Description¶

The SHT21 and SHT25 are humidity and temperature sensors in a DFN package ofonly 3 x 3 mm footprint and 1.1 mm height. The difference between the twodevices is the higher level of precision of the SHT25 (1.8% relative humidity,0.2 degree Celsius) compared with the SHT21 (2.0% relative humidity,0.3 degree Celsius).

The devices communicate with the I2C protocol. All sensors are set to the sameI2C address 0x40, so an entry with I2C_BOARD_INFO(“sht21”, 0x40) can be usedin the board setup code.

sysfs-Interface¶

Notes¶

The driver uses the default resolution settings of 12 bit for humidity and 14bit for temperature, which results in typical measurement times of 22 ms forhumidity and 66 ms for temperature. To keep self heating below 0.1 degreeCelsius, the device should not be active for more than 10% of the time,e.g. maximum two measurements per second at the given resolution.

Different resolutions, the on-chip heater, and using the CRC checksumare not supported yet.