micropython/ports/mimxrt/boards/deploy_teensy.md

For deploying the firmware use the Teensy Loader tool provided by PJRC on their web site. PJRC provides both a graphical and command line version for Windows, OS X and Linux. With the command line version, run the command:

teensy_loader_cli --mcu=imxrt1062 -v -w TEENSY40-<date_version_tag>.hex

or for Teensy 4.1:

teensy_loader_cli --mcu=imxrt1062 -v -w TEENSY41-<date_version_tag>.hex

When loading the firmware the PJRC boot loader will erase the content of the board file system.