mirror of
https://github.com/RobTillaart/Arduino.git
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144 lines
2.0 KiB
C++
144 lines
2.0 KiB
C++
//
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// FILE: DHT12.cpp
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// AUTHOR: Rob Tillaart
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// VERSION: 0.5.0
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// PURPOSE: Arduino library for I2C DHT12 temperature and humidity sensor.
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// URL: https://github.com/RobTillaart/DHT12
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#include "DHT12.h"
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// fixed address
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#define DHT12_ADDRESS ((uint8_t)0x5C)
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DHT12::DHT12(TwoWire *wire)
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{
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_wire = wire;
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_temperature = 0;
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_humidity = 0;
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_humOffset = 0;
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_tempOffset = 0;
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_lastRead = 0;
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}
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bool DHT12::begin()
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{
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return isConnected();
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}
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bool DHT12::isConnected()
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{
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_wire->beginTransmission(DHT12_ADDRESS);
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int rv = _wire->endTransmission();
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return rv == 0;
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}
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int8_t DHT12::read()
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{
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// READ SENSOR
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int status = _readSensor();
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if (status < 0) return status;
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// CONVERT AND STORE
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_humidity = _bits[0] + _bits[1] * 0.1;
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_temperature = _bits[2] + (_bits[3] & 0x7F) * 0.1;
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if (_bits[3] & 0x80)
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{
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_temperature = -_temperature;
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}
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// TEST CHECKSUM
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uint8_t checksum = _bits[0] + _bits[1] + _bits[2] + _bits[3];
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if (_bits[4] != checksum)
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{
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return DHT12_ERROR_CHECKSUM;
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}
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_lastRead = millis();
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return DHT12_OK;
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}
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float DHT12::getHumidity()
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{
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return _humidity + _humOffset;
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}
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float DHT12::getTemperature()
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{
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return _temperature + _tempOffset;
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}
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void DHT12::setHumOffset(float offset)
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{
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_humOffset = offset;
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}
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void DHT12::setTempOffset(float offset)
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{
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_tempOffset = offset;
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}
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float DHT12::getHumOffset()
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{
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return _humOffset;
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}
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float DHT12::getTempOffset()
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{
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return _tempOffset;
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}
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uint32_t DHT12::lastRead()
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{
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return _lastRead;
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}
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int DHT12::_readSensor()
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{
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// GET CONNECTION
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_wire->beginTransmission(DHT12_ADDRESS);
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_wire->write(0);
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int rv = _wire->endTransmission();
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if (rv < 0)
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{
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return rv;
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}
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// GET DATA
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const uint8_t length = 5;
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int bytes = _wire->requestFrom(DHT12_ADDRESS, length);
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if (bytes == 0)
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{
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return DHT12_ERROR_CONNECT;
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}
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if (bytes < length)
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{
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return DHT12_MISSING_BYTES;
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}
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for (int i = 0; i < bytes; i++)
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{
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_bits[i] = _wire->read();
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}
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return bytes;
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}
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// -- END OF FILE --
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