47 lines
1.4 KiB
Text
47 lines
1.4 KiB
Text
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Kernel driver htu21
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===================
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Supported chips:
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* Measurement Specialties HTU21D
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Prefix: 'htu21'
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Addresses scanned: none
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Datasheet: Publicly available at the Measurement Specialties website
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http://www.meas-spec.com/downloads/HTU21D.pdf
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Author:
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William Markezana <william.markezana@meas-spec.com>
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Description
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-----------
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The HTU21D is a humidity and temperature sensor in a DFN package of
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only 3 x 3 mm footprint and 0.9 mm height.
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The devices communicate with the I2C protocol. All sensors are set to the
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same I2C address 0x40, so an entry with I2C_BOARD_INFO("htu21", 0x40) can
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be used in the board setup code.
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This driver does not auto-detect devices. You will have to instantiate the
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devices explicitly. Please see Documentation/i2c/instantiating-devices
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for details.
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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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Notes
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-----
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The driver uses the default resolution settings of 12 bit for humidity and 14
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bit for temperature, which results in typical measurement times of 11 ms for
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humidity and 44 ms for temperature. To keep self heating below 0.1 degree
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Celsius, the device should not be active for more than 10% of the time. For
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this reason, the driver performs no more than two measurements per second and
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reports cached information if polled more frequently.
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Different resolutions, the on-chip heater, using the CRC checksum and reading
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the serial number are not supported yet.
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