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Thread: Teensy 2.0 stopped working (no blink on connect)

  1. #1
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    Teensy 2.0 stopped working (no blink on connect)

    Hi,

    I have a Teensy 2.0 board and it stopped working. When I first connected it to the host (Windows XP Pro 32-bit SP2) the LED started blinking and everything seemed to be OK. Then I started the Teensy loader and pressed the reset button. I got the error 'Power surge on USB port' and nothing happend. I tried to use an USB HUB with an independent power supply but the problem persisted.

    I solved the power problem by using an USB cable intended for an external USB HD. It has two USB connectors (to the PC) for additional power for large drives. After connecting the board the LED blinked normally. However, when I started the loader and pressed the reset button the LED stopped blinking but the loader did not recognize the device (it kept on telling me to press the reset button). I tried it a few times w/o success. After the last trial something happened to the board. When I connect now (using the same PC and cable) the LED does not blink and nothing happens when I push the reset button.

    I have searched this forum and tried Google with different search terms but I was unable to find an answer to my problem. I have tried the only suggestion I could find, i.e. restarted the PC, fired up the loader and connected the board while pressing down the reset button. This did not help either, the loader still said to press reset and the 'Operations->program' menu item was grayed out.

    I would appreciate getting some suggestions about how to make my board work again or how to determine if it is bricked.

    Thanks!

  2. #2
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    Sounds like something is shorting.

    Is your teensy connected to any external circuitry? Check the soldering of your pins.

  3. #3
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    Quote Originally Posted by Cosford View Post
    Sounds like something is shorting.

    Is your teensy connected to any external circuitry? Check the soldering of your pins.
    Hi,

    Thanks for the tip! The board was indeed inside the final circuit. After I removed it and connected to the PC it was recognized and the loader is ready for programming. I will have to check the external circuit. However, it worked (at least started up and blinked the LED) for a few times inside the same circuit which is a finished PCB board, not a breadboard with loose wiring. Strange. It will be a PITA if I have to remove it every time when I want to reprogram it.

    Q: Is there a zero-insertion-force socket for the Teensy 2?

  4. #4
    Senior Member PaulStoffregen's Avatar
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    Sounds like it was working at first. The LED is supposed to blink when you plug the board into the USB power, and it's supposed to stop blinking when you press the button. At least that _was_ a good sign, before something went wrong.

    If the board isn't blinking when you plug it in, there's pretty much 3 possible causes: #1 - it might not be getting power, or #2 - maybe it did get reprogrammed during a previous trial, with code that doesn't blink, or #3 - it's dead.

    #1 is fairly easy to check with a voltmeter. Just check if there's 5V between VCC and GND.

    #2 is harder to check. You'll need a known-good USB cable, and a known-good USB port on a PC. Hopefully you can find some other USB device with the same connector, to make sure you have a working cable that can allow communication. With a good cable, hold the button down while you plug in the Teensy, and release the button after the cable is full mated. Holding the button prevents any previously-loaded code from interfering. When you release the button, if the Teensy, cable and USB port are all good, Teensy Loader will detect the board.

    If the board is getting good power but doesn't respond for #2, then unfortunately it's dead.

  5. #5
    Senior Member PaulStoffregen's Avatar
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    Ah, I see you posted while I was typing. Your first message didn't mention you were testing with the Teensy soldering into a project and other stuff connected. Kind of an important detail to omit.....

  6. #6
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    If it's not reprogramming in-circuit; then it is far more likely there is an issue with your PCB than with the Teensy.

    A few things to check;

    How are you powering the board?
    Are you using the onboard regulator (on the teensy) or an external one? Remember, you should not be powering the teensy from USB and externally at the same time. If you are using the onboard, have you checked your current draw from the regulator?
    Have you checked your board for shorts or otherwise very low resistance paths between Vcc and Ground? (You can see if this is the case by using an ammeter to measure current draw of the entire board from whatever you're using to power it)
    Last edited by Cosford; 01-06-2015 at 12:40 PM.

  7. #7
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    Sorry, you are right, I should have mentioned that it was in-circuit. I will be more careful next time.

  8. #8
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    Hi,

    The problem is solved. I have istalled two jumpers on my board to completely disconnect the Teensy from the +5 V supply and the ground and now it works in-circuit as well. It seems that the passive components in my circuit board (probably the buffer capacitor of the power supply and the decoupling ones at the power pins of the ICs) interfered. I have also removed all the other ICs from their sockets (probably unnecessary).

  9. #9
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    Quote Originally Posted by PaulStoffregen View Post
    Sounds like it was working at first. The LED is supposed to blink when you plug the board into the USB power, and it's supposed to stop blinking when you press the button. At least that _was_ a good sign, before something went wrong.

    If the board isn't blinking when you plug it in, there's pretty much 3 possible causes: #1 - it might not be getting power, or #2 - maybe it did get reprogrammed during a previous trial, with code that doesn't blink, or #3 - it's dead.

    #1 is fairly easy to check with a voltmeter. Just check if there's 5V between VCC and GND.

    #2 is harder to check. You'll need a known-good USB cable, and a known-good USB port on a PC. Hopefully you can find some other USB device with the same connector, to make sure you have a working cable that can allow communication. With a good cable, hold the button down while you plug in the Teensy, and release the button after the cable is full mated. Holding the button prevents any previously-loaded code from interfering. When you release the button, if the Teensy, cable and USB port are all good, Teensy Loader will detect the board.

    If the board is getting good power but doesn't respond for #2, then unfortunately it's dead.
    I know that this post is really old, but according to this guide, my board must be dead. Any idea why it is so, and how I can avoid the same problem in the future?

  10. #10
    Senior Member+ manitou's Avatar
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    Quote Originally Posted by NadRad View Post
    I know that this post is really old, but according to this guide, my board must be dead. Any idea why it is so, and how I can avoid the same problem in the future?
    Did you buy your Teensy 2 from PJRC or an approved Teensy distributor? Often counterfeits are unreliable.

    https://forum.pjrc.com/threads/23601...l-Distributors

  11. #11
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    Quote Originally Posted by manitou View Post
    Did you buy your Teensy 2 from PJRC or an approved Teensy distributor? Often counterfeits are unreliable.

    https://forum.pjrc.com/threads/23601...l-Distributors
    I've bought it from a local store (opencircuit.be).

    I didn't know about counterfiets before reading the forum yesterday. The only thing I can say is that the LED is orange!

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