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Diffstat (limited to 'kernel/Documentation/hwmon/htu21')
| -rw-r--r-- | kernel/Documentation/hwmon/htu21 | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/kernel/Documentation/hwmon/htu21 b/kernel/Documentation/hwmon/htu21 new file mode 100644 index 000000000..f39a215fb --- /dev/null +++ b/kernel/Documentation/hwmon/htu21 @@ -0,0 +1,46 @@ +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. |