ST_Anything/Arduino/libraries/DHT/dht.cpp at master · DanielOgorchock/ST_Anything · GitHub

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// FILE: dht.cpp

// AUTHOR: Rob Tillaart

// VERSION: 0.2.0

// PURPOSE: DHT Temperature & Humidity Sensor library for Arduino

// URL: https://github.com/RobTillaart/Arduino/tree/master/libraries/DHTstable

// HISTORY:

// 0.2.1 2017-09-20 fix https://github.com/RobTillaart/Arduino/issues/80

// 0.2.0 2017-07-24 fix https://github.com/RobTillaart/Arduino/issues/31 + 33

// 0.1.13 fix negative temperature

// 0.1.12 support DHT33 and DHT44 initial version

// 0.1.11 renamed DHTLIB_TIMEOUT

// 0.1.10 optimized faster WAKEUP + TIMEOUT

// 0.1.09 optimize size: timeout check + use of mask

// 0.1.08 added formula for timeout based upon clockspeed

// 0.1.07 added support for DHT21

// 0.1.06 minimize footprint (2012-12-27)

// 0.1.05 fixed negative temperature bug (thanks to Roseman)

// 0.1.04 improved readability of code using DHTLIB_OK in code

// 0.1.03 added error values for temp and humidity when read failed

// 0.1.02 added error codes

// 0.1.01 added support for Arduino 1.0, fixed typos (31/12/2011)

// 0.1.0 by Rob Tillaart (01/04/2011)

// inspired by DHT11 library

// Released to the public domain

#include "dht.h"

/////////////////////////////////////////////////////

// PUBLIC

// return values:

// DHTLIB_OK

// DHTLIB_ERROR_CHECKSUM

// DHTLIB_ERROR_TIMEOUT

int dht::read11(uint8_t pin)

{

// READ VALUES

int rv = _readSensor(pin, DHTLIB_DHT11_WAKEUP);

if (rv != DHTLIB_OK)

{

humidity = DHTLIB_INVALID_VALUE; // invalid value, or is NaN prefered?

temperature = DHTLIB_INVALID_VALUE; // invalid value

return rv;

}

// CONVERT AND STORE

humidity = bits[0]; // bits[1] == 0;

temperature = bits[2]; // bits[3] == 0;

// TEST CHECKSUM

uint8_t sum = bits[0] + bits[1] + bits[2] + bits[3];

if (bits[4] != sum)

{

return DHTLIB_ERROR_CHECKSUM;

}

return DHTLIB_OK;

}

// return values:

// DHTLIB_OK

// DHTLIB_ERROR_CHECKSUM

// DHTLIB_ERROR_TIMEOUT

int dht::read(uint8_t pin)

{

// READ VALUES

int rv = _readSensor(pin, DHTLIB_DHT_WAKEUP);

if (rv != DHTLIB_OK)

{

humidity = DHTLIB_INVALID_VALUE; // invalid value, or is NaN prefered?

temperature = DHTLIB_INVALID_VALUE; // invalid value

return rv; // propagate error value

}

// CONVERT AND STORE

humidity = word(bits[0], bits[1]) * 0.1;

temperature = word(bits[2] & 0x7F, bits[3]) * 0.1;

if (bits[2] & 0x80) // negative temperature

{

temperature = -temperature;

}

// TEST CHECKSUM

uint8_t sum = bits[0] + bits[1] + bits[2] + bits[3];

if (bits[4] != sum)

{

return DHTLIB_ERROR_CHECKSUM;

}

return DHTLIB_OK;

}

/////////////////////////////////////////////////////

// PRIVATE

// return values:

// DHTLIB_OK

// DHTLIB_ERROR_TIMEOUT

int dht::_readSensor(uint8_t pin, uint8_t wakeupDelay)

{

// INIT BUFFERVAR TO RECEIVE DATA

uint8_t mask = 128;

uint8_t idx = 0;

// EMPTY BUFFER

for (uint8_t i = 0; i < 5; i++) bits[i] = 0;

// REQUEST SAMPLE

pinMode(pin, OUTPUT);

digitalWrite(pin, LOW);

delay(wakeupDelay);

pinMode(pin, INPUT);

delayMicroseconds(40);

// GET ACKNOWLEDGE or TIMEOUT

uint16_t loopCnt = DHTLIB_TIMEOUT;

while(digitalRead(pin) == LOW)

{

if (--loopCnt == 0) return DHTLIB_ERROR_TIMEOUT;

}

loopCnt = DHTLIB_TIMEOUT;

while(digitalRead(pin) == HIGH)

{

if (--loopCnt == 0) return DHTLIB_ERROR_TIMEOUT;

}

// READ THE OUTPUT - 40 BITS => 5 BYTES

for (uint8_t i = 40; i != 0; i--)

{

loopCnt = DHTLIB_TIMEOUT;

while(digitalRead(pin) == LOW)

{

if (--loopCnt == 0) return DHTLIB_ERROR_TIMEOUT;

}

uint32_t t = micros();

loopCnt = DHTLIB_TIMEOUT;

while(digitalRead(pin) == HIGH)

{

if (--loopCnt == 0) return DHTLIB_ERROR_TIMEOUT;

}

if ((micros() - t) > 40)

{

bits[idx] |= mask;

}

mask >>= 1;

if (mask == 0) // next byte?

{

mask = 128;

idx++;

}

return DHTLIB_OK;

}

// END OF FILE

ST_Anything/Arduino/libraries/DHT/dht.cpp at master · DanielOgorchock/ST_Anything · GitHub

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