TyTools is a collection of independent tools to manage, flash and communicate with Teensy microcontrollers.

Screenshot of TyCommander

Tool Type Description
TyCommander Qt GUI (static) Upload, monitor and communicate with multiple boards
TyUpdater Qt GUI (static) Simple firmware / sketch uploader
tycmd Command-line
No Qt !
Command-line tool to manage Teensy boards

Download the latest release from GitHub.

Using tycmd

You can manage multiple devices connected simultaneously, tycmd (and the other TyTools) uniquely identifies each device by its position in the host USB topology. Meaning if it stays on the same USB port, it is handled as the same device. That's necessary because across reboots and resets, Teensies look completely different to the host.

To target a specific device, use tycmd <command> --board "[<serial>][-<family>][@<location>]". serial is the USB serial number, family is the board family name and location can be the virtual path computed by tycmd (see tycmd list) or an OS device path (e.g. /dev/hidraw1 or COM1). Any of them can be omitted. See the examples in the table below.

Tag filter Effect
714230 Select board with serial number 714230
-Teensy Select board with family name 'Teensy'
@usb-1-2-2 Select board plugged in USB port 'usb-1-2-2'
@COM1 Select board linked to the OS-specific device 'COM1'
714230@usb-1-2-2 Select board plugged in 'usb-1-2-2' and with serial number is 714230

You can learn about the various commands using tycmd help. Get specific help for them using tycmd help <command>.

List devices

tycmd list lists plugged Teensy devices. Here is how it looks:

add 34130@usb-1-2 Teensy 3.1
add 29460@usb-4-2 Teensy
add 32250@usb-4-3 Teensy 3.0

Use --verbose if you want detailed information about available devices:

add 32250@usb-4-3 Teensy 3.0
  + capabilities:
    - upload
    - reset
  + interfaces:
    - HalfKay Bootloader: /dev/hidraw2

If you need to read structured information in your scripts, you can set the output to JSON with --output json:

{"action": "add", "tag": "714230@usb-6-3", "serial": 714230, "location": "usb-6-3", "model": "Teensy", "capabilities": ["reboot", "serial"], "interfaces": [["Seremu", "/dev/hidraw4"]]}
{"action": "add", "tag": "1126140@usb-6-2", "serial": 1126140, "location": "usb-6-2", "model": "Teensy LC", "capabilities": ["upload", "reset"], "interfaces": [["HalfKay Bootloader", "/dev/hidraw3"]]}

You can also watch device changes with --watch, both in plain and JSON mode.

Action Meaning
add This board was plugged in or was already there
change Something changed, maybe the board rebooted
miss This board is missing, either it was unplugged (remove) or it is changing mode
remove This board has been missing for some time, consider it removed

Upload firmware

Use tycmd upload <filename.hex> to upload a specific firmware to your device. It is checked for compatibility with your model before being uploaded.

By default, a reboot is triggered but you can use --wait to wait for the bootloader to show up, meaning tycmd will wait for you to press the button on your board.

Serial monitor

tycmd monitor opens a text connection with your Teensy. It is either done through the serial device (/dev/ttyACM*) or through the HID serial emulation (SEREMU) in other USB modes. tycmd uses the correct mode automatically.

You can use the --reconnect option to detect I/O errors (such as a reset, or after ab rerief unplugging) and reconnect immediately. Other errors will exit the program.

The --raw option will disable line-buffering/editing and immediately send everything you type in the terminal.

See tycmd help monitor for other options. Note that Teensy being a USB device, serial settings are ignored. They are provided in case your application uses them for specific purposes.

Reset and reboot

tycmd reset will restart your device. Since Teensy devices (at least the ARM ones) do not provide a way to trigger a reset, tycmd will instead start the bootloader first and then issue a reset without programming anything.

You can also use tycmd reset -b to start the bootloader. This is the same as pushing the button on your Teensy.

Hacking TyTools

Build on Windows

You can use MSVC (≥ 2015) or MinGW-w64. I have not tested Clang on Windows yet. The historical MinGW toolchain is not supported.

You need to install CMake to build the project files before you can use Visual Studio or MinGW.

If you don't have Qt, only the libraries and command-line tools will be compiled. There are two options to enable Qt in TyTools:

To build TyTools with MSVC 2015 32-bit, launch VS2015 x86 Native Tools Command Prompt, navigate to the project directory and execute CMake:

REM You can of course use another build directory if you prefer.
mkdir build
mkdir build/win32
cd build/win32
cmake ../..

This will create Visual Studio project and solution files in build/win32. You can then open the solution TyTools.sln.

To build 64-bit binaries, you should use VS2015 x64 Native Tools Command Prompt instead.

Build on macOS

Install Xcode, the developer command-line tools and CMake. The native Clang compiler can build TyTools.

If you don't have Qt, only the libraries and command-line tools will be compiled. There are two options to enable Qt in TyTools:

After Qt is ready, you can build TyTools by executing the following commands in the project directory:

# You can of course use another directory if you prefer.
mkdir -p build/darwin && cd build/darwin
cd build/darwin
cmake ../..

If you want to build debug binaries instead, you should specify the build type:

cmake -DCMAKE_BUILD_TYPE=Debug ../..

Build on Linux

TyTools can be built with GCC or Clang.


To install the dependencies on Debian or Ubuntu execute:

sudo apt-get install build-essential cmake libudev-dev qtbase5-dev

On Arch Linux you can do so (as root):

pacman -S --needed base-devel cmake udev qt5-base


Open the project directory in a terminal and execute:

# You can of course use another directory if you prefer.
mkdir -p build/linux && cd build/linux
cmake ../..

If you want to build debug binaries instead, you should specify the build type:

cmake -DCMAKE_BUILD_TYPE=Debug ../..


All the code related to these programs is under public domain, you can do whatever you want with it. See the LICENSE file or unlicense.org more more information.