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1 | Kernel driver sht3x |
2 | =================== | |
3 | ||
4 | Supported chips: | |
b04f2f7d | 5 | |
7c84f7f8 | 6 | * Sensirion SHT3x-DIS |
b04f2f7d | 7 | |
7c84f7f8 | 8 | Prefix: 'sht3x' |
b04f2f7d | 9 | |
7c84f7f8 | 10 | Addresses scanned: none |
b04f2f7d | 11 | |
b20edea9 | 12 | Datasheet: https://www.sensirion.com/file/datasheet_sht3x_digital |
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13 | |
14 | Author: | |
b04f2f7d MCC |
15 | |
16 | - David Frey <david.frey@sensirion.com> | |
17 | - Pascal Sachs <pascal.sachs@sensirion.com> | |
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18 | |
19 | Description | |
20 | ----------- | |
21 | ||
22 | This driver implements support for the Sensirion SHT3x-DIS chip, a humidity | |
23 | and temperature sensor. Temperature is measured in degrees celsius, relative | |
24 | humidity is expressed as a percentage. In the sysfs interface, all values are | |
25 | scaled by 1000, i.e. the value for 31.5 degrees celsius is 31500. | |
26 | ||
27 | The device communicates with the I2C protocol. Sensors can have the I2C | |
28 | addresses 0x44 or 0x45, depending on the wiring. See | |
29 | Documentation/i2c/instantiating-devices for methods to instantiate the device. | |
30 | ||
31 | There are two options configurable by means of sht3x_platform_data: | |
b04f2f7d | 32 | |
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33 | 1. blocking (pull the I2C clock line down while performing the measurement) or |
34 | non-blocking mode. Blocking mode will guarantee the fastest result but | |
35 | the I2C bus will be busy during that time. By default, non-blocking mode | |
36 | is used. Make sure clock-stretching works properly on your device if you | |
37 | want to use blocking mode. | |
38 | 2. high or low accuracy. High accuracy is used by default and using it is | |
39 | strongly recommended. | |
40 | ||
41 | The sht3x sensor supports a single shot mode as well as 5 periodic measure | |
42 | modes, which can be controlled with the update_interval sysfs interface. | |
43 | The allowed update_interval in milliseconds are as follows: | |
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44 | |
45 | ===== ======= ==================== | |
46 | 0 single shot mode | |
47 | 2000 0.5 Hz periodic measurement | |
48 | 1000 1 Hz periodic measurement | |
49 | 500 2 Hz periodic measurement | |
50 | 250 4 Hz periodic measurement | |
51 | 100 10 Hz periodic measurement | |
52 | ===== ======= ==================== | |
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53 | |
54 | In the periodic measure mode, the sensor automatically triggers a measurement | |
55 | with the configured update interval on the chip. When a temperature or humidity | |
56 | reading exceeds the configured limits, the alert attribute is set to 1 and | |
57 | the alert pin on the sensor is set to high. | |
58 | When the temperature and humidity readings move back between the hysteresis | |
59 | values, the alert bit is set to 0 and the alert pin on the sensor is set to | |
60 | low. | |
61 | ||
62 | sysfs-Interface | |
63 | --------------- | |
64 | ||
b04f2f7d | 65 | =================== ============================================================ |
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66 | temp1_input: temperature input |
67 | humidity1_input: humidity input | |
68 | temp1_max: temperature max value | |
69 | temp1_max_hyst: temperature hysteresis value for max limit | |
70 | humidity1_max: humidity max value | |
71 | humidity1_max_hyst: humidity hysteresis value for max limit | |
72 | temp1_min: temperature min value | |
73 | temp1_min_hyst: temperature hysteresis value for min limit | |
74 | humidity1_min: humidity min value | |
75 | humidity1_min_hyst: humidity hysteresis value for min limit | |
76 | temp1_alarm: alarm flag is set to 1 if the temperature is outside the | |
b04f2f7d | 77 | configured limits. Alarm only works in periodic measure mode |
7c84f7f8 | 78 | humidity1_alarm: alarm flag is set to 1 if the humidity is outside the |
b04f2f7d | 79 | configured limits. Alarm only works in periodic measure mode |
50c22cd1 | 80 | heater_enable: heater enable, heating element removes excess humidity from |
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81 | sensor: |
82 | ||
83 | - 0: turned off | |
84 | - 1: turned on | |
7c84f7f8 | 85 | update_interval: update interval, 0 for single shot, interval in msec |
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86 | for periodic measurement. If the interval is not supported |
87 | by the sensor, the next faster interval is chosen | |
88 | =================== ============================================================ |