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- Kernel driver sht21
- ===================
- Supported chips:
- * Sensirion SHT21
- Prefix: 'sht21'
- Addresses scanned: none
- Datasheet: Publicly available at the Sensirion website
- http://www.sensirion.com/en/pdf/product_information/Datasheet-humidity-sensor-SHT21.pdf
- * Sensirion SHT25
- Prefix: 'sht21'
- Addresses scanned: none
- Datasheet: Publicly available at the Sensirion website
- http://www.sensirion.com/en/pdf/product_information/Datasheet-humidity-sensor-SHT25.pdf
- Author:
- Urs Fleisch <urs.fleisch@sensirion.com>
- Description
- -----------
- The SHT21 and SHT25 are humidity and temperature sensors in a DFN package of
- only 3 x 3 mm footprint and 1.1 mm height. The difference between the two
- devices is the higher level of precision of the SHT25 (1.8% relative humidity,
- 0.2 degree Celsius) compared with the SHT21 (2.0% relative humidity,
- 0.3 degree Celsius).
- The devices communicate with the I2C protocol. All sensors are set to the same
- I2C address 0x40, so an entry with I2C_BOARD_INFO("sht21", 0x40) can be used
- in the board setup code.
- sysfs-Interface
- ---------------
- temp1_input - temperature input
- humidity1_input - humidity input
- Notes
- -----
- The driver uses the default resolution settings of 12 bit for humidity and 14
- bit for temperature, which results in typical measurement times of 22 ms for
- humidity and 66 ms for temperature. To keep self heating below 0.1 degree
- Celsius, the device should not be active for more than 10% of the time,
- e.g. maximum two measurements per second at the given resolution.
- Different resolutions, the on-chip heater, using the CRC checksum and reading
- the serial number are not supported yet.
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