Greybus
Introduction
Greybus is a lightweight, message-based protocol framework that provides a standardized way for hosts to access hardware functions implemented on remote modules. It was originally developed for modular systems and defines a set of well-specified operation protocols for common peripheral classes such as GPIO, I²C, SPI, PWM, and firmware updates.
The Greybus module for Zephyr provides an implementation of the Greybus protocol layers that map Greybus operations to Zephyr subsystems. When enabled, a Zephyr device can expose its hardware capabilities to a host using the Greybus protocols. The host discovers available functionality through Greybus manifest data, then issues class-specific requests that the Zephyr module processes and responds to.
Initially, Greybus was designed for use over Unipro [8]. However, the protocol itself is mostly independent of underlying transport. Currently, the Greybus module supports TCP socket as transport. However, any transport such as UART, I2C, etc should work fine. See the contents of this directory [9] for the current supported transport backends. Feel free to create PRs for new transport backends.
Greybus is licensed under a combination of Apache-2.0 and BSD-3-Clause license.
Usage with Zephyr
To pull in the Greybus for Zephyr as a Zephyr module, either add it as a West project in the
west.yaml file or pull it in by adding a submanifest (e.g. zephyr/submanifests/greybus.yaml)
file with the following content and run west update:
manifest:
projects:
- name: Greybus-Zephyr
path: modules/lib/greybus
revision: main
url: https://github.com/beagleboard/greybus-zephyr
For instructions regarding greybus subsystem usage, refer to the Greybus module repository [4] and Greybus samples [5].
All current development and real-world testing is done using BeaglePlay [6] and BeagleConnect Freedom [7].