| Kernel driver sht3x |
| =================== |
| |
| Supported chips: |
| * Sensirion SHT3x-DIS |
| Prefix: 'sht3x' |
| Addresses scanned: none |
| Datasheet: https://www.sensirion.com/file/datasheet_sht3x_digital |
| |
| 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 |