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- 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
- * Sensirion SHT85
- Prefix: 'sht85'
- Addresses scanned: none
- Datasheet: https://sensirion.com/media/documents/4B40CEF3/640B2346/Sensirion_Humidity_Sensors_SHT85_Datasheet.pdf
- Author:
- - David Frey <david.frey@sensirion.com>
- - Pascal Sachs <pascal.sachs@sensirion.com>
- Description
- -----------
- This driver implements support for the Sensirion SHT3x-DIS, STS3x-DIS and SHT85
- 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. SHT3x sensors can have the I2C
- addresses 0x44 or 0x45 (0x4a or 0x4b for sts3x), depending on the wiring. SHT85
- address is 0x44 and is fixed. 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
- =================== ============================================================
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