98 lines
3.3 KiB
C++
98 lines
3.3 KiB
C++
// I2Cdev library collection - HTU21D I2C device class header file
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// Based on MEAS HTU21D HPC199_2 HTU321(F) datasheet, October 2013
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// 2016-03-24 by https://github.com/eadf
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// Updates should (hopefully) always be available at https://github.com/jrowberg/i2cdevlib
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//
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// Changelog:
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// 2016-03-24 - initial release
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/* ============================================
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I2Cdev device library code is placed under the MIT license
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Copyright (c) 2016 Eadf, Jeff Rowberg
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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===============================================
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*/
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#include "HTU21D.h"
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/** Default constructor, uses default I2C address.
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* @see HTU21D_DEFAULT_ADDRESS
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*/
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HTU21D::HTU21D() {
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devAddr = HTU21D_DEFAULT_ADDRESS;
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}
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/** Power on and prepare for general usage.
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* This operation calls reset() on the HTU21D device and it takes at least 15milliseconds.
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*/
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void HTU21D::initialize() {
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reset();
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}
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/** Verify the I2C connection.
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* Make sure the device is connected and responds as expected.
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* This operation calls reset() on the HTU21D device and it takes at least 15milliseconds.
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* @return True if connection is valid, false otherwise
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*/
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bool HTU21D::testConnection() {
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reset();
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buffer[0] = 0;
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I2Cdev::readByte(devAddr, HTU21D_READ_USER_REGISTER, buffer);
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return buffer[0] == 0x2;
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}
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/** Reads and returns the temperature, ignores the CRC field.
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* @return The measured temperature, or NaN if the operation failed.
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*/
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float HTU21D::getTemperature() {
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// Ignore the CRC byte
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uint16_t t = 0;
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if (1!=I2Cdev::readWord(devAddr, HTU21D_RA_TEMPERATURE, &t)){
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return NAN;
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}
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// clear the status bits (bit0 & bit1) and calculate the temperature
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// as per the formula in the datasheet
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return ((float)(t&0xFFFC))*175.72/65536.0-46.85;
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}
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/** Reads and returns the humidity, ignores the CRC field
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* @return The measured humidity, or NaN if the operation failed.
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*/
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float HTU21D::getHumidity() {
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// Ignore the CRC byte
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uint16_t t = 0;
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if (1!=I2Cdev::readWord(devAddr, HTU21D_RA_HUMIDITY, &t)){
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return NAN;
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}
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// clear the status bits (bit0 & bit1) and calculate the humidity
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// as per the formula in the datasheet
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return ((float)(t&0xFFFC))*125.0/65536.0-6.0;
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}
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/** Does a soft reset of the HTU21D
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* This operation takes at least 15milliseconds.
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*/
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void HTU21D::reset() {
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I2Cdev::writeByte(devAddr, HTU21D_RESET, 0);
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delay(15);
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}
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