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Commit | Line | Data |
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99a0378d VD |
1 | Kernel driver sht15 |
2 | =================== | |
3 | ||
4 | Authors: | |
b04f2f7d | 5 | |
99a0378d VD |
6 | * Wouter Horre |
7 | * Jonathan Cameron | |
cc15c7eb | 8 | * Vivien Didelot <vivien.didelot@savoirfairelinux.com> |
82c7465b | 9 | * Jerome Oufella <jerome.oufella@savoirfairelinux.com> |
99a0378d VD |
10 | |
11 | Supported chips: | |
b04f2f7d | 12 | |
99a0378d | 13 | * Sensirion SHT10 |
b04f2f7d | 14 | |
99a0378d VD |
15 | Prefix: 'sht10' |
16 | ||
17 | * Sensirion SHT11 | |
b04f2f7d | 18 | |
99a0378d VD |
19 | Prefix: 'sht11' |
20 | ||
21 | * Sensirion SHT15 | |
b04f2f7d | 22 | |
99a0378d VD |
23 | Prefix: 'sht15' |
24 | ||
25 | * Sensirion SHT71 | |
b04f2f7d | 26 | |
99a0378d VD |
27 | Prefix: 'sht71' |
28 | ||
29 | * Sensirion SHT75 | |
b04f2f7d | 30 | |
99a0378d VD |
31 | Prefix: 'sht75' |
32 | ||
33 | Datasheet: Publicly available at the Sensirion website | |
b04f2f7d MCC |
34 | |
35 | http://www.sensirion.ch/en/pdf/product_information/Datasheet-humidity-sensor-SHT1x.pdf | |
99a0378d VD |
36 | |
37 | Description | |
38 | ----------- | |
39 | ||
40 | The SHT10, SHT11, SHT15, SHT71, and SHT75 are humidity and temperature | |
41 | sensors. | |
42 | ||
cc15c7eb VD |
43 | The devices communicate using two GPIO lines. |
44 | ||
45 | Supported resolutions for the measurements are 14 bits for temperature and 12 | |
46 | bits for humidity, or 12 bits for temperature and 8 bits for humidity. | |
47 | ||
48 | The humidity calibration coefficients are programmed into an OTP memory on the | |
49 | chip. These coefficients are used to internally calibrate the signals from the | |
50 | sensors. Disabling the reload of those coefficients allows saving 10ms for each | |
1754e4c5 | 51 | measurement and decrease power consumption, while losing on precision. |
cc15c7eb | 52 | |
18673114 | 53 | Some options may be set via sysfs attributes. |
99a0378d | 54 | |
82c7465b JO |
55 | Notes: |
56 | * The regulator supply name is set to "vcc". | |
57 | * If a CRC validation fails, a soft reset command is sent, which resets | |
58 | status register to its hardware default value, but the driver will try to | |
59 | restore the previous device configuration. | |
99a0378d | 60 | |
cc15c7eb VD |
61 | Platform data |
62 | ------------- | |
63 | ||
82c7465b JO |
64 | * checksum: |
65 | set it to true to enable CRC validation of the readings (default to false). | |
cc15c7eb VD |
66 | * no_otp_reload: |
67 | flag to indicate not to reload from OTP (default to false). | |
68 | * low_resolution: | |
69 | flag to indicate the temp/humidity resolution to use (default to false). | |
70 | ||
99a0378d VD |
71 | Sysfs interface |
72 | --------------- | |
73 | ||
b04f2f7d MCC |
74 | ================== ========================================================== |
75 | temp1_input temperature input | |
76 | humidity1_input humidity input | |
77 | heater_enable write 1 in this attribute to enable the on-chip heater, | |
78 | 0 to disable it. Be careful not to enable the heater | |
79 | for too long. | |
80 | temp1_fault if 1, this means that the voltage is low (below 2.47V) and | |
81 | measurement may be invalid. | |
82 | humidity1_fault same as temp1_fault. | |
83 | ================== ========================================================== |