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- Kernel driver sht3x
- ===================
- Supported chips:
- * Sensirion SHT3x-DIS
- Prefix: 'sht3x'
- Addresses scanned: none
- Datasheet: http://www.sensirion.com/fileadmin/user_upload/customers/sensirion/Dokumente/Humidity/Sensirion_Humidity_Datasheet_SHT3x_DIS.pdf
- Author:
- David Frey <david.frey@sensirion.com>
- Pascal Sachs <pascal.sachs@sensirion.com>
- Description
- -----------
- This driver implements support for the Sensirion SHT3x-DIS chip, a humidity
- and temperature sensor. 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, depending on the wiring. See
- Documentation/i2c/instantiating-devices for methods to instantiate the device.
- There are two options configurable by means of sht3x_platform_data:
- 1. blocking (pull the I2C clock line down while performing the measurement) or
- non-blocking mode. Blocking mode will guarantee the fastest result but
- the I2C bus will be busy during that time. By default, non-blocking mode
- is used. Make sure clock-stretching works properly on your device if you
- want to use blocking mode.
- 2. high or low accuracy. High accuracy is used by default and using it is
- strongly recommended.
- 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.
- 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
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