Teensy 4.0

Vendor: PJRC
Features: External Flash, USB
Source on GitHub: mimxrt/TEENSY40
More info: Website

Installation instructions

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

Instead of imxrt1062 with the --mcu option, you can as well use the board specific names TEENSY40, TEENSY41 or TEENSY_MICROMOD. When loading the firmware the PJRC boot loader will erase the board file system.

Note: If the Teensy board is equipped with Teensy bootloader v1.07 and up, the first attempt to upload the firmware may fail. In that case try again.

Firmware

Releases

v1.27.0 (2025-12-09) .uf2 / [.bin] / [.hex] / [Release notes] (latest)
v1.26.1 (2025-09-11) .uf2 / [.bin] / [.hex] / [Release notes]
v1.26.0 (2025-08-09) .uf2 / [.bin] / [.hex] / [Release notes]
v1.25.0 (2025-04-15) .uf2 / [.bin] / [.hex] / [Release notes]
v1.24.1 (2024-11-29) .hex / [.bin] / [Release notes]
v1.24.0 (2024-10-25) .hex / [.bin] / [Release notes]
v1.23.0 (2024-06-02) .hex / [.bin] / [Release notes]
v1.22.2 (2024-02-22) .hex / [.bin] / [Release notes]
v1.22.1 (2024-01-05) .hex / [.bin] / [Release notes]
v1.22.0 (2023-12-27) .hex / [.bin] / [Release notes]
v1.21.0 (2023-10-05) .hex / [.bin] / [Release notes]
v1.20.0 (2023-04-26) .hex / [.bin] / [Release notes]
v1.19.1 (2022-06-18) .hex / [.bin] / [Release notes]
v1.18 (2022-01-17) .hex / [.bin] / [Release notes]
v1.17 (2021-09-02) .hex / [Release notes]

Preview builds

These are automatic builds of the development branch for the next release.

v1.28.0-preview.18.g6341258207 (2025-12-19) .uf2 / [.bin] / [.hex]
v1.28.0-preview.4.gef567dc928 (2025-12-16) .uf2 / [.bin] / [.hex]
v1.27.0-preview.503.g2bd337ef18 (2025-12-08) .uf2 / [.bin] / [.hex]
v1.27.0-preview.491.g3f796b687b (2025-12-03) .uf2 / [.bin] / [.hex]