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1Kernel driver htu21
2===================
3
4Supported chips:
5 * Measurement Specialties HTU21D
6 Prefix: 'htu21'
7 Addresses scanned: none
8 Datasheet: Publicly available at the Measurement Specialties website
9 http://www.meas-spec.com/downloads/HTU21D.pdf
10
11
12Author:
13 William Markezana <william.markezana@meas-spec.com>
14
15Description
16-----------
17
18The HTU21D is a humidity and temperature sensor in a DFN package of
19only 3 x 3 mm footprint and 0.9 mm height.
20
21The devices communicate with the I2C protocol. All sensors are set to the
22same I2C address 0x40, so an entry with I2C_BOARD_INFO("htu21", 0x40) can
23be used in the board setup code.
24
25This driver does not auto-detect devices. You will have to instantiate the
26devices explicitly. Please see Documentation/i2c/instantiating-devices
27for details.
28
29sysfs-Interface
30---------------
31
32temp1_input - temperature input
33humidity1_input - humidity input
34
35Notes
36-----
37
38The driver uses the default resolution settings of 12 bit for humidity and 14
39bit for temperature, which results in typical measurement times of 11 ms for
40humidity and 44 ms for temperature. To keep self heating below 0.1 degree
41Celsius, the device should not be active for more than 10% of the time. For
42this reason, the driver performs no more than two measurements per second and
43reports cached information if polled more frequently.
44
45Different resolutions, the on-chip heater, using the CRC checksum and reading
46the serial number are not supported yet.