| 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. |