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Vivien Didelot99a03782011-04-12 15:34:36 -04001Kernel driver sht15
2===================
3
4Authors:
5 * Wouter Horre
6 * Jonathan Cameron
Vivien Didelotcc15c7e2011-04-12 15:34:38 -04007 * Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Jerome Oufella82c74652011-04-12 15:34:39 -04008 * Jerome Oufella <jerome.oufella@savoirfairelinux.com>
Vivien Didelot99a03782011-04-12 15:34:36 -04009
10Supported 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
26Datasheet: Publicly available at the Sensirion website
27http://www.sensirion.ch/en/pdf/product_information/Datasheet-humidity-sensor-SHT1x.pdf
28
29Description
30-----------
31
32The SHT10, SHT11, SHT15, SHT71, and SHT75 are humidity and temperature
33sensors.
34
Vivien Didelotcc15c7e2011-04-12 15:34:38 -040035The devices communicate using two GPIO lines.
36
37Supported resolutions for the measurements are 14 bits for temperature and 12
38bits for humidity, or 12 bits for temperature and 8 bits for humidity.
39
40The humidity calibration coefficients are programmed into an OTP memory on the
41chip. These coefficients are used to internally calibrate the signals from the
42sensors. Disabling the reload of those coefficients allows saving 10ms for each
43measurement and decrease power consumption, while loosing on precision.
44
45Some options may be set directly in the sht15_platform_data structure
46or via sysfs attributes.
Vivien Didelot99a03782011-04-12 15:34:36 -040047
Jerome Oufella82c74652011-04-12 15:34:39 -040048Notes:
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.
Vivien Didelot99a03782011-04-12 15:34:36 -040053
Vivien Didelotcc15c7e2011-04-12 15:34:38 -040054Platform data
55-------------
56
Jerome Oufella82c74652011-04-12 15:34:39 -040057* checksum:
58 set it to true to enable CRC validation of the readings (default to false).
Vivien Didelotcc15c7e2011-04-12 15:34:38 -040059* 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
Vivien Didelot99a03782011-04-12 15:34:36 -040064Sysfs interface
65---------------
66
67* temp1_input: temperature input
68* humidity1_input: humidity input
Vivien Didelotcc15c7e2011-04-12 15:34:38 -040069* 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.