/* Environmental data station build, using a ESP8266 NodeMCUV3, and the following sensors:
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DHT21(AM2301) for measuring indoor temperature (°C) & humidity (%RH).
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GY-21-Si7021 (I2C) for measuring outdoor temperature (°C) & humidity (%RH).
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CJMCU-811 CS811 (I2C) sensor measuring eCO2 (the equivalent CO2 400ppm to 8192ppm)& TVOC (Total Volatile Organic Compound 0ppb to 1187ppb). CCS811 receives temperature and humidity readings from BME280 for compensation algorithm. New CCS811 sensors requires at 48h-burn in. Once burned in a sensor requires 20 minutes of run in before readings are considered good. Connect nWAKE sensor pin directly to GND, so the CCS811 will avoid enter into SLEEP mode [sensor it's always ACTIVE]
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DS18B20 attached at a heating radiator metal tube for measuring the heating water temp, in order to register the heat cycles.
All data are transmited to a ThinkSpeak channel every 1 minute. Keep I2C sensor wires as sort as possible. Use high quality wires with as low capacitance as possible. Build by Konstantinos Deliopoulos @ Jan 2020. */