100 lines
2.2 KiB
C++
100 lines
2.2 KiB
C++
/***************************************************
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This is a library for the HTU21DF Humidity & Temp Sensor
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Designed specifically to work with the HTU21DF sensor from Adafruit
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----> https://www.adafruit.com/products/1899
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These displays use I2C to communicate, 2 pins are required to
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interface
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Adafruit invests time and resources providing this open source code,
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please support Adafruit and open-source hardware by purchasing
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products from Adafruit!
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Written by Limor Fried/Ladyada for Adafruit Industries.
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BSD license, all text above must be included in any redistribution
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****************************************************/
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#include "Adafruit_HTU21DF.h"
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#if defined(__AVR__)
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#include <util/delay.h>
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#endif
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Adafruit_HTU21DF::Adafruit_HTU21DF() {
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}
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boolean Adafruit_HTU21DF::begin(void) {
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Wire.begin();
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reset();
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Wire.beginTransmission(HTU21DF_I2CADDR);
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Wire.write(HTU21DF_READREG);
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Wire.endTransmission();
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Wire.requestFrom(HTU21DF_I2CADDR, 1);
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return (Wire.read() == 0x2); // after reset should be 0x2
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}
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void Adafruit_HTU21DF::reset(void) {
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Wire.beginTransmission(HTU21DF_I2CADDR);
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Wire.write(HTU21DF_RESET);
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Wire.endTransmission();
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delay(15);
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}
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float Adafruit_HTU21DF::readTemperature(void) {
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// OK lets ready!
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Wire.beginTransmission(HTU21DF_I2CADDR);
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Wire.write(HTU21DF_READTEMP);
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Wire.endTransmission();
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delay(50); // add delay between request and actual read!
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Wire.requestFrom(HTU21DF_I2CADDR, 3);
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while (!Wire.available()) {}
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uint16_t t = Wire.read();
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t <<= 8;
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t |= Wire.read();
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uint8_t crc = Wire.read();
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float temp = t;
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temp *= 175.72;
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temp /= 65536;
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temp -= 46.85;
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return temp;
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}
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float Adafruit_HTU21DF::readHumidity(void) {
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// OK lets ready!
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Wire.beginTransmission(HTU21DF_I2CADDR);
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Wire.write(HTU21DF_READHUM);
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Wire.endTransmission();
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delay(50); // add delay between request and actual read!
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Wire.requestFrom(HTU21DF_I2CADDR, 3);
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while (!Wire.available()) {}
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uint16_t h = Wire.read();
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h <<= 8;
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h |= Wire.read();
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uint8_t crc = Wire.read();
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float hum = h;
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hum *= 125;
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hum /= 65536;
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hum -= 6;
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return hum;
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}
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/*********************************************************************/
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