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