1Kernel driver sht3x 2=================== 3 4Supported chips: 5 6 * Sensirion SHT3x-DIS 7 8 Prefix: 'sht3x' 9 10 Addresses scanned: none 11 12 Datasheets: 13 - https://sensirion.com/media/documents/213E6A3B/63A5A569/Datasheet_SHT3x_DIS.pdf 14 - https://sensirion.com/media/documents/051DF50B/639C8101/Sensirion_Humidity_and_Temperature_Sensors_Datasheet_SHT33.pdf 15 16 * Sensirion STS3x-DIS 17 18 Prefix: 'sts3x' 19 20 Addresses scanned: none 21 22 Datasheets: 23 - https://sensirion.com/media/documents/1DA31AFD/61641F76/Sensirion_Temperature_Sensors_STS3x_Datasheet.pdf 24 - https://sensirion.com/media/documents/292A335C/65537BAF/Sensirion_Datasheet_STS32_STS33.pdf 25 26 * Sensirion SHT85 27 28 Prefix: 'sht85' 29 30 Addresses scanned: none 31 32 Datasheet: https://sensirion.com/media/documents/4B40CEF3/640B2346/Sensirion_Humidity_Sensors_SHT85_Datasheet.pdf 33 34Author: 35 36 - David Frey <david.frey@sensirion.com> 37 - Pascal Sachs <pascal.sachs@sensirion.com> 38 39Description 40----------- 41 42This driver implements support for the Sensirion SHT3x-DIS, STS3x-DIS and SHT85 43series of humidity and temperature sensors. Temperature is measured in degrees 44celsius, relative humidity is expressed as a percentage. In the sysfs interface, 45all values are scaled by 1000, i.e. the value for 31.5 degrees celsius is 31500. 46 47The device communicates with the I2C protocol. SHT3x sensors can have the I2C 48addresses 0x44 or 0x45 (0x4a or 0x4b for sts3x), depending on the wiring. SHT85 49address is 0x44 and is fixed. See Documentation/i2c/instantiating-devices.rst for 50methods to instantiate the device. 51 52Even if sht3x sensor supports clock-stretch (blocking mode) and non-stretch 53(non-blocking mode) in single-shot mode, this driver only supports the latter. 54 55The sht3x sensor supports a single shot mode as well as 5 periodic measure 56modes, which can be controlled with the update_interval sysfs interface. 57The allowed update_interval in milliseconds are as follows: 58 59 ===== ======= ==================== 60 0 single shot mode 61 2000 0.5 Hz periodic measurement 62 1000 1 Hz periodic measurement 63 500 2 Hz periodic measurement 64 250 4 Hz periodic measurement 65 100 10 Hz periodic measurement 66 ===== ======= ==================== 67 68In the periodic measure mode, the sensor automatically triggers a measurement 69with the configured update interval on the chip. When a temperature or humidity 70reading exceeds the configured limits, the alert attribute is set to 1 and 71the alert pin on the sensor is set to high. 72When the temperature and humidity readings move back between the hysteresis 73values, the alert bit is set to 0 and the alert pin on the sensor is set to 74low. 75 76The serial number exposed to debugfs allows for unique identification of the 77sensors. For sts32, sts33 and sht33, the manufacturer provides calibration 78certificates through an API. 79 80sysfs-Interface 81--------------- 82 83=================== ============================================================ 84temp1_input: temperature input 85humidity1_input: humidity input 86temp1_max: temperature max value 87temp1_max_hyst: temperature hysteresis value for max limit 88humidity1_max: humidity max value 89humidity1_max_hyst: humidity hysteresis value for max limit 90temp1_min: temperature min value 91temp1_min_hyst: temperature hysteresis value for min limit 92humidity1_min: humidity min value 93humidity1_min_hyst: humidity hysteresis value for min limit 94temp1_alarm: alarm flag is set to 1 if the temperature is outside the 95 configured limits. Alarm only works in periodic measure mode 96humidity1_alarm: alarm flag is set to 1 if the humidity is outside the 97 configured limits. Alarm only works in periodic measure mode 98heater_enable: heater enable, heating element removes excess humidity from 99 sensor: 100 101 - 0: turned off 102 - 1: turned on 103update_interval: update interval, 0 for single shot, interval in msec 104 for periodic measurement. If the interval is not supported 105 by the sensor, the next faster interval is chosen 106repeatability: write or read repeatability, higher repeatability means 107 longer measurement duration, lower noise level and 108 larger energy consumption: 109 110 - 0: low repeatability 111 - 1: medium repeatability 112 - 2: high repeatability 113=================== ============================================================ 114 115debugfs-Interface 116----------------- 117 118=================== ============================================================ 119serial_number: unique serial number of the sensor in decimal 120=================== ============================================================ 121