| 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 |