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Adafruit_ADS1X15
Driver for TI's ADS1015: 12-bit Differential or Single-Ended ADC with PGA and Comparator
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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.
For analog input, probably something like this I²C ADC: https://www.adafruit.com/product/1083 which supports 4 digital channels. It connects to the SDA and SCL pins on the Arduino. You'll need this Arduino library to use it: https://github.com/adafruit/Adafruit_ADS1X15
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