mirror of
https://github.com/RobTillaart/Arduino.git
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165 lines
3.4 KiB
C++
165 lines
3.4 KiB
C++
//
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// FILE: dhtnew.cpp
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// AUTHOR: Rob.Tillaart@gmail.com
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// VERSION: 0.1.4
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// PURPOSE: New DHT Temperature & Humidity Sensor library for Arduino
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// URL:
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//
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// HISTORY:
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// 0.1.0 2017-07-24 initial version based upon DHTStable
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// 0.1.1 2017-07-29 add begin() to determine type once and for all instead of every call + refactor
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// 0.1.2 2018-01-08 improved begin() + refactor()
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// 0.1.3 2018-01-08 removed begin() + moved detection to read() function
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// 0.1.4 2018-04-03 add get-/setDisableIRQ(bool b)
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//
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// Released to the public domain
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//
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#include "dhtnew.h"
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/////////////////////////////////////////////////////
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//
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// PUBLIC
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//
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DHTNEW::DHTNEW(uint8_t pin) { _pin = pin; };
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// return values:
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// DHTLIB_OK
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// DHTLIB_ERROR_CHECKSUM
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// DHTLIB_ERROR_TIMEOUT
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int DHTNEW::read()
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{
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if (_type != 0) return _read();
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_type = 22;
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_wakeupDelay = DHTLIB_DHT_WAKEUP;
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int rv = _read();
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if (rv == DHTLIB_OK) return rv;
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_type = 11;
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_wakeupDelay = DHTLIB_DHT11_WAKEUP;
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rv = _read();
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if (rv == DHTLIB_OK) return rv;
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_type = 0; // retry next time
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return rv;
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}
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// return values:
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// DHTLIB_OK
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// DHTLIB_ERROR_CHECKSUM
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// DHTLIB_ERROR_TIMEOUT
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int DHTNEW::_read()
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{
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_lastRead = millis();
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// READ VALUES
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if (_disableIRQ) noInterrupts();
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int rv = _readSensor();
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if (_disableIRQ) interrupts();
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if (rv != DHTLIB_OK)
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{
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humidity = DHTLIB_INVALID_VALUE;
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temperature = DHTLIB_INVALID_VALUE;
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return rv; // propagate error value
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}
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if (_type == 22) // DHT22, DHT33, DHT44, compatible
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{
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humidity = (_bits[0] * 256 + _bits[1]) * 0.1;
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temperature = (_bits[2] * 256 + _bits[3]) * 0.1;
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}
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else // if (_type == 11) // DHT11, DH12, compatible
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{
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humidity = _bits[0] + _bits[1] * 0.1;
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temperature = _bits[2] + _bits[3] * 0.1;
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}
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if (_bits[2] & 0x80) // negative temperature
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{
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temperature = -temperature;
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}
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humidity += _humOffset; // check overflow ???
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temperature += _tempOffset;
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// TEST CHECKSUM
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uint8_t sum = _bits[0] + _bits[1] + _bits[2] + _bits[3];
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if (_bits[4] != sum)
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{
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return DHTLIB_ERROR_CHECKSUM;
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}
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return DHTLIB_OK;
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}
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/////////////////////////////////////////////////////
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//
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// PRIVATE
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//
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// return values:
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// DHTLIB_OK
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// DHTLIB_ERROR_TIMEOUT
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int DHTNEW::_readSensor()
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{
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// INIT BUFFERVAR TO RECEIVE DATA
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uint8_t mask = 128;
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uint8_t idx = 0;
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// EMPTY BUFFER
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for (uint8_t i = 0; i < 5; i++) _bits[i] = 0;
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// REQUEST SAMPLE
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pinMode(_pin, OUTPUT);
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digitalWrite(_pin, LOW);
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delay(_wakeupDelay);
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pinMode(_pin, INPUT);
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delayMicroseconds(40);
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// GET ACKNOWLEDGE or TIMEOUT
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uint16_t loopCnt = DHTLIB_TIMEOUT;
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while(digitalRead(_pin) == LOW)
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{
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if (--loopCnt == 0) return DHTLIB_ERROR_TIMEOUT;
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}
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loopCnt = DHTLIB_TIMEOUT;
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while(digitalRead(_pin) == HIGH)
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{
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if (--loopCnt == 0) return DHTLIB_ERROR_TIMEOUT;
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}
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// READ THE OUTPUT - 40 BITS => 5 BYTES
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for (uint8_t i = 40; i != 0; i--)
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{
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loopCnt = DHTLIB_TIMEOUT;
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while(digitalRead(_pin) == LOW)
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{
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if (--loopCnt == 0) return DHTLIB_ERROR_TIMEOUT;
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}
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uint32_t t = micros();
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loopCnt = DHTLIB_TIMEOUT;
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while(digitalRead(_pin) == HIGH)
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{
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if (--loopCnt == 0) return DHTLIB_ERROR_TIMEOUT;
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}
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if ((micros() - t) > 40)
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{
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_bits[idx] |= mask;
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}
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mask >>= 1;
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if (mask == 0) // next byte?
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{
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mask = 128;
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idx++;
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}
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}
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return DHTLIB_OK;
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}
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//
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// END OF FILE
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//
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