Teensy is a complete USB-based microcontroller development system, in a very small footprint, capable of implementing many types of projects. All programming is done via the USB port. No special programmer is needed, only a standard USB cable and a PC or Macintosh with a USB port.

• Home (home page in the PlatformIO Registry)
• Documentation (advanced usage, packages, boards, frameworks, etc.)

1. Install PlatformIO
2. Create PlatformIO project and configure a platform option in platformio.ini file:

[env:stable]
platform = teensy
board = ...
...

[env:development]
platform = https://github.com/platformio/platform-teensy.git
board = ...
...

Please navigate to documentation.