0001 Kernel driver sht21
0002 ===================
0003
0004 Supported chips:
0005
0006 * Sensirion SHT21
0007
0008 Prefix: 'sht21'
0009
0010 Addresses scanned: none
0011
0012 Datasheet: Publicly available at the Sensirion website
0013
0014 https://www.sensirion.com/file/datasheet_sht21
0015
0016
0017
0018 * Sensirion SHT25
0019
0020 Prefix: 'sht25'
0021
0022 Addresses scanned: none
0023
0024 Datasheet: Publicly available at the Sensirion website
0025
0026 https://www.sensirion.com/file/datasheet_sht25
0027
0028
0029
0030 Author:
0031
0032 Urs Fleisch <urs.fleisch@sensirion.com>
0033
0034 Description
0035 -----------
0036
0037 The SHT21 and SHT25 are humidity and temperature sensors in a DFN package of
0038 only 3 x 3 mm footprint and 1.1 mm height. The difference between the two
0039 devices is the higher level of precision of the SHT25 (1.8% relative humidity,
0040 0.2 degree Celsius) compared with the SHT21 (2.0% relative humidity,
0041 0.3 degree Celsius).
0042
0043 The devices communicate with the I2C protocol. All sensors are set to the same
0044 I2C address 0x40, so an entry with I2C_BOARD_INFO("sht21", 0x40) can be used
0045 in the board setup code.
0046
0047 sysfs-Interface
0048 ---------------
0049
0050 temp1_input
0051 - temperature input
0052
0053 humidity1_input
0054 - humidity input
0055 eic
0056 - Electronic Identification Code
0057
0058 Notes
0059 -----
0060
0061 The driver uses the default resolution settings of 12 bit for humidity and 14
0062 bit for temperature, which results in typical measurement times of 22 ms for
0063 humidity and 66 ms for temperature. To keep self heating below 0.1 degree
0064 Celsius, the device should not be active for more than 10% of the time,
0065 e.g. maximum two measurements per second at the given resolution.
0066
0067 Different resolutions, the on-chip heater, and using the CRC checksum
0068 are not supported yet.
