1Kernel driver sht21 2=================== 3 4Supported chips: 5 6 * Sensirion SHT20 7 8 Prefix: 'sht20' 9 10 Addresses scanned: none 11 12 Datasheet: Publicly available at the Sensirion website 13 14 https://www.sensirion.com/file/datasheet_sht20 15 16 * Sensirion SHT21 17 18 Prefix: 'sht21' 19 20 Addresses scanned: none 21 22 Datasheet: Publicly available at the Sensirion website 23 24 https://www.sensirion.com/file/datasheet_sht21 25 26 * Sensirion SHT25 27 28 Prefix: 'sht25' 29 30 Addresses scanned: none 31 32 Datasheet: Publicly available at the Sensirion website 33 34 https://www.sensirion.com/file/datasheet_sht25 35 36Author: 37 38 Urs Fleisch <urs.fleisch@sensirion.com> 39 40Description 41----------- 42 43The SHT21 and SHT25 are humidity and temperature sensors in a DFN package of 44only 3 x 3 mm footprint and 1.1 mm height. The difference between the two 45devices is the higher level of precision of the SHT25 (1.8% relative humidity, 460.2 degree Celsius) compared with the SHT21 (2.0% relative humidity, 470.3 degree Celsius). 48 49The devices communicate with the I2C protocol. All sensors are set to the same 50I2C address 0x40, so an entry with I2C_BOARD_INFO("sht21", 0x40) can be used 51in the board setup code. 52 53sysfs-Interface 54--------------- 55 56=================== ============================================================ 57temp1_input Temperature input 58humidity1_input Humidity input 59eic Electronic Identification Code 60=================== ============================================================ 61 62Notes 63----- 64 65The driver uses the default resolution settings of 12 bit for humidity and 14 66bit for temperature, which results in typical measurement times of 22 ms for 67humidity and 66 ms for temperature. To keep self heating below 0.1 degree 68Celsius, the device should not be active for more than 10% of the time, 69e.g. maximum two measurements per second at the given resolution. 70 71Different resolutions, the on-chip heater, and using the CRC checksum 72are not supported yet. 73