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The sht15 sensor allows validating exchanges to and from the device using a crc8 function. An utility function to reverse a byte has also been added. Signed-off-by: Jerome Oufella <jerome.oufella@savoirfairelinux.com> Acked-by: Jonathan Cameron <jic23@cam.ac.uk> Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
75 lines
2.2 KiB
Plaintext
75 lines
2.2 KiB
Plaintext
Kernel driver sht15
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===================
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Authors:
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* Wouter Horre
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* Jonathan Cameron
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* Vivien Didelot <vivien.didelot@savoirfairelinux.com>
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* Jerome Oufella <jerome.oufella@savoirfairelinux.com>
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Supported chips:
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* Sensirion SHT10
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Prefix: 'sht10'
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* Sensirion SHT11
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Prefix: 'sht11'
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* Sensirion SHT15
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Prefix: 'sht15'
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* Sensirion SHT71
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Prefix: 'sht71'
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* Sensirion SHT75
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Prefix: 'sht75'
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Datasheet: Publicly available at the Sensirion website
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http://www.sensirion.ch/en/pdf/product_information/Datasheet-humidity-sensor-SHT1x.pdf
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Description
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-----------
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The SHT10, SHT11, SHT15, SHT71, and SHT75 are humidity and temperature
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sensors.
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The devices communicate using two GPIO lines.
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Supported resolutions for the measurements are 14 bits for temperature and 12
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bits for humidity, or 12 bits for temperature and 8 bits for humidity.
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The humidity calibration coefficients are programmed into an OTP memory on the
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chip. These coefficients are used to internally calibrate the signals from the
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sensors. Disabling the reload of those coefficients allows saving 10ms for each
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measurement and decrease power consumption, while loosing on precision.
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Some options may be set directly in the sht15_platform_data structure
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or via sysfs attributes.
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Notes:
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* The regulator supply name is set to "vcc".
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* If a CRC validation fails, a soft reset command is sent, which resets
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status register to its hardware default value, but the driver will try to
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restore the previous device configuration.
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Platform data
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-------------
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* checksum:
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set it to true to enable CRC validation of the readings (default to false).
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* no_otp_reload:
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flag to indicate not to reload from OTP (default to false).
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* low_resolution:
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flag to indicate the temp/humidity resolution to use (default to false).
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Sysfs interface
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---------------
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* temp1_input: temperature input
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* humidity1_input: humidity input
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* heater_enable: write 1 in this attribute to enable the on-chip heater,
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0 to disable it. Be careful not to enable the heater
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for too long.
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* temp1_fault: if 1, this means that the voltage is low (below 2.47V) and
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measurement may be invalid.
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* humidity1_fault: same as temp1_fault.
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