There is a fairly recent standard published by ECSS that specifies the use of CAN bus and CANopen protocol for space applications (ECSS-E-ST-50-15C). It provides a reliable and fast bus that is feasible to be used in CubeSats, and makes a much better alternative to the commonly used I2C bus.
There are currently Micropython and C prototype implementation being developed under the LibreCube framework. For example, the Micropython implementation can be found here: https://gitlab.com/librecube/WP-1005.
Please feel free to provide your comments or feedback to this.
An example C implementation can be found here: https://gitlab.com/librecube/WP-1003
We will create a new work package to prepare a more generic C implementation for Atmel AVR 8bit microcontrollers, such that developers can use that as a template.
Is CANopen a proprietary standard? I thought I saw info elsewhere suggesting it wasn’t publicly available, but can’t find anything confirming that.
Note that we are revising the ECSS-CAN implementation into “SpaceCAN”. That one uses ECSS concept for redundancy management but does not include the bulky and complicated Object Dictionary. Instead, it uses the ISO-TP protocol for transfering larger messages between nodes.