mirror of
https://github.com/RobTillaart/Arduino.git
synced 2024-09-19 16:46:11 -04:00
179 lines
3.5 KiB
C++
179 lines
3.5 KiB
C++
//
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// FILE: DHTStable.cpp
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// AUTHOR: Rob Tillaart
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// VERSION: 1.1.2
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// PURPOSE: DHT Temperature & Humidity Sensor library for Arduino
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// URL: https://github.com/RobTillaart/DHTstable
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//
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// HISTORY: see CHANGELOG.md
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#include "DHTStable.h"
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/////////////////////////////////////////////////////
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//
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// PUBLIC
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//
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DHTStable::DHTStable()
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{
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reset();
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}
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void DHTStable::reset()
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{
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_temperature = 0.0;
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_humidity = 0.0;
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_disableIRQ = false;
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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 DHTStable::read11(uint8_t pin)
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{
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// READ VALUES
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if (_disableIRQ) noInterrupts();
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int rv = _readSensor(pin, DHTLIB_DHT11_WAKEUP);
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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; // invalid value, or is NaN prefered?
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_temperature = DHTLIB_INVALID_VALUE; // invalid value
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return rv;
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}
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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] & 0x7F) + _bits[3] * 0.1;
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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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// 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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// 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 DHTStable::read(uint8_t pin)
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{
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// READ VALUES
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if (_disableIRQ) noInterrupts();
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int rv = _readSensor(pin, DHTLIB_DHT_WAKEUP);
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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; // NaN preferred?
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_temperature = DHTLIB_INVALID_VALUE; // NaN preferred?
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return rv; // propagate error value
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}
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// CONVERT AND STORE
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_humidity = word(_bits[0], _bits[1]) * 0.1;
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int16_t t = ((_bits[2] & 0x7F) * 256 + _bits[3]);
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if (t == 0)
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{
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_temperature = 0.0; // prevent -0.0;
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}
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else
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{
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_temperature = t * 0.1;
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if((_bits[2] & 0x80) == 0x80 )
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{
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_temperature = -_temperature;
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}
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}
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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 DHTStable::_readSensor(uint8_t pin, uint8_t wakeupDelay)
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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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// -- END OF FILE --
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