arduino溫濕度傳感器DHT11, 21, 22, 33 and 44庫文件 MEGA2560芯片

ID:312559 · 發(fā)表于 2018-4-20 17:22

The DHT11, 21, 22, 33 and 44 are relative inexpensive sensors for measuring temperature and humidity.

This library can be used for reading both values from these DHT sensors.
The DHT11 only returns integers (e.g. 20) and does not support negative values.
The others are quite similar and provide one decimal digit (e.g. 20.2)
The hardware pins of the sensors and handshake are identical so ideal to combine in one lib.

The library (0.1.13 version) is confirmed to work on:

UNO (tested myself)
2009 (tested myself)
MEGA2560
DUE
attiny85 @8MHz
Digistump Digix @ 84 MHz

More information - http://playground.arduino.cc//Main/DHTLib -

Notes:
version 0.1.13 is the last stable version for both AVR and ARM

version 0.1.14 and up are not compatible anymore with pre 1.0 Arduino
version 0.1.14 and up have breaking changes wrt ARM based arduino's e.g DUE.
version 0.1.15 is stable version for AVR only
version 0.1.16 and 0.1.17 have breaking changes for DHT11
version 0.1.18 works again for DHT11 (avr only)
version 0.1.19 fixed masking bug DHT11 (avr only)
version 0.1.20 Reduce footprint (34 bytes) by using int8_t as error codes. (thanks to chaveiro)

單片機源程序如下:

//
// FILE: dht.cpp
// AUTHOR: Rob Tillaart
// VERSION: 0.1.20
// PURPOSE: DHT Temperature & Humidity Sensor library for Arduino
// URL: http://arduino.cc/playground/Main/DHTLib
//
// HISTORY:
// 0.1.20 Reduce footprint (34 bytes) by using int8_t as error codes.
// (thanks to chaveiro)
// 0.1.19 masking error for DHT11 - FIXED (thanks Richard for noticing)
// 0.1.18 version 1.16/17 broke the DHT11 - FIXED
// 0.1.17 replaced micros() with adaptive loopcount
// removed DHTLIB_INVALID_VALUE
// added DHTLIB_ERROR_CONNECT
// added DHTLIB_ERROR_ACK_L DHTLIB_ERROR_ACK_H
// 0.1.16 masking unused bits (less errors); refactored bits[]
// 0.1.15 reduced # micros calls 2->1 in inner loop.
// 0.1.14 replace digital read with faster (~3x) code
// => more robust low MHz machines.
//
// 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)
// 0.1.00 by Rob Tillaart (01/04/2011)
//
// inspired by DHT11 library
//
// Released to the public domain
//
#include "dht.h"
/////////////////////////////////////////////////////
//
// PUBLIC
//
int8_t dht::read11(uint8_t pin)
{
// READ VALUES
int8_t result = _readSensor(pin, DHTLIB_DHT11_WAKEUP, DHTLIB_DHT11_LEADING_ZEROS);
// these bits are always zero, masking them reduces errors.
bits[0] &= 0x7F;
bits[2] &= 0x7F;
// CONVERT AND STORE
humidity = bits[0]; // bits[1] == 0;
temperature = bits[2]; // bits[3] == 0;
// TEST CHECKSUM
// bits[1] && bits[3] both 0
uint8_t sum = bits[0] + bits[2];
if (bits[4] != sum)
{
return DHTLIB_ERROR_CHECKSUM;
}
return result;
}
int8_t dht::read(uint8_t pin)
{
// READ VALUES
int8_t result = _readSensor(pin, DHTLIB_DHT_WAKEUP, DHTLIB_DHT_LEADING_ZEROS);
// these bits are always zero, masking them reduces errors.
bits[0] &= 0x03;
bits[2] &= 0x83;
// 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 result;
}
/////////////////////////////////////////////////////
//
// PRIVATE
//
int8_t dht::_readSensor(uint8_t pin, uint8_t wakeupDelay, uint8_t leadingZeroBits)
{
// INIT BUFFERVAR TO RECEIVE DATA
uint8_t mask = 128;
uint8_t idx = 0;
uint8_t data = 0;
uint8_t state = LOW;
uint8_t pstate = LOW;
uint16_t zeroLoop = DHTLIB_TIMEOUT;
uint16_t delta = 0;
leadingZeroBits = 40 - leadingZeroBits; // reverse counting...
// replace digitalRead() with Direct Port Reads.
// reduces footprint ~100 bytes => portability issue?
// direct port read is about 3x faster
uint8_t bit = digitalPinToBitMask(pin);
uint8_t port = digitalPinToPort(pin);
volatile uint8_t *PIR = portInputRegister(port);
// REQUEST SAMPLE
pinMode(pin, OUTPUT);
digitalWrite(pin, LOW); // T-be
delay(wakeupDelay);
digitalWrite(pin, HIGH); // T-go
pinMode(pin, INPUT);
uint16_t loopCount = DHTLIB_TIMEOUT * 2; // 200uSec max
// while(digitalRead(pin) == HIGH)
while ((*PIR & bit) != LOW )
{
if (--loopCount == 0) return DHTLIB_ERROR_CONNECT;
}
// GET ACKNOWLEDGE or TIMEOUT
loopCount = DHTLIB_TIMEOUT;
// while(digitalRead(pin) == LOW)
while ((*PIR & bit) == LOW ) // T-rel
{
if (--loopCount == 0) return DHTLIB_ERROR_ACK_L;
}
loopCount = DHTLIB_TIMEOUT;
// while(digitalRead(pin) == HIGH)
while ((*PIR & bit) != LOW ) // T-reh
{
if (--loopCount == 0) return DHTLIB_ERROR_ACK_H;
}
loopCount = DHTLIB_TIMEOUT;
// READ THE OUTPUT - 40 BITS => 5 BYTES
for (uint8_t i = 40; i != 0; )
{
// WAIT FOR FALLING EDGE
state = (*PIR & bit);
if (state == LOW && pstate != LOW)
{
if (i > leadingZeroBits) // DHT22 first 6 bits are all zero !! DHT11 only 1
{
zeroLoop = min(zeroLoop, loopCount);
delta = (DHTLIB_TIMEOUT - zeroLoop)/4;
}
else if ( loopCount <= (zeroLoop - delta) ) // long -> one
{
data |= mask;
}
mask >>= 1;
if (mask == 0) // next byte
{
mask = 128;
bits[idx] = data;
idx++;
data = 0;
}
// next bit
--i;
// reset timeout flag
loopCount = DHTLIB_TIMEOUT;
}
pstate = state;
// Check timeout
if (--loopCount == 0)
{
return DHTLIB_ERROR_TIMEOUT;
}
}
pinMode(pin, OUTPUT);
digitalWrite(pin, HIGH);
return DHTLIB_OK;
}
//
// END OF FILE
//

復制代碼

全部資料51hei下載地址：

DHT-lib.zip (10.73 KB, 下載次數: 31)

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