72 lines
2.6 KiB
C++
72 lines
2.6 KiB
C++
/*
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main.cpp - SHT21 Sensor Library
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Copyright (c) 2019, Stefan Brand
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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1. Redistributions of source code must retain the above copyright notice, this
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list of conditions and the following disclaimer.
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2. Redistributions in binary form must reproduce the above copyright notice,
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this list of conditions and the following disclaimer in the documentation
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and/or other materials provided with the distribution.
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3. Neither the name of the copyright holder nor the names of its
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contributors may be used to endorse or promote products derived from
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this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <Arduino.h>
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#include <i2cmaster.h>
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#include <inttypes.h>
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#include "SHT21.h"
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SHT21::SHT21() {
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// Initialize I2C Bus
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i2c_init();
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}
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uint16_t SHT21::sensorRead(uint8_t command) {
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uint16_t result;
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// Trigger Measurement
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i2c_start_wait(SHT21_I2CADDR+I2C_WRITE);
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i2c_write(command);
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//if (command == SHT21_TEMPHOLD || command == SHT21_TEMPNOHOLD) {
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delay(86); // Max Measurement Time 14 bit Temperature
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//} else if (command == SHT21_HUMIHOLD || command == SHT21_HUMINOHOLD) {
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// delay(30); // Max Measurement Time 12 bit Humidity
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//}
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i2c_stop();
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// Read Value
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i2c_start_wait(SHT21_I2CADDR+I2C_READ);
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result = (i2c_readAck() << 8);
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result |= (i2c_readNak());
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i2c_stop();
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result &= ~0x0003; // Clear CRC Bits
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return result;
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}
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float SHT21::getTemperature(void) {
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return (-46.85 + 175.72 / 65536.0 * (float)(sensorRead(SHT21_TEMPHOLD)));
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}
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float SHT21::getHumidity(void) {
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return (-6.0 + 125.0 / 65536.0 * (float)(sensorRead(SHT21_HUMIHOLD)));
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} |