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authorYunhong Jiang <yunhong.jiang@intel.com>2015-08-04 12:17:53 -0700
committerYunhong Jiang <yunhong.jiang@intel.com>2015-08-04 15:44:42 -0700
commit9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (patch)
tree1c9cafbcd35f783a87880a10f85d1a060db1a563 /kernel/Documentation/hwmon/htu21
parent98260f3884f4a202f9ca5eabed40b1354c489b29 (diff)
Add the rt linux 4.1.3-rt3 as base
Import the rt linux 4.1.3-rt3 as OPNFV kvm base. It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and the base is: commit 0917f823c59692d751951bf5ea699a2d1e2f26a2 Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Date: Sat Jul 25 12:13:34 2015 +0200 Prepare v4.1.3-rt3 Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> We lose all the git history this way and it's not good. We should apply another opnfv project repo in future. Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423 Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>
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+Kernel driver htu21
+===================
+
+Supported chips:
+ * Measurement Specialties HTU21D
+ Prefix: 'htu21'
+ Addresses scanned: none
+ Datasheet: Publicly available at the Measurement Specialties website
+ http://www.meas-spec.com/downloads/HTU21D.pdf
+
+
+Author:
+ William Markezana <william.markezana@meas-spec.com>
+
+Description
+-----------
+
+The HTU21D is a humidity and temperature sensor in a DFN package of
+only 3 x 3 mm footprint and 0.9 mm height.
+
+The devices communicate with the I2C protocol. All sensors are set to the
+same I2C address 0x40, so an entry with I2C_BOARD_INFO("htu21", 0x40) can
+be used in the board setup code.
+
+This driver does not auto-detect devices. You will have to instantiate the
+devices explicitly. Please see Documentation/i2c/instantiating-devices
+for details.
+
+sysfs-Interface
+---------------
+
+temp1_input - temperature input
+humidity1_input - humidity input
+
+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 11 ms for
+humidity and 44 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. For
+this reason, the driver performs no more than two measurements per second and
+reports cached information if polled more frequently.
+
+Different resolutions, the on-chip heater, using the CRC checksum and reading
+the serial number are not supported yet.