized by Windows 7/64 as providing a USB connection, so they can't be loaded with programs. Other Teensy 3.5s here, including two with the same PID, continue to be fine. What has happened? Also, what (if anything) can be tried to revive the two dead units?

  2. #2
    Senior Member+ defragster's Avatar
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    Do they respond to a Button push to program them? Can a simple Blink sketch with USB Serial active be uploaded?

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    Senior Member PaulStoffregen's Avatar
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    Every Teensy has a "Program" (not "reset") button so you can recover from any program which turns off USB or otherwise stops responding.

    For troubleshooting, bring the Teensy Loader window to the foreground and turn off Auto mode, which is on by default if you've used Arduino. Then press the Program button and watch the Teensy Loader window.

    Teensy Loader also has a Verbose Info window which gives a *lot* more info. It's hidden in the Help menu.

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    Thanks to @Paul & @defragster for your rapid responses.
    My problem is gone, but unexplained. I reattached the Teensys to Windows to follow @Paul & @defragster's suggestions, but I was pessimistic, since a few hours ago the Windows Device Manager couldn't detect that either of the culprit Teensys existed, and neither could Serial Port Monitor (https://helmpcb.com/software/serial-port-monitor), so the chance of loading theTeensys by any means seemed slim.
    Now, just plugging them in is all I need to do. They are recognized by Windows, and loadable by the default mechanism of the Arduino IDE. They of course accept Blink, and they equally well accept the 67KB program that I had been trying to load this afternoon.
    The only explanation I can think of is that there is a near-threshhold problem of signal strength between these Teensys and my PC's USB hardware, and a few hours of the latter's cooling off made a difference. I hate to rely on unconfirmable hardware speculations, but I can't think of what else might be going on.

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    Senior Member+ defragster's Avatar
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    Tough to say the reason - I had some go missing until I reprogrammed others it accepted - that was likely a long ago memory from Win 7. If something confuses or breaks Windows processing it seems to get put on an ignore list for some time - perhaps that is a real thing and these units triggered it.

  6. #6
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by Fenichel View Post
    My problem is gone, but unexplained.
    Kinda not so surprising with Windows 7. Microsoft fixed several USB bugs for Windows 10, but they never published those fixes as updates for 7, 8, or XP. Installing Windows 10 is the only way (other than Mac & Linux) to get fairly good USB drivers.

    Here's one of the really annoying Windows 7 bugs.



    This video was made after Phil T (of Adafruit) found the right person in Microsoft. They denied the bug existed. I made this video to prove it, and they finally admitted it was a bug. That was a few months before Windows 8. They never fixed it for Windows 8. They delayed a fix until Windows 10.

    Thankfully those bad old days of buggy Windows USB drivers are mostly behind us, except for the huge user base still on buggy Windows 7.

    I recommend upgrading to Windows 10, if you can. It really does work much better for USB.

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    problem explained and not fixed, but made tolerable

    The phenomena that made me start this thread seem to be similar to those shown in @Paul's video, so I suppose if they appear again, they will, after a while, go away again. For the moment, that's good enough for me.

    I know that many bugs have been fixed in the move from Windows 7 to Windows 10, but the last time I looked, Windows 10 was overly dependent on its cloud connections. It made me nervous. If Windows 7 becomes unbearable, that might be the time for me to move to Unix.

    Thanks again to @Paul & @defragster.

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