RaspberryPi - KY-015_DHT11(온도, 습도 센서)

출처 : java - read temperature from DHT11, using pi4j - Stack Overflow

pi4j 다운로드

$ mkdir pi4j
$ cd pi4j
$ wget http://get.pi4j.com/download/pi4j-1.0.zip
--2016-07-09 16:59:31--  http://get.pi4j.com/download/pi4j-1.0.zip
Resolving get.pi4j.com (get.pi4j.com)... 54.231.114.185
Connecting to get.pi4j.com (get.pi4j.com)|54.231.114.185|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 3807428 (3.6M) [application/zip]
Saving to: ‘pi4j-1.0.zip.1’
 
pi4j-1.0.zip.1      100%[=====================>]   3.63M   544KB/s   in 6.4s   
 
2016-07-09 16:59:38 (581 KB/s) - ‘pi4j-1.0.zip.1’ saved [3807428/3807428]
 
$ unzip pi4j-1.0.zip 

핀 연결

   

DHT11.java

import java.util.List;
import java.util.ArrayList;

import com.pi4j.wiringpi.Gpio;
import com.pi4j.wiringpi.GpioUtil;

public class DHT11 {
	private static final int MAXTIMINGS = 85;
	private int[] dht11_dat = { 0, 0, 0, 0, 0 };

	public DHT11() {

	    // setup wiringPi
	    if (Gpio.wiringPiSetup() == -1) {
	        System.out.println(" ==>> GPIO SETUP FAILED");
	        return;
	    }

	   GpioUtil.export(3, GpioUtil.DIRECTION_OUT);            
	}

	public void getTemperature() {
	   int laststate = Gpio.HIGH;
	   int j = 0;
	   dht11_dat[0] = dht11_dat[1] = dht11_dat[2] = dht11_dat[3] = dht11_dat[4] = 0;
	   StringBuilder value = new StringBuilder();

	   Gpio.pinMode(3, Gpio.OUTPUT);
	   Gpio.digitalWrite(3, Gpio.LOW);
	   Gpio.delay(18);

	   Gpio.digitalWrite(3, Gpio.HIGH);        
	   Gpio.pinMode(3, Gpio.INPUT);

	   for (int i = 0; i < MAXTIMINGS; i++) {
	      int counter = 0;
	      while (Gpio.digitalRead(3) == laststate) {
	          counter++;
	          Gpio.delayMicroseconds(1);
	          if (counter == 255) {
	              break;
	          }
	      }

	      laststate = Gpio.digitalRead(3);

	      if (counter == 255) {
	          break;
	      }

	      /* ignore first 3 transitions */
	      if ((i >= 4) && (i % 2 == 0)) {
	         /* shove each bit into the storage bytes */
	         dht11_dat[j / 8] <<= 1;
	         if (counter > 16) {
	             dht11_dat[j / 8] |= 1;
	         }
	         j++;
	       }
	    }
	    // check we read 40 bits (8bit x 5 ) + verify checksum in the last
	    // byte
	    if ((j >= 40) && checkParity()) {
	        float h = (float)((dht11_dat[0] << 8) + dht11_dat[1]) / 10;
	        if ( h > 100 )
	        {
	            h = dht11_dat[0];   // for DHT11
	        }
	        float c = (float)(((dht11_dat[2] & 0x7F) << 8) + dht11_dat[3]) / 10;
	        if ( c > 125 )
	        {
	            c = dht11_dat[2];   // for DHT11
	        }
	        if ( (dht11_dat[2] & 0x80) != 0 )
	        {
	            c = -c;
	        }
	        float f = c * 1.8f + 32;
	        System.out.println( "Humidity = " + h + " Temperature = " + c + "(" + f + "f)");
	    }else  {
	        System.out.println( "Data not good, skip" );
	    }

	}

	private boolean checkParity() {
	  return (dht11_dat[4] == ((dht11_dat[0] + dht11_dat[1] + dht11_dat[2] + dht11_dat[3]) & 0xFF));
	}



	public static void main (String ars[]) throws Exception {

	    DHT11 dht = new DHT11();

	    for (int i=0; i<10; i++) {
	       Thread.sleep(2000);
	       dht.getTemperature();
	    }

	    System.out.println("Done!!");

	}
}

컴파일

$ javac -cp pi4j-1.0/lib/pi4j-core.jar DHT11.java 

실행

$ sudo java -cp .:pi4j-1.0/lib/pi4j-core.jar DHT11 
Humidity = 56.0 Temperature = 32.0(89.6f)
Data not good, skip
Humidity = 53.0 Temperature = 31.0(87.8f)
Data not good, skip
Humidity = 52.0 Temperature = 31.0(87.8f)
Humidity = 52.0 Temperature = 31.0(87.8f)
Data not good, skip
Humidity = 51.0 Temperature = 31.0(87.8f)
Humidity = 51.0 Temperature = 31.0(87.8f)
Data not good, skip
Done!!

GPIO 핀 배열