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99a0378d VD |
1 | Kernel driver sht15 |
2 | =================== | |
3 | ||
4 | Authors: | |
5 | * Wouter Horre | |
6 | * Jonathan Cameron | |
cc15c7eb | 7 | * Vivien Didelot <vivien.didelot@savoirfairelinux.com> |
82c7465b | 8 | * Jerome Oufella <jerome.oufella@savoirfairelinux.com> |
99a0378d VD |
9 | |
10 | Supported chips: | |
11 | * Sensirion SHT10 | |
12 | Prefix: 'sht10' | |
13 | ||
14 | * Sensirion SHT11 | |
15 | Prefix: 'sht11' | |
16 | ||
17 | * Sensirion SHT15 | |
18 | Prefix: 'sht15' | |
19 | ||
20 | * Sensirion SHT71 | |
21 | Prefix: 'sht71' | |
22 | ||
23 | * Sensirion SHT75 | |
24 | Prefix: 'sht75' | |
25 | ||
26 | Datasheet: Publicly available at the Sensirion website | |
27 | http://www.sensirion.ch/en/pdf/product_information/Datasheet-humidity-sensor-SHT1x.pdf | |
28 | ||
29 | Description | |
30 | ----------- | |
31 | ||
32 | The SHT10, SHT11, SHT15, SHT71, and SHT75 are humidity and temperature | |
33 | sensors. | |
34 | ||
cc15c7eb VD |
35 | The devices communicate using two GPIO lines. |
36 | ||
37 | Supported resolutions for the measurements are 14 bits for temperature and 12 | |
38 | bits for humidity, or 12 bits for temperature and 8 bits for humidity. | |
39 | ||
40 | The humidity calibration coefficients are programmed into an OTP memory on the | |
41 | chip. These coefficients are used to internally calibrate the signals from the | |
42 | sensors. Disabling the reload of those coefficients allows saving 10ms for each | |
43 | measurement and decrease power consumption, while loosing on precision. | |
44 | ||
45 | Some options may be set directly in the sht15_platform_data structure | |
46 | or via sysfs attributes. | |
99a0378d | 47 | |
82c7465b JO |
48 | Notes: |
49 | * The regulator supply name is set to "vcc". | |
50 | * If a CRC validation fails, a soft reset command is sent, which resets | |
51 | status register to its hardware default value, but the driver will try to | |
52 | restore the previous device configuration. | |
99a0378d | 53 | |
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54 | Platform data |
55 | ------------- | |
56 | ||
82c7465b JO |
57 | * checksum: |
58 | set it to true to enable CRC validation of the readings (default to false). | |
cc15c7eb VD |
59 | * no_otp_reload: |
60 | flag to indicate not to reload from OTP (default to false). | |
61 | * low_resolution: | |
62 | flag to indicate the temp/humidity resolution to use (default to false). | |
63 | ||
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64 | Sysfs interface |
65 | --------------- | |
66 | ||
67 | * temp1_input: temperature input | |
68 | * humidity1_input: humidity input | |
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69 | * heater_enable: write 1 in this attribute to enable the on-chip heater, |
70 | 0 to disable it. Be careful not to enable the heater | |
71 | for too long. | |
72 | * temp1_fault: if 1, this means that the voltage is low (below 2.47V) and | |
73 | measurement may be invalid. | |
74 | * humidity1_fault: same as temp1_fault. |