84 lines
2.3 KiB
ReStructuredText
84 lines
2.3 KiB
ReStructuredText
|
Kernel driver sht15
|
||
|
|
===================
|
||
|
|
|
||
|
|
Authors:
|
||
|
|
|
||
|
|
* Wouter Horre
|
||
|
|
* Jonathan Cameron
|
||
|
|
* Vivien Didelot <vivien.didelot@savoirfairelinux.com>
|
||
|
|
* Jerome Oufella <jerome.oufella@savoirfairelinux.com>
|
||
|
|
|
||
|
|
Supported chips:
|
||
|
|
|
||
|
|
* Sensirion SHT10
|
||
|
|
|
||
|
|
Prefix: 'sht10'
|
||
|
|
|
||
|
|
* Sensirion SHT11
|
||
|
|
|
||
|
|
Prefix: 'sht11'
|
||
|
|
|
||
|
|
* Sensirion SHT15
|
||
|
|
|
||
|
|
Prefix: 'sht15'
|
||
|
|
|
||
|
|
* Sensirion SHT71
|
||
|
|
|
||
|
|
Prefix: 'sht71'
|
||
|
|
|
||
|
|
* Sensirion SHT75
|
||
|
|
|
||
|
|
Prefix: 'sht75'
|
||
|
|
|
||
|
|
Datasheet: Publicly available at the Sensirion website
|
||
|
|
|
||
|
|
http://www.sensirion.ch/en/pdf/product_information/Datasheet-humidity-sensor-SHT1x.pdf
|
||
|
|
|
||
|
|
Description
|
||
|
|
-----------
|
||
|
|
|
||
|
|
The SHT10, SHT11, SHT15, SHT71, and SHT75 are humidity and temperature
|
||
|
|
sensors.
|
||
|
|
|
||
|
|
The devices communicate using two GPIO lines.
|
||
|
|
|
||
|
|
Supported resolutions for the measurements are 14 bits for temperature and 12
|
||
|
|
bits for humidity, or 12 bits for temperature and 8 bits for humidity.
|
||
|
|
|
||
|
|
The humidity calibration coefficients are programmed into an OTP memory on the
|
||
|
|
chip. These coefficients are used to internally calibrate the signals from the
|
||
|
|
sensors. Disabling the reload of those coefficients allows saving 10ms for each
|
||
|
|
measurement and decrease power consumption, while losing on precision.
|
||
|
|
|
||
|
|
Some options may be set via sysfs attributes.
|
||
|
|
|
||
|
|
Notes:
|
||
|
|
* The regulator supply name is set to "vcc".
|
||
|
|
* If a CRC validation fails, a soft reset command is sent, which resets
|
||
|
|
status register to its hardware default value, but the driver will try to
|
||
|
|
restore the previous device configuration.
|
||
|
|
|
||
|
|
Platform data
|
||
|
|
-------------
|
||
|
|
|
||
|
|
* checksum:
|
||
|
|
set it to true to enable CRC validation of the readings (default to false).
|
||
|
|
* no_otp_reload:
|
||
|
|
flag to indicate not to reload from OTP (default to false).
|
||
|
|
* low_resolution:
|
||
|
|
flag to indicate the temp/humidity resolution to use (default to false).
|
||
|
|
|
||
|
|
Sysfs interface
|
||
|
|
---------------
|
||
|
|
|
||
|
|
================== ==========================================================
|
||
|
|
temp1_input temperature input
|
||
|
|
humidity1_input humidity input
|
||
|
|
heater_enable write 1 in this attribute to enable the on-chip heater,
|
||
|
|
0 to disable it. Be careful not to enable the heater
|
||
|
|
for too long.
|
||
|
|
temp1_fault if 1, this means that the voltage is low (below 2.47V) and
|
||
|
|
measurement may be invalid.
|
||
|
|
humidity1_fault same as temp1_fault.
|
||
|
|
================== ==========================================================
|