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Thread: Teensy 3.2 custom hardware empty MKL02

  1. #1

    Teensy 3.2 custom hardware empty MKL02

    Hi,
    I am working with custom hardware that I designed using the Teensy 3.2 schematic with the MK20DX256VLH7 and the MKL02Z32VFG4 and I am thinking that the purchasing department accidentally placed empty MKL02 devices on the hardware.
    I am noticing that the RESET_B pin of the MK20 is being held low I believe due to empty MKL02. I also noticed that the 16MHz oscillator is not oscillating.
    Does anybody know if the oscillator stops oscillating when RESET_B is held low? Or is it more likely I am dealing with a bad oscillator setup?
    Thanks.
    Tim

  2. #2
    Senior Member+ Theremingenieur's Avatar
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    The MK20 starts always (if it starts) from an internal RC oscillator. The boot code will then enable the XTAL oscillator, the FLL/PLL, and the clock distribution module. So, yes, without a hex file loaded, it is normal that the XTAL oscillator does not yet work.

  3. #3
    Thank you so much for the confirmation. I was racking my brain trying to figure out why the oscillator wouldn't work.
    Do you happen to know if the USB connection would register anything in Hardware Manager if the MK20 does not have a HEX file loaded in the boot loader? I am not seeing any reaction on the computer when I plug into this setup and I would think it is also due to an empty MKL02.
    Thanks.
    Tim

  4. #4
    Senior Member+ Theremingenieur's Avatar
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    I confirm that without firmware (hex file) which would enable the USB hardware, a blank MK20 (be it blank because of an empty MKL02 or for any other reason) will not show up as a device in the device manager.
    Don‘t waste your time! There are two problems: First, you can‘t diagnose almost anything because of the blank MK20 and second, you can‘t load any firmware on it because of the empty MKL02. Fix the MKL02 problem first. Only then, you will see if the MK20 works correctly after you gave it some code to digest. A German proverb says „Ohne Heu zu fressen, kann das beste Pferd nicht furzen“ which translates to „without eating hay, even the best horse can not fart“

  5. #5
    Love it! Thanks...
    Tim

  6. #6
    Senior Member PaulStoffregen's Avatar
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    The easiest way to check if the MKL02 chip is programmed is looking at the voltage on the Program signal (pushbutton). If the code is present, you should see 3.3V because the code turns on the pullup resistor inside the chip. If the chip is blank, that signal will be floating. Usually you'll see a low voltage which fluctuates if you touch the wire.

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