sht3x.rst (3579B)
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 31There are two options configurable by means of sht3x_platform_data: 32 331. blocking (pull the I2C clock line down while performing the measurement) or 34 non-blocking mode. Blocking mode will guarantee the fastest result but 35 the I2C bus will be busy during that time. By default, non-blocking mode 36 is used. Make sure clock-stretching works properly on your device if you 37 want to use blocking mode. 382. high or low accuracy. High accuracy is used by default and using it is 39 strongly recommended. 40 41The sht3x sensor supports a single shot mode as well as 5 periodic measure 42modes, which can be controlled with the update_interval sysfs interface. 43The allowed update_interval in milliseconds are as follows: 44 45 ===== ======= ==================== 46 0 single shot mode 47 2000 0.5 Hz periodic measurement 48 1000 1 Hz periodic measurement 49 500 2 Hz periodic measurement 50 250 4 Hz periodic measurement 51 100 10 Hz periodic measurement 52 ===== ======= ==================== 53 54In the periodic measure mode, the sensor automatically triggers a measurement 55with the configured update interval on the chip. When a temperature or humidity 56reading exceeds the configured limits, the alert attribute is set to 1 and 57the alert pin on the sensor is set to high. 58When the temperature and humidity readings move back between the hysteresis 59values, the alert bit is set to 0 and the alert pin on the sensor is set to 60low. 61 62sysfs-Interface 63--------------- 64 65=================== ============================================================ 66temp1_input: temperature input 67humidity1_input: humidity input 68temp1_max: temperature max value 69temp1_max_hyst: temperature hysteresis value for max limit 70humidity1_max: humidity max value 71humidity1_max_hyst: humidity hysteresis value for max limit 72temp1_min: temperature min value 73temp1_min_hyst: temperature hysteresis value for min limit 74humidity1_min: humidity min value 75humidity1_min_hyst: humidity hysteresis value for min limit 76temp1_alarm: alarm flag is set to 1 if the temperature is outside the 77 configured limits. Alarm only works in periodic measure mode 78humidity1_alarm: alarm flag is set to 1 if the humidity is outside the 79 configured limits. Alarm only works in periodic measure mode 80heater_enable: heater enable, heating element removes excess humidity from 81 sensor: 82 83 - 0: turned off 84 - 1: turned on 85update_interval: update interval, 0 for single shot, interval in msec 86 for periodic measurement. If the interval is not supported 87 by the sensor, the next faster interval is chosen 88=================== ============================================================