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Thread: Teensy 3.6 power-up issues

  1. #1
    Junior Member
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    Teensy 3.6 power-up issues

    Hi

    I want to power the Teensy 3.6 via Vin Pin through my Rigol DP832 with 5V, the trace to USB power is cut. If I connect the Teensy and turn the Power Supply output on, the Teensy does not start. If I remove the connecting wire between the Power Supply and the Teensy while the Power Supply output is on and reconnect, the Teensy does boot. It seems the Teensy needs a very sharp power up to boot.

    My test sketch:

    void setup()
    {
    pinMode(13, OUTPUT);
    }

    void loop()
    {
    digitalWrite(13, !digitalRead(13));
    delay(200);
    }

    What is going wrong? Any help appreciated.

  2. #2
    Senior Member+ MichaelMeissner's Avatar
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    Just to ask the obvious question. Besides connecting the 5v line to VIN, did you connect the ground line from your power supply to normal ground? Not the analog ground that is between the VIN and 3.3v pins, but the ground pin on the other side of the teensy (or the 3 other normal ground pins on the 3.6). Have you checked that your power supply is in fact delivering power?

    Also note, some USB batteries will turn themselves off if the unit does not consume enough power. A teensy often times consumes less power than these batteries meant to recharge cell phones are setup for. From looking at the Rigol on Amazon, I assume this is not the case, but I thought I would mention it.

  3. #3
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    I have connected the GND to all the GND Pins (analog and digital) they are all connected together, might that be a problem?
    The power supply is fine and the connections are sound.

  4. #4
    Senior Member+ Frank B's Avatar
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    Add a capacitor to the reset pin. Something like 100nF. Do some experiments with the exact value. Maybe 47nF or less works too.
    This issue is known - it's not a Teensy 3.6 -problem, it more a problem with "slow" supplys.

  5. #5
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    I tried that. Added all sorts of values 1n, 10n, 100n... unfortunately no luck.

  6. #6
    Senior Member+ Frank B's Avatar
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    Are you sure? Be sure to use the Reset PIN, not PROGRAM. It worked for others (and me).
    Ok, then just try an other supply - or add a reset-circuit that resets the teensy long enough until the supply is "ready".

  7. #7
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    I'm pretty sure I did. Beside the SD slot there are 5 pads. Soldered the capacitor between the middle pad (gnd) and the bottom one (RST) with the sd slot pointing to the left. On the bottem side of the Teensy they are marked with GND and R. Did I use the wrong location?

  8. #8
    Senior Member
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    Since you have a scope there, hook up a probe to your 5 volt supply and see how slow it ramps up. Maybe what you see on the scope will provide some insight to what you need to do.

  9. #9
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    Had a chance to scope the supply and the voltage ramps up from 0V to 4V in about 20ms (on the Rigol DP832).
    Click image for larger version. 

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    It seams that is to slow for the Teensy to start properly.

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