| 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. |
