This is an Arduino library for TE Connectivity HTU20D/HTU21D, Sensirion SHT20/SHT21/SHT25, Silicone Labs Si7006/Si7013/Si7020/Si7021 Digital Humidity & Temperature Sensor

• HTU2xD +1.5v..+3.6v, SHT2x +2.1v..+3.6v, Si70xx +1.9v..+3.6v
• HTU2xD 0.14μA..0.500μA, SHT2x 0.04μA..0.330μA, Si70xx 0.6uA..180μA
• integrated resistive heater HTU2xD/SHT2x 1.83mA, Si70xx 3.1mA..94.2mA (4)
• temperature range HTU2xD/SHT2x -40°C..+125°C, Si702x (G-grade) -40°C..+80°C
• humidity range 0%..100% (1)
• typical accuracy T +-0.3°C at 14-bits, RH +-2% at 12-bits
• typical resolution T 0.01°C at 14-bits, RH 0.04% at 12-bits
• maximum T measurement time Si70xx 11msec, HTU2xD 50ms, HTU2xD 85ms
• maximum RH measurement time Si70xx 12msec, HTU2xD 16ms, HTU2xD 25ms
• I²C bus speed 100KHz..400KHz
• response time 8..30sec (2)
• recommended to route VDD or GND between I²C lines to reduce crosstalk between SCL & SDA
• power supply pins must be decoupled with 100nF capacitor

Supports all sensors features:

• read humidity (3)
• read temperature (3)
• soft reset
• enable/disable heater (4)
• set heater level, for Si70xx only
• set resolution
• read low voltage alarm
• read ID
• read FW
• CRC calculation (3)

Tested on:

• Arduino AVR
• Arduino ESP8266
• Arduino ESP32
• Arduino STM32

(1) Prolonged exposure for 60 hours at humidity > 80% can lead to a temporary drift of the signal +3%. Sensor slowly returns to the calibrated state at normal operating conditions.
(2) High frequency measurement causes the sensor to heat up, the interval must be greater than 0.5 second to keep self-heating below 0.10°C.
(3) Library returns 255 if a communication error occurs or CRC doesn't match.
(4) To remove dew from the sensor or to return the sensor to a calibrated state after prolonged exposure to humidity > 80%.