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Thread: Teensy 3.5 Flash without bootloader?

  1. #1
    Junior Member
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    Teensy 3.5 Flash without bootloader?

    Hi,

    I have a problem with the teensy 3.5 bootloader which seems to stop working.

    I have made some changes in my program and flashed the teensy as normal. I am not sure but I think I add to much voltage to a analog pin, which is externally protected against higher voltage than 3.3V. Also the lcd stops working. After disconnect and reconnect everything looks like working normal even also the analog input. Only the bootloader seems to be corrupted.

    Now my question: Is it possible to flash the Controller without the bootloader? I have an Atmel ICE on Hand.

    As the teensy is brand new (few days) I dont want to loose it ☹️

    Thanks,
    Jens

  2. #2
    Senior Member+ Theremingenieur's Avatar
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    The Teensy is not an Arduino which has a boot loader program in its flash memory.
    The Teensy’s flash memory is 100% dedicated user program space. Uploading is handled via a separate processor on your Teensy board, a MKL02 or MKL04 IC which takes commands over USB and puts the Teensy’s main processor into programming mode before the Teensy loader software’s data stream is routed and written to the flash memory.
    So, it’s normally impossible to destroy the boot loader because there isn’t one in the Arduino sense and the “programmer” is on board.
    What can happen is broken communication between the main processor and the MKL0X because of an unresponsive main processor. The PJRC website gives detailed instructions for that case: https://www.pjrc.com/teensy/troubleshoot.html
    What you should learn from that is that one should never buy a single Teensy when you do serious or commercial development. “Ooooops” situations and magic smoke happen accidentally to the most experienced people. That’s why one should always have a second or third Teensy in the drawer. This allows differential diagnosing, too, in situations where you aren’t sure if it’s a hardware or a software issue.

  3. #3
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    Hi Theremingenieur,

    thanks for your reply. Ok I will Check if the communication is broken or not and search the faq.
    I have a couple of teensys, replacing is not a problem but I would like to find the root cause (I am electronic engineer).

    BR,
    Jens

  4. #4
    Senior Member+ Frank B's Avatar
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    Have you tried to press the button? It's not a "reset"-button - it starts the bootloader.

  5. #5
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    Thanks Frank, yes I had .... with a new Teensy everything works well.

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