DHT11 数字温湿度传感器

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（版本间的差异）
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== 概述 ==
 
== 概述 ==
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<br><br>
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== 库 ==
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<source lang=cpp>
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//
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// FILE: dht11.cpp
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// VERSION: 0.4.1
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// PURPOSE: DHT11 Temperature & Humidity Sensor library for Arduino
 +
// LICENSE: GPL v3 (http://www.gnu.org/licenses/gpl.html)
 +
//
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// DATASHEET: http://www.micro4you.com/files/sensor/DHT11.pdf
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//
 +
// HISTORY:
 +
// George Hadjikyriacou - Original version (??)
 +
// Mod by SimKard - Version 0.2 (24/11/2010)
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// Mod by Rob Tillaart - Version 0.3 (28/03/2011)
 +
// + added comments
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// + removed all non DHT11 specific code
 +
// + added references
 +
// Mod by Rob Tillaart - Version 0.4 (17/03/2012)
 +
// + added 1.0 support
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// Mod by Rob Tillaart - Version 0.4.1 (19/05/2012)
 +
// + added error codes
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//
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#include "dht11.h"
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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 dht11::read(int pin)
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{
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// BUFFER TO RECEIVE
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uint8_t bits[5];
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uint8_t cnt = 7;
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uint8_t idx = 0;
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// EMPTY BUFFER
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for (int 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(18);
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digitalWrite(pin, HIGH);
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delayMicroseconds(40);
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pinMode(pin, INPUT);
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// ACKNOWLEDGE or TIMEOUT
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unsigned int loopCnt = 10000;
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while(digitalRead(pin) == LOW)
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if (loopCnt-- == 0) return DHTLIB_ERROR_TIMEOUT;
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loopCnt = 10000;
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while(digitalRead(pin) == HIGH)
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if (loopCnt-- == 0) return DHTLIB_ERROR_TIMEOUT;
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// READ OUTPUT - 40 BITS => 5 BYTES or TIMEOUT
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for (int i=0; i<40; i++)
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{
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loopCnt = 10000;
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while(digitalRead(pin) == LOW)
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if (loopCnt-- == 0) return DHTLIB_ERROR_TIMEOUT;
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unsigned long t = micros();
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loopCnt = 10000;
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while(digitalRead(pin) == HIGH)
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if (loopCnt-- == 0) return DHTLIB_ERROR_TIMEOUT;
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if ((micros() - t) > 40) bits[idx] |= (1 << cnt);
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if (cnt == 0)  // next byte?
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{
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cnt = 7;    // restart at MSB
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idx++;      // next byte!
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}
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else cnt--;
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}
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// WRITE TO RIGHT VARS
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        // as bits[1] and bits[3] are allways zero they are omitted in formulas.
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humidity    = bits[0];
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temperature = bits[2];
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uint8_t sum = bits[0] + bits[2]; 
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if (bits[4] != sum) return DHTLIB_ERROR_CHECKSUM;
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return DHTLIB_OK;
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}
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//
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// FILE: dht11.h
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// VERSION: 0.4.1
 +
// PURPOSE: DHT11 Temperature & Humidity Sensor library for Arduino
 +
// LICENSE: GPL v3 (http://www.gnu.org/licenses/gpl.html)
 +
//
 +
// DATASHEET: http://www.micro4you.com/files/sensor/DHT11.pdf
 +
//
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// URL: http://playground.arduino.cc/Main/DHT11Lib
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//
 +
// HISTORY:
 +
// George Hadjikyriacou - Original version
 +
// see dht.cpp file
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//
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#ifndef dht11_h
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#define dht11_h
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#if defined(ARDUINO) && (ARDUINO >= 100)
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#include <Arduino.h>
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#else
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#include <WProgram.h>
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#endif
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#define DHT11LIB_VERSION "0.4.1"
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#define DHTLIB_OK 0
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#define DHTLIB_ERROR_CHECKSUM -1
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#define DHTLIB_ERROR_TIMEOUT -2
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class dht11
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{
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public:
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    int read(int pin);
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int humidity;
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int temperature;
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};
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#endif
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</source>
  
 
<br><br>
 
<br><br>

2015年7月17日 (五) 17:15的版本

1 概述



2 库 

//
// FILE: dht11.cpp
// VERSION: 0.4.1
// PURPOSE: DHT11 Temperature & Humidity Sensor library for Arduino
// LICENSE: GPL v3 (http://www.gnu.org/licenses/gpl.html)
//
// DATASHEET: http://www.micro4you.com/files/sensor/DHT11.pdf
//
// HISTORY:
// George Hadjikyriacou - Original version (??)
// Mod by SimKard - Version 0.2 (24/11/2010)
// Mod by Rob Tillaart - Version 0.3 (28/03/2011)
// + added comments
// + removed all non DHT11 specific code
// + added references
// Mod by Rob Tillaart - Version 0.4 (17/03/2012)
// + added 1.0 support
// Mod by Rob Tillaart - Version 0.4.1 (19/05/2012)
// + added error codes
//

#include "dht11.h"

// Return values:
// DHTLIB_OK
// DHTLIB_ERROR_CHECKSUM
// DHTLIB_ERROR_TIMEOUT
int dht11::read(int pin)
{
	// BUFFER TO RECEIVE
	uint8_t bits[5];
	uint8_t cnt = 7;
	uint8_t idx = 0;

	// EMPTY BUFFER
	for (int i=0; i< 5; i++) bits[i] = 0;

	// REQUEST SAMPLE
	pinMode(pin, OUTPUT);
	digitalWrite(pin, LOW);
	delay(18);
	digitalWrite(pin, HIGH);
	delayMicroseconds(40);
	pinMode(pin, INPUT);

	// ACKNOWLEDGE or TIMEOUT
	unsigned int loopCnt = 10000;
	while(digitalRead(pin) == LOW)
		if (loopCnt-- == 0) return DHTLIB_ERROR_TIMEOUT;

	loopCnt = 10000;
	while(digitalRead(pin) == HIGH)
		if (loopCnt-- == 0) return DHTLIB_ERROR_TIMEOUT;

	// READ OUTPUT - 40 BITS => 5 BYTES or TIMEOUT
	for (int i=0; i<40; i++)
	{
		loopCnt = 10000;
		while(digitalRead(pin) == LOW)
			if (loopCnt-- == 0) return DHTLIB_ERROR_TIMEOUT;

		unsigned long t = micros();

		loopCnt = 10000;
		while(digitalRead(pin) == HIGH)
			if (loopCnt-- == 0) return DHTLIB_ERROR_TIMEOUT;

		if ((micros() - t) > 40) bits[idx] |= (1 << cnt);
		if (cnt == 0)   // next byte?
		{
			cnt = 7;    // restart at MSB
			idx++;      // next byte!
		}
		else cnt--;
	}

	// WRITE TO RIGHT VARS
        // as bits[1] and bits[3] are allways zero they are omitted in formulas.
	humidity    = bits[0]; 
	temperature = bits[2]; 

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

	if (bits[4] != sum) return DHTLIB_ERROR_CHECKSUM;
	return DHTLIB_OK;
}


// 
// FILE: dht11.h
// VERSION: 0.4.1
// PURPOSE: DHT11 Temperature & Humidity Sensor library for Arduino
// LICENSE: GPL v3 (http://www.gnu.org/licenses/gpl.html)
//
// DATASHEET: http://www.micro4you.com/files/sensor/DHT11.pdf
//
// URL: http://playground.arduino.cc/Main/DHT11Lib
//
// HISTORY:
// George Hadjikyriacou - Original version
// see dht.cpp file
// 

#ifndef dht11_h
#define dht11_h

#if defined(ARDUINO) && (ARDUINO >= 100)
#include <Arduino.h>
#else
#include <WProgram.h>
#endif

#define DHT11LIB_VERSION "0.4.1"

#define DHTLIB_OK				0
#define DHTLIB_ERROR_CHECKSUM	-1
#define DHTLIB_ERROR_TIMEOUT	-2

class dht11
{
public:
    int read(int pin);
	int humidity;
	int temperature;
};
#endif



3 参考

























来自“http://wiki.jackslab.org/index.php?title=DHT11_%E6%95%B0%E5%AD%97%E6%B8%A9%E6%B9%BF%E5%BA%A6%E4%BC%A0%E6%84%9F%E5%99%A8&oldid=4201”
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