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review.shift-gmbh.com / SHIFTPHONES / mainline / linux / 633a8e8986eac2c9e32c76ccb9cfe0e5a898b314 / . / Documentation / hwmon / sht21.rst
blob: 1bccc8e8aac8d3532ec17dcdbc6a172102877085 [file] [log] [blame]
Urs Fleisch430400b2011-01-07 07:15:39 +0000[diff] [blame]1Kernel driver sht21
2===================
3
4Supported chips:
Mauro Carvalho Chehabb04f2f72019-04-17 06:46:28 -0300[diff] [blame]5
Urs Fleisch430400b2011-01-07 07:15:39 +0000[diff] [blame]6 * Sensirion SHT21
Mauro Carvalho Chehabb04f2f72019-04-17 06:46:28 -0300[diff] [blame]7
Urs Fleisch430400b2011-01-07 07:15:39 +0000[diff] [blame]8 Prefix: 'sht21'
Mauro Carvalho Chehabb04f2f72019-04-17 06:46:28 -0300[diff] [blame]9
Urs Fleisch430400b2011-01-07 07:15:39 +0000[diff] [blame]10 Addresses scanned: none
Mauro Carvalho Chehabb04f2f72019-04-17 06:46:28 -0300[diff] [blame]11
Urs Fleisch430400b2011-01-07 07:15:39 +0000[diff] [blame]12 Datasheet: Publicly available at the Sensirion website
Mauro Carvalho Chehabb04f2f72019-04-17 06:46:28 -0300[diff] [blame]13
Alexander A. Klimovad736c12020-07-19 19:55:12 +0200[diff] [blame]14 https://www.sensirion.com/file/datasheet_sht21
Urs Fleisch430400b2011-01-07 07:15:39 +0000[diff] [blame]15
Mauro Carvalho Chehabb04f2f72019-04-17 06:46:28 -0300[diff] [blame]16
17
Urs Fleisch430400b2011-01-07 07:15:39 +0000[diff] [blame]18 * Sensirion SHT25
Mauro Carvalho Chehabb04f2f72019-04-17 06:46:28 -0300[diff] [blame]19
Danilo Bargen8e1d6fe2018-02-02 11:40:52 +0100[diff] [blame]20 Prefix: 'sht25'
Mauro Carvalho Chehabb04f2f72019-04-17 06:46:28 -0300[diff] [blame]21
Urs Fleisch430400b2011-01-07 07:15:39 +0000[diff] [blame]22 Addresses scanned: none
Mauro Carvalho Chehabb04f2f72019-04-17 06:46:28 -0300[diff] [blame]23
Urs Fleisch430400b2011-01-07 07:15:39 +0000[diff] [blame]24 Datasheet: Publicly available at the Sensirion website
Mauro Carvalho Chehabb04f2f72019-04-17 06:46:28 -0300[diff] [blame]25
Alexander A. Klimovad736c12020-07-19 19:55:12 +0200[diff] [blame]26 https://www.sensirion.com/file/datasheet_sht25
Urs Fleisch430400b2011-01-07 07:15:39 +0000[diff] [blame]27
Mauro Carvalho Chehabb04f2f72019-04-17 06:46:28 -0300[diff] [blame]28
29
Urs Fleisch430400b2011-01-07 07:15:39 +0000[diff] [blame]30Author:
Mauro Carvalho Chehabb04f2f72019-04-17 06:46:28 -0300[diff] [blame]31
Urs Fleisch430400b2011-01-07 07:15:39 +0000[diff] [blame]32 Urs Fleisch <urs.fleisch@sensirion.com>
33
34Description
35-----------
36
37The SHT21 and SHT25 are humidity and temperature sensors in a DFN package of
38only 3 x 3 mm footprint and 1.1 mm height. The difference between the two
39devices is the higher level of precision of the SHT25 (1.8% relative humidity,
400.2 degree Celsius) compared with the SHT21 (2.0% relative humidity,
410.3 degree Celsius).
42
43The devices communicate with the I2C protocol. All sensors are set to the same
44I2C address 0x40, so an entry with I2C_BOARD_INFO("sht21", 0x40) can be used
45in the board setup code.
46
47sysfs-Interface
48---------------
49
Mauro Carvalho Chehabb04f2f72019-04-17 06:46:28 -0300[diff] [blame]50temp1_input
51 - temperature input
52
53humidity1_input
54 - humidity input
55eic
56 - Electronic Identification Code
Urs Fleisch430400b2011-01-07 07:15:39 +0000[diff] [blame]57
58Notes
59-----
60
61The driver uses the default resolution settings of 12 bit for humidity and 14
62bit for temperature, which results in typical measurement times of 22 ms for
63humidity and 66 ms for temperature. To keep self heating below 0.1 degree
64Celsius, the device should not be active for more than 10% of the time,
65e.g. maximum two measurements per second at the given resolution.
66
Peter A. Bigot53e678d2016-12-24 07:22:44 -0600[diff] [blame]67Different resolutions, the on-chip heater, and using the CRC checksum
68are not supported yet.