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Thread: Can't power from VIN

  1. #1

    Can't power from VIN

    Hello, I'm new to the Teensy family. It's a fantastic device. Great job.

    I'm currently working on a project using the Teensy 3.2 that will eventually need to be poweed from VIN rather than having the USB connector plugged in. With the two pads on the bottom of the board bridged, the board runs as it should. With the trace cut between the pads, it worked once early on. I bridged the pads with solder again to do some out of circuit programming and testing. When I remove the solder bridge, I can't power the Teensy from the VIN pin. I'm using 5 volts to try and power the VIN when bridge is removed. The ground is connected to provide a common for the rest of the project regardless of whether the bridge is in place or not. If I re-bridge the pads, all works as it should. I've looked at things under a magnifier and I can't see that I've damaged anything. At this point I'm at a loss and looking for suggestions.

    Thanks in advance.

  2. #2
    Senior Member+ defragster's Avatar
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    Feb 2015
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    13,454
    Posted code may have answered this question - here is some speculation for this as it commonly happens.

    But in setup() or somewhere is there any code like : while ( !Serial );

    If so that will stop and wait for a connected cable and serial monitor on USB.

    If so replace it with something like: while ( !Serial && (millis() < 4000) );

    Another handy tool to show signs of life is in turning on the LED in setup:
    Code:
    void setup() {
      pinMode(LED_BUILTIN, OUTPUT); // Enable LED pin 13 output
      digitalWrite(LED_BUILTIN, HIGH);
      while(!Serial && millis() < 2000 ) {}
      }

  3. #3
    Quote Originally Posted by defragster View Post
    Posted code may have answered this question - here is some speculation for this as it commonly happens.

    But in setup() or somewhere is there any code like : while ( !Serial );

    If so that will stop and wait for a connected cable and serial monitor on USB.

    If so replace it with something like: while ( !Serial && (millis() < 4000) );

    Another handy tool to show signs of life is in turning on the LED in setup:
    Code:
    void setup() {
      pinMode(LED_BUILTIN, OUTPUT); // Enable LED pin 13 output
      digitalWrite(LED_BUILTIN, HIGH);
      while(!Serial && millis() < 2000 ) {}
      }
    Thanks! Your answer was spot on. I was already using the LED as an indicator that the board was running, which is how I know something wasn't right. I just took out that bit of code since it wasn't necessary for what I'm doing and all is well. I can run the board from the project power supply and still plug in the USB cable to work on programming when I need to.

    Thanks again for your help.

  4. #4
    Senior Member+ defragster's Avatar
    Join Date
    Feb 2015
    Posts
    13,454
    - glad you are back to enjoying your Teensy

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