projects / linux-2.6-block.git / blame
| Commit | Line | Data |
|---|---|---|
| 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 | ================== ========================================================== |