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Smoothieware
Modular, opensource, high performance G-code interpreter and CNC controller written in Object-Oriented C++
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InfluxDB
Power Real-Time Data Analytics at Scale. Get real-time insights from all types of time series data with InfluxDB. Ingest, query, and analyze billions of data points in real-time with unbounded cardinality.
There's a few forum threads around (eg this one regarding the Teensy arduino core), but I haven't seen any firmware stacks with the dynamic USB descriptor initialization and endpoint allocation you'd need for runtime custom USB function sets other than the one I wrote for Smoothie a decade ago.
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