Based on kernel version 4.16.1. Page generated on 2018-04-09 11:53 EST.
1 Kernel driver sht21 2 =================== 3 4 Supported chips: 5 * Sensirion SHT21 6 Prefix: 'sht21' 7 Addresses scanned: none 8 Datasheet: Publicly available at the Sensirion website 9 http://www.sensirion.com/en/pdf/product_information/Datasheet-humidity-sensor-SHT21.pdf 10 11 * Sensirion SHT25 12 Prefix: 'sht21' 13 Addresses scanned: none 14 Datasheet: Publicly available at the Sensirion website 15 http://www.sensirion.com/en/pdf/product_information/Datasheet-humidity-sensor-SHT25.pdf 16 17 Author: 18 Urs Fleisch <urs.fleisch@sensirion.com> 19 20 Description 21 ----------- 22 23 The SHT21 and SHT25 are humidity and temperature sensors in a DFN package of 24 only 3 x 3 mm footprint and 1.1 mm height. The difference between the two 25 devices is the higher level of precision of the SHT25 (1.8% relative humidity, 26 0.2 degree Celsius) compared with the SHT21 (2.0% relative humidity, 27 0.3 degree Celsius). 28 29 The devices communicate with the I2C protocol. All sensors are set to the same 30 I2C address 0x40, so an entry with I2C_BOARD_INFO("sht21", 0x40) can be used 31 in the board setup code. 32 33 sysfs-Interface 34 --------------- 35 36 temp1_input - temperature input 37 humidity1_input - humidity input 38 eic - Electronic Identification Code 39 40 Notes 41 ----- 42 43 The driver uses the default resolution settings of 12 bit for humidity and 14 44 bit for temperature, which results in typical measurement times of 22 ms for 45 humidity and 66 ms for temperature. To keep self heating below 0.1 degree 46 Celsius, the device should not be active for more than 10% of the time, 47 e.g. maximum two measurements per second at the given resolution. 48 49 Different resolutions, the on-chip heater, and using the CRC checksum 50 are not supported yet.