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Thread: Have I fried my board?

  1. #1
    Junior Member
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    Have I fried my board?

    Totally inexperienced noob here.

    I've been putting together a midi project with a TeensyLC. Initial plug in the board blinked. Then I did a bunch of soldering and a some desoldering and re-soldering. Now I try and upload the code I'm going to use and the board's led flashes briefly then doesn't come back on. I'm unable to upload anything to the board.

    I measured the voltage across 5v and 3.5v witih a multimeter and both are reading just under 1v. I checked it wasn't the multimeter by double checking an arduino uno I had kicking around and the voltage pins on that read as expected.

    Do you think I've fried the board, or is it likely there's some crappy soldering and trying to rework the connections may help?

  2. #2
    Senior Member+ defragster's Avatar
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    The LED doesn't flash for programming. If it flashes that is from running code - that may be running a short bit and taking the Teensy offline?

    Check your upload steps against those in this post and try that sketch and see what happens and provide details

    Opps - missed the voltage note ...
    Last edited by defragster; 04-29-2018 at 08:32 AM.

  3. #3
    Is there any way to flash bootloader for Teensy++ 2.0?
    Looks like I damaged it someway and before trow it away want to try recover the board.

  4. #4
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    @Kd - if your 5V is measuring 1V that will certainly prevent the Teensy starting. A resistance check 5V_> gnd with the plug out my be informative, along with looking for shorts. If that is all it is then possible to fix. What may have happened is that to much was drawn from the 3.3V supply. Which on the LC is generated by an on chip regulator and therefore cooking it will cook the main chip, and leave you with something that shorts the 5V supply and pulls it down. Without pulling the IC off the board hard to tell but certainly checking nothing is shorted across the 5V supply is useful

    @Momosh - there isn't an reasy way to recover the bootloader, though it should be also hard to break unless you got creative with hardware fuse settings. If you have a Uno handy you can try ICSP via the uno, but that will just make it a generic dev board rather than a Teensy.

  5. #5
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by momosh13 View Post
    Looks like I damaged it someway
    The only way to damage the bootloader is with an ISP programmer, or by physically destroying the hardware! You can't erase or alter the bootloader by uploading code from the USB cable, or by anything your program does. It's protected by a hardware lock mechanism. The only way to change the hardware lock is with an ISP programming, which requires connecting 4 signals including Reset.

  6. #6
    The AT90USB1286-MU is dammed, not the bootloader, I was planning to buy the processor for Digikey,

    https://www.digikey.com/product-deta...RCT-ND/2477090

    and replace it, and then load the bootloader, I have 5 Teensy++2 damaged.
    Wrong dc/dc 5v power supply killed them

  7. #7
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    will the costs and time be worth the time as opposed to just replacing them?

  8. #8
    Amazon $25

    https://www.amazon.com/PJRC-Teensy-2...teensy+%2B%2B2

    Digikey $8

    times x 5, I think yes

  9. #9
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    Well if you have time i guess its okay

  10. #10
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    Note the Teensy 2++ bootloader is not available, if you head down this path you will need to ICSP or use an open source AT90USB bootloader (and make configure Arduino to allow for the larger flash footprint).

  11. #11
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    Quote Originally Posted by GremlinWrangler View Post
    @Kd - if your 5V is measuring 1V that will certainly prevent the Teensy starting. A resistance check 5V_> gnd with the plug out my be informative, along with looking for shorts. If that is all it is then possible to fix. What may have happened is that to much was drawn from the 3.3V supply. Which on the LC is generated by an on chip regulator and therefore cooking it will cook the main chip, and leave you with something that shorts the 5V supply and pulls it down. Without pulling the IC off the board hard to tell but certainly checking nothing is shorted across the 5V supply is useful
    Thanks for the advice. Much appreciated. I de-soldered everything just now, and the board was back to OK, blinking and reading 5.x volts again. I learned a valuable lesson in applying test protocols. Tomorrow's a day off so I will try again, this time ensuring the board programs correctly before soldering anything, and testing functionality after every joint

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