1Kernel driver sht3x 2=================== 3 4Supported chips: 5 6 * Sensirion SHT3x-DIS 7 8 Prefix: 'sht3x' 9 10 Addresses scanned: none 11 12 Datasheet: https://www.sensirion.com/file/datasheet_sht3x_digital 13 14Author: 15 16 - David Frey <david.frey@sensirion.com> 17 - Pascal Sachs <pascal.sachs@sensirion.com> 18 19Description 20----------- 21 22This driver implements support for the Sensirion SHT3x-DIS chip, a humidity 23and temperature sensor. Temperature is measured in degrees celsius, relative 24humidity is expressed as a percentage. In the sysfs interface, all values are 25scaled by 1000, i.e. the value for 31.5 degrees celsius is 31500. 26 27The device communicates with the I2C protocol. Sensors can have the I2C 28addresses 0x44 or 0x45, depending on the wiring. See 29Documentation/i2c/instantiating-devices.rst for methods to instantiate the device. 30 31Even if sht3x sensor supports clock-strech(blocking mode) and non-strench 32(non-blocking mode) in single-shot mode, this driver only supports the latter. 33 34The sht3x sensor supports a single shot mode as well as 5 periodic measure 35modes, which can be controlled with the update_interval sysfs interface. 36The allowed update_interval in milliseconds are as follows: 37 38 ===== ======= ==================== 39 0 single shot mode 40 2000 0.5 Hz periodic measurement 41 1000 1 Hz periodic measurement 42 500 2 Hz periodic measurement 43 250 4 Hz periodic measurement 44 100 10 Hz periodic measurement 45 ===== ======= ==================== 46 47In the periodic measure mode, the sensor automatically triggers a measurement 48with the configured update interval on the chip. When a temperature or humidity 49reading exceeds the configured limits, the alert attribute is set to 1 and 50the alert pin on the sensor is set to high. 51When the temperature and humidity readings move back between the hysteresis 52values, the alert bit is set to 0 and the alert pin on the sensor is set to 53low. 54 55sysfs-Interface 56--------------- 57 58=================== ============================================================ 59temp1_input: temperature input 60humidity1_input: humidity input 61temp1_max: temperature max value 62temp1_max_hyst: temperature hysteresis value for max limit 63humidity1_max: humidity max value 64humidity1_max_hyst: humidity hysteresis value for max limit 65temp1_min: temperature min value 66temp1_min_hyst: temperature hysteresis value for min limit 67humidity1_min: humidity min value 68humidity1_min_hyst: humidity hysteresis value for min limit 69temp1_alarm: alarm flag is set to 1 if the temperature is outside the 70 configured limits. Alarm only works in periodic measure mode 71humidity1_alarm: alarm flag is set to 1 if the humidity is outside the 72 configured limits. Alarm only works in periodic measure mode 73heater_enable: heater enable, heating element removes excess humidity from 74 sensor: 75 76 - 0: turned off 77 - 1: turned on 78update_interval: update interval, 0 for single shot, interval in msec 79 for periodic measurement. If the interval is not supported 80 by the sensor, the next faster interval is chosen 81repeatability: write or read repeatability, higher repeatability means 82 longer measurement duration, lower noise level and 83 larger energy consumption: 84 85 - 0: low repeatability 86 - 1: medium repeatability 87 - 2: high repeatability 88=================== ============================================================ 89