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Thread: confused about Teensy Loader

  1. #1

    confused about Teensy Loader

    What does Press Button on Teensy to manually enter Program Mode mean ?
    When would I need to do that?


  2. #2
    Senior Member+ defragster's Avatar
    Join Date
    Feb 2015
    When a Teensy is connected to a computer and the Teensy is running the USB interface it generally/always responds to the TeensyLoader program indication from the computer and the button is not needed.

    If the Teensy is not loaded with a USB aware program or a program goes astray it may not be responsive to a computer program indication and then the Button has to be pushed.

    BTW: when a new Teensy leaves PJRC it ships with a NON USB aware Blink sketch loaded. So a NEW Teensy requires a Button press for programming until a USB aware sketch is loaded.

  3. #3
    Junior Member
    Join Date
    Apr 2020
    Teensy Button is IMHO one of the best features I've ever seen on a MCU board. If your code is voluminous the compiling can take a long time, and this can be a problem if you're testing something new: you check your code with "Verify" in Arduino, and when it checks out you have to press "Upload" and it compiles once again. With Teensy you just press the button to upload verified code, and it saves you one unnecessary step and a lot of time

  4. #4
    Senior Member PaulStoffregen's Avatar
    Join Date
    Nov 2012
    When you click Upload, the Arduino IDE compiles your program and tries to send it to your Teensy. Uploading can only happen automatically if your Teensy is running a previously loaded program which hears the USB communication. A tiny part of the code Arduino compiles into your program listens for a request to go into programming mode, so Teensy Loader can send the new program.

    If your code turns off USB, or goes into a deep sleep mode without USB wakeup, or leaves interrupts disabled, normal USB communication can't work. Without a way to manually get into programming mode, such programs could brick your board. The Program button on your Teensy is meant to give you a way to recover from putting those sorts of not-normal-USB programs onto your Teensy.

  5. #5
    I currently have the Blink program running on the Teensy LC.

    If want to upload Raw HID example sketch to the Teensy, do I have to do anything with the Teensy Button?

    I found that I have to select USB Type : Raw HID in the Arduino IDE; otherwise, I get 'RawHID' was not declared in the scope.
    Pressing the Teensy Button does not do anything.


  6. #6
    Senior Member+ KurtE's Avatar
    Join Date
    Jan 2014
    Did you change the USB type in the Tools menu to include RAW HID? If not, you will probably get these types of compiler errors

  7. #7
    I suppose I was confused by what if anything I needed to do with the Teensy Loader.
    And it appears that I should just leave it alone if I am using the Arduino IDE.

    With the Blink sketch, it looks like I can choose either USB Type: Serial or USB Type: Raw HID .

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