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.
[env:stable]
platform = teensy
board = ...
...
[env:development]
platform = https://github.com/platformio/platform-teensy.git
board = ...
...
Please navigate to documentation.