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68 lines
1.6 KiB
68 lines
1.6 KiB
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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https://www.sensirion.com/file/datasheet_sht21 |
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* Sensirion SHT25 |
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Prefix: 'sht25' |
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Addresses scanned: none |
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Datasheet: Publicly available at the Sensirion website |
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https://www.sensirion.com/file/datasheet_sht25 |
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Author: |
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Urs Fleisch <[email protected]> |
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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 |
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- temperature input |
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humidity1_input |
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- humidity input |
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eic |
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- Electronic Identification Code |
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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, and using the CRC checksum |
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are not supported yet.
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