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50 lines
1.6 KiB
Plaintext
50 lines
1.6 KiB
Plaintext
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Kernel driver sht21
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===================
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Supported chips:
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* Sensirion SHT21
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Prefix: 'sht21'
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Addresses scanned: none
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Datasheet: Publicly available at the Sensirion website
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http://www.sensirion.com/en/pdf/product_information/Datasheet-humidity-sensor-SHT21.pdf
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* Sensirion SHT25
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Prefix: 'sht21'
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Addresses scanned: none
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Datasheet: Publicly available at the Sensirion website
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http://www.sensirion.com/en/pdf/product_information/Datasheet-humidity-sensor-SHT25.pdf
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Author:
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Urs Fleisch <urs.fleisch@sensirion.com>
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Description
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-----------
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The SHT21 and SHT25 are humidity and temperature sensors in a DFN package of
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only 3 x 3 mm footprint and 1.1 mm height. The difference between the two
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devices is the higher level of precision of the SHT25 (1.8% relative humidity,
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0.2 degree Celsius) compared with the SHT21 (2.0% relative humidity,
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0.3 degree Celsius).
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The devices communicate with the I2C protocol. All sensors are set to the same
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I2C address 0x40, so an entry with I2C_BOARD_INFO("sht21", 0x40) can be used
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in the board setup code.
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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 22 ms for
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humidity and 66 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,
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e.g. maximum two measurements per second at the given resolution.
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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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