After a while of hacking at this periodically using the Raspberry Pi SDK, I was able to get the Drive To Position command to run consistently on an Adafruit Metro M4 board running CircuitPython. The functionality of this command to drive to waypoints on the floor is why I bought two RVRs during the Kickstarter in April 2019.
Here’s a YouTube video overview: https://www.youtube.com/watch?v=_pQCuEeRqjE
I also made a PDF of my notes with links to different relevant parts of the SDK linked here. This includes the files that have the commands for each subsystem, though @rmerriam has already done a fantastic job of documenting these all in one place.
The Raspberry Pi has always seemed like overkill for the RVR since serial commands don’t take that much processing power. Given that the microbit and Arduino SDKs haven’t been updated in over a year, I took time to understand the Python SDK and build the functionality myself. I was successfully able to hack the SDK to work with the full Message protocol, but I don’t think the license permits me to release that code
My hope is that we might work together to build an open RVR python library for microcontrollers that sends the full list of commands without the overhead of the full Raspberry Pi SDK.
I hope you can learn from what I’ve done. Let me know if you have questions!