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diff --git a/Documentation/hwmon/sht3x.rst b/Documentation/hwmon/sht3x.rst new file mode 100644 index 000000000000..9585fa7c5a5d --- /dev/null +++ b/Documentation/hwmon/sht3x.rst @@ -0,0 +1,112 @@ +Kernel driver sht3x +=================== + +Supported chips: + + * Sensirion SHT3x-DIS + + Prefix: 'sht3x' + + Addresses scanned: none + + Datasheets: + - https://sensirion.com/media/documents/213E6A3B/63A5A569/Datasheet_SHT3x_DIS.pdf + - https://sensirion.com/media/documents/051DF50B/639C8101/Sensirion_Humidity_and_Temperature_Sensors_Datasheet_SHT33.pdf + + * Sensirion STS3x-DIS + + Prefix: 'sts3x' + + Addresses scanned: none + + Datasheets: + - https://sensirion.com/media/documents/1DA31AFD/61641F76/Sensirion_Temperature_Sensors_STS3x_Datasheet.pdf + - https://sensirion.com/media/documents/292A335C/65537BAF/Sensirion_Datasheet_STS32_STS33.pdf + +Author: + + - David Frey <david.frey@sensirion.com> + - Pascal Sachs <pascal.sachs@sensirion.com> + +Description +----------- + +This driver implements support for the Sensirion SHT3x-DIS and STS3x-DIS +series of humidity and temperature sensors. Temperature is measured in degrees +celsius, relative humidity is expressed as a percentage. In the sysfs interface, +all values are scaled by 1000, i.e. the value for 31.5 degrees celsius is 31500. + +The device communicates with the I2C protocol. Sensors can have the I2C +addresses 0x44 or 0x45 (0x4a or 0x4b for sts3x), depending on the wiring. See +Documentation/i2c/instantiating-devices.rst for methods to instantiate the +device. + +Even if sht3x sensor supports clock-stretch (blocking mode) and non-stretch +(non-blocking mode) in single-shot mode, this driver only supports the latter. + +The sht3x sensor supports a single shot mode as well as 5 periodic measure +modes, which can be controlled with the update_interval sysfs interface. +The allowed update_interval in milliseconds are as follows: + + ===== ======= ==================== + 0 single shot mode + 2000 0.5 Hz periodic measurement + 1000 1 Hz periodic measurement + 500 2 Hz periodic measurement + 250 4 Hz periodic measurement + 100 10 Hz periodic measurement + ===== ======= ==================== + +In the periodic measure mode, the sensor automatically triggers a measurement +with the configured update interval on the chip. When a temperature or humidity +reading exceeds the configured limits, the alert attribute is set to 1 and +the alert pin on the sensor is set to high. +When the temperature and humidity readings move back between the hysteresis +values, the alert bit is set to 0 and the alert pin on the sensor is set to +low. + +The serial number exposed to debugfs allows for unique identification of the +sensors. For sts32, sts33 and sht33, the manufacturer provides calibration +certificates through an API. + +sysfs-Interface +--------------- + +=================== ============================================================ +temp1_input: temperature input +humidity1_input: humidity input +temp1_max: temperature max value +temp1_max_hyst: temperature hysteresis value for max limit +humidity1_max: humidity max value +humidity1_max_hyst: humidity hysteresis value for max limit +temp1_min: temperature min value +temp1_min_hyst: temperature hysteresis value for min limit +humidity1_min: humidity min value +humidity1_min_hyst: humidity hysteresis value for min limit +temp1_alarm: alarm flag is set to 1 if the temperature is outside the + configured limits. Alarm only works in periodic measure mode +humidity1_alarm: alarm flag is set to 1 if the humidity is outside the + configured limits. Alarm only works in periodic measure mode +heater_enable: heater enable, heating element removes excess humidity from + sensor: + + - 0: turned off + - 1: turned on +update_interval: update interval, 0 for single shot, interval in msec + for periodic measurement. If the interval is not supported + by the sensor, the next faster interval is chosen +repeatability: write or read repeatability, higher repeatability means + longer measurement duration, lower noise level and + larger energy consumption: + + - 0: low repeatability + - 1: medium repeatability + - 2: high repeatability +=================== ============================================================ + +debugfs-Interface +----------------- + +=================== ============================================================ +serial_number: unique serial number of the sensor in decimal +=================== ============================================================ |