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Thread: New Tesnsy 4.0 not being detected

  1. #1
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    New Tesnsy 4.0 not being detected

    I just opened a brand new Teensy 4.0 and it is not detected when connected to the PC. It does power up and the red led does flash slowly, but the PC never sees it. Tried 2 different USB cables and tried pressing the program button and rebooting the PC.

    Anything else I should try before declaring it DOA?

  2. #2
    Senior Member+ KurtE's Avatar
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    Not sure what you mean when you say PC does not see it... Windows, MAC, Linux?

    Now assuming Windows, and you have a reasonably up to date system with Arduino installed and Teensyduino installed.

    What I will typically do, is to load up some simple sketch usually blink... And configure for Teensy 4, USB Type Serial...
    Then click on the verify button. After it completes the verify, the Teensy app should come up. Now if you press the program button on the Teensy, does the Teensy app see it and you see it programmed? And then a Serial port assigned to it?

    If Linux have you installed the udev rules?

    Good luck

  3. #3
    Senior Member PaulStoffregen's Avatar
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    I know you said you tried 2 different cables, but please understand we hear this over and over on this forum. It's almost always a charge-only cable. Sometimes we've had people discover as many as 5 cables they had left over from various products were all charge-only cables without data wires. They're incredibly common.

    If you have any other Micro B USB devices, make sure those cables really do communicate. Or get a 3rd cable which really does have data wires.

    There are 2 other things you can do without having a good USB cable. A brand new Teensy 4.0 should blink its orange LED (located near the pushbutton). When you press hold the button, the LED should stop, and when you release the button the red LED (located near the USB connector) should come on. This behavior can verify your Teensy 4.0 hardware is working.

    The other thing you can do is hold the button for 15 seconds. You'll see a quick flash of the red LED. If you release the button at that time, Teensy 4.0 will completely wipe its flash memory and restore the flash memory to a known-good copy of the LED blink program. You should see the red LED turn on bright for several seconds while it does this. When it finishes, the orange LED should return to blinking. Normally this should never be needed with a brand new Teensy 4.0, but it can be helpful if you ever manage to get "bad" code which confuses Windows USB driver loaded into the flash memory.

  4. #4
    Senior Member+ defragster's Avatar
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    Above notes are good and Paul assures each Teensy is verified to function before packaging.

    If that doesn't work the only other thing might be damage in shipping. Go over the Teensy with magnification compared to the card image - or the image on PJRC.COM - and verify that none of components have been knocked off top and bottom.

    Assuming no soldering done? If so that needs to be checked.

  5. #5
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    try another PC as well, in case your Windows has usb driver issues or hardware problem

  6. #6
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    Tried it on another computer and it worked. Brought it back to this one and now it works!

    No clue what happened.

  7. #7
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    Quote Originally Posted by KurtE View Post
    Not sure what you mean when you say PC does not see it... Windows, MAC, Linux?

    Now assuming Windows, and you have a reasonably up to date system with Arduino installed and Teensyduino installed.

    What I will typically do, is to load up some simple sketch usually blink... And configure for Teensy 4, USB Type Serial...
    Then click on the verify button. After it completes the verify, the Teensy app should come up. Now if you press the program button on the Teensy, does the Teensy app see it and you see it programmed? And then a Serial port assigned to it?

    If Linux have you installed the udev rules?

    Good luck
    My bad. I should have said Windows 10 PC.

    When I say the PC doesn't see it, I mean when you plug in a USB device you normally get a sound to conform it was detected and then if you look in the Device Manager you will see a Com port. When I first tried it on this PC, there was no sound and no com port.

    Final note: After seeing the suggestion on Charge Only Cables, I test the three I have and 2 of them indeed supply power but they do not allow the PC to recognized the Teensy. They must be Charge Only and the source of the problem. Those are headed for the trash.

  8. #8
    Senior Member PaulStoffregen's Avatar
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    Every brand new Teensy comes pre-programmed as RawHID, not Serial, so there should be no COM port until you've programmed it at least once (with Tools > USB Type set to Serial). We ship every Teensy this way because pre-10 versions of Windows lack the serial driver, but all versions have HID drivers - and on old versions of Windows HID is one of the few drivers Microsoft implemented well.

    Also, while in programming mode (like if you turn off Auto mode in Teensy Loader and then press the button on Teensy), the communication is HID, not Serial, so it is absolutely normal & correct behavior to see no COM port. Instead Teensy appears under Human Interface Devices, because it's using HID protocol in that mode.

    Likewise, if you set Tools > USB Type to any of the options which doesn't have Serial (like MIDI, Audio, Keyboard, etc) you will not have a COM port because it's running without Serial. But you can still use the serial monitor and Serial.print(), because we use a HID interface to emulate serial in those mode. Just remember, not everything is a COM port!

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