1Kernel driver sht3x
2===================
3
4Supported chips:
5  * Sensirion SHT3x-DIS
6    Prefix: 'sht3x'
7    Addresses scanned: none
8    Datasheet: https://www.sensirion.com/file/datasheet_sht3x_digital
9
10Author:
11  David Frey <david.frey@sensirion.com>
12  Pascal Sachs <pascal.sachs@sensirion.com>
13
14Description
15-----------
16
17This driver implements support for the Sensirion SHT3x-DIS chip, a humidity
18and temperature sensor. Temperature is measured in degrees celsius, relative
19humidity is expressed as a percentage. In the sysfs interface, all values are
20scaled by 1000, i.e. the value for 31.5 degrees celsius is 31500.
21
22The device communicates with the I2C protocol. Sensors can have the I2C
23addresses 0x44 or 0x45, depending on the wiring. See
24Documentation/i2c/instantiating-devices for methods to instantiate the device.
25
26There are two options configurable by means of sht3x_platform_data:
271. blocking (pull the I2C clock line down while performing the measurement) or
28   non-blocking mode. Blocking mode will guarantee the fastest result but
29   the I2C bus will be busy during that time. By default, non-blocking mode
30   is used. Make sure clock-stretching works properly on your device if you
31   want to use blocking mode.
322. high or low accuracy. High accuracy is used by default and using it is
33   strongly recommended.
34
35The sht3x sensor supports a single shot mode as well as 5 periodic measure
36modes, which can be controlled with the update_interval sysfs interface.
37The allowed update_interval in milliseconds are as follows:
38  *     0   single shot mode
39  *  2000   0.5 Hz periodic measurement
40  *  1000   1   Hz periodic measurement
41  *   500   2   Hz periodic measurement
42  *   250   4   Hz periodic measurement
43  *   100  10   Hz periodic measurement
44
45In the periodic measure mode, the sensor automatically triggers a measurement
46with the configured update interval on the chip. When a temperature or humidity
47reading exceeds the configured limits, the alert attribute is set to 1 and
48the alert pin on the sensor is set to high.
49When the temperature and humidity readings move back between the hysteresis
50values, the alert bit is set to 0 and the alert pin on the sensor is set to
51low.
52
53sysfs-Interface
54---------------
55
56temp1_input:        temperature input
57humidity1_input:    humidity input
58temp1_max:          temperature max value
59temp1_max_hyst:     temperature hysteresis value for max limit
60humidity1_max:      humidity max value
61humidity1_max_hyst: humidity hysteresis value for max limit
62temp1_min:          temperature min value
63temp1_min_hyst:     temperature hysteresis value for min limit
64humidity1_min:      humidity min value
65humidity1_min_hyst: humidity hysteresis value for min limit
66temp1_alarm:        alarm flag is set to 1 if the temperature is outside the
67                    configured limits. Alarm only works in periodic measure mode
68humidity1_alarm:    alarm flag is set to 1 if the humidity is outside the
69                    configured limits. Alarm only works in periodic measure mode
70heater_enable:      heater enable, heating element removes excess humidity from
71                    sensor
72                        0: turned off
73                        1: turned on
74update_interval:    update interval, 0 for single shot, interval in msec
75                    for periodic measurement. If the interval is not supported
76                    by the sensor, the next faster interval is chosen
77