summaryrefslogtreecommitdiff
path: root/Documentation/hwmon/sht21
diff options
context:
space:
mode:
authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /Documentation/hwmon/sht21
Initial import
Diffstat (limited to 'Documentation/hwmon/sht21')
-rw-r--r--Documentation/hwmon/sht2149
1 files changed, 49 insertions, 0 deletions
diff --git a/Documentation/hwmon/sht21 b/Documentation/hwmon/sht21
new file mode 100644
index 000000000..db17fda45
--- /dev/null
+++ b/Documentation/hwmon/sht21
@@ -0,0 +1,49 @@
+Kernel driver sht21
+===================
+
+Supported chips:
+ * Sensirion SHT21
+ Prefix: 'sht21'
+ Addresses scanned: none
+ Datasheet: Publicly available at the Sensirion website
+ http://www.sensirion.com/en/pdf/product_information/Datasheet-humidity-sensor-SHT21.pdf
+
+ * Sensirion SHT25
+ Prefix: 'sht21'
+ Addresses scanned: none
+ Datasheet: Publicly available at the Sensirion website
+ http://www.sensirion.com/en/pdf/product_information/Datasheet-humidity-sensor-SHT25.pdf
+
+Author:
+ Urs Fleisch <urs.fleisch@sensirion.com>
+
+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
+
+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, using the CRC checksum and reading
+the serial number are not supported yet.