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Thread: Is Teensy 4.0 compatible with `hid_listen` ?

  1. #1
    Junior Member
    Join Date
    Jul 2021

    Is Teensy 4.0 compatible with `hid_listen` ?

    I have a brand new Teensy 4.0 board. Nothing else connected to it.

    I've attempted to get 'hid_listen' to work with this board, using the factory shipped "blink" firmware.
    Using 'hid_listen' on both Mac or Linux(with working udev rules) does not result in a connection, just "Waiting for device:....."

    The current documentation page has no mention of 4.0 support.
    That page only mentions compatibility with 2.0 boards (and 3.0 boards being supported by teensyduino).

    Contrastingly, I am able to use teensyduino's Serial Monitor using the code at
    and I am able to see "Hello World" being repeated.

    Is 'hid_listen' a tool I can use with my Teensy 4.0?


  2. #2
    Senior Member PaulStoffregen's Avatar
    Join Date
    Nov 2012
    Quote Originally Posted by buck View Post
    Is 'hid_listen' a tool I can use with my Teensy 4.0?
    No Teensy models past Teensy 2.0 and Teensy++ 2.0 work "out of the box" with hid_listen.

    In the very early days of Teensy, like 2008 to early 2009, development focused on use of command line tools like avr-gcc and hid_listen. By late 2009, the Arduino IDE became the primary way to use Teensy. By the time Teensy 3.0 launched in 2012, all development effort went into Arduino support. No code was ever published for newer boards to talk with the very old hid_listen program.

    But if you *really* wanted to use it, of course it is possible to dive into USB programming and make the newer boards use it. The protocol is pretty much the same as "seremu" which the non-Serial modes use to talk to the Arduino Serial Monitor. You could try editing the code on the Teensy side to use the same product ID number and other details as the very old Teensy 2.0 HID code. Or you could edit & recompile hid_listen to work with seremu.

    There's also 2 programs, teensy_gateway and teensy_serialmon, which Teensyduino installs into Arduino. Both do pretty much the same as hid_listen, though neither has much documentation (but you might find details on forum threads with good searching skills....) The teensy_gateway tries to automatically find Teensy boards and gives you no control over which one to use, much like hid_listen. The newer teensy_serialmon gives precise control over which hardware to use, with a special syntax that specifies the physical USB port, regardless of whether it is running seremu or regular serial. You could also try to use either of those programs.

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