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DxCore
Arduino core for AVR DA, DB, DD, EA and future DU-series parts - Microchip's latest and greatest AVRs. Library maintainers: Porting help and adviccee is available.
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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.
As I mentioned upthread, there is a very good Arduino core for the Dx chips. Even if you don't use it, the documentation alone is worth reading through: (https://github.com/SpenceKonde/DxCore). The same author also maintains cores for various ATTiny families.
NOTE:
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Hence, a higher number means a more popular project.