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Thread: More MINI54 Trouble

  1. #1

    More MINI54 Trouble

    After following all advice on board design for a custom Teensy board and using exactly the same parts
    used on the teensy, I have trouble getting my Custom Board running.

    If I press the PROG button, the Teensy Loader indeed uploads the code, but afterwards the code doesn't
    seem to run (LED Blink Example). I have verified the connections and everything seems to be fine.

    The only difference in my circuit is that I supply the 3.3V externally from a Bench Power Supply and
    that VBUS is not connected (which means only GND, D+, D- are connected).

    What I cannot explain: PROG seems to trigger firmware upload, but after code upload no USB device
    is being enumerated.

    Click image for larger version. 

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    Crystal is 8pF, Inductors are 10uH. VDD = 3.3V

    Crystal Symbol looks wrong on the Schematic, but all connections are good.
    The Capacitors and the Series Resistor is not assembled on the board.
    Last edited by syso2342; 02-26-2015 at 11:05 AM.

  2. #2

  3. #3
    Quote Originally Posted by PaulStoffregen View Post
    Looks like it could be it. Suddenly I got a weird effect: Both MK20 on 2 different boards assembled by 2 different people get suddenly
    hot whenever powered is applied. There are no shorts on the board and all solder points have been checked under the microscope.
    Did anyone have something like this before?

  4. #4
    Senior Member PaulStoffregen's Avatar
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    Just a couple days ago there was mysterious, still-unresolved heating of the chip on Teensy-LC when a certain OLED display was used.

    Amazing IR camera images were posted....

  5. #5
    Senior Member Constantin's Avatar
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    Don't discount the possibility of the OLED being at fault, in some strange way.

    I.e. the Teensy having to sink an inordinate amount of current, etc. that a UNO can tolerate more easily. I remember being rather amazed re: all the ways that a Uno can be fried by looking over the Ruggeduino specifications and discussion of their protection mechanisms.

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