| 1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768 |
- Kernel driver sht21
- ===================
- Supported chips:
- * Sensirion SHT21
- Prefix: 'sht21'
- Addresses scanned: none
- Datasheet: Publicly available at the Sensirion website
- https://www.sensirion.com/file/datasheet_sht21
- * Sensirion SHT25
- Prefix: 'sht25'
- Addresses scanned: none
- Datasheet: Publicly available at the Sensirion website
- https://www.sensirion.com/file/datasheet_sht25
- Author:
- Urs Fleisch <[email protected]>
- 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
- eic
- - Electronic Identification Code
- 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, and using the CRC checksum
- are not supported yet.
|
