This is a version of ChibiOS for Arduino. I am starting a new repository since this version is not backward compatible with the previous libraries. Both AVR and ARM are now in a single library.
Teensy 4.0 has support for free running tick-less mode and periodic mode. The default for Teensy 4.0 is tick-less mode. Edit libraries/ChRt/src/teensy4/chconf_teensy4.h to select periodic mode or change parameters for Teensy 4.
See this article about ChibiOS tick-less mode:
http://www.chibios.org/dokuwiki/doku.php?id=chibios:articles:tickless
AVR also supports tick-less mode. The default is periodic mode. Edit libraries/ChRt/src/avr/chconf_avr.h to select tick-less mode.
Due, SAMD, and Teensy 3.x are supported in periodic mode.
The base code for ChRt was written by Giovanni Di Sirio, the author of ChibiOS/Nil and ChibiOS/RT.
See this site for detailed documentation of ChibiOS/RT.
http://www.chibios.org/dokuwiki/doku.php
The kernel is version 6.1.3 of ChibiOS/RT from ChibiOS release 20.3.3.
https://osdn.net/projects/chibios/releases
If you are installing from the GitHub repo zips, rename the folder ChRt before copying it to your Arduino/libraries folder.
Please read libraries/ChRt/doc/ChRt.html for more information. See the Examples section of the html documentation.
Start with the ChBlink example which is traditional for almost every RTOS.