[5th Week] DHT11 Temperature & Humidity Sensor

One of sensors I selected for my testing is temperature sensor. DHT11 includes temperature sensor, and humidity sensor.

Here's DHT11 board. Originally, it is just blue unit on the top with 4 pins, and it should be connected with resistor. However, this consists resistor in its board, and has only 3 pins except useless pin.

I connected it to Arduino board, and pin connection is like this.

(Arduino <-> DHT11)

5V <-> + (VCC)

GND <-> - (GND)

DIGITAL 2 <-> DATA

From now on, I can check data from sensor on Arduino with this code below. We can use DHT11 library for Arduino. It could be easily found in the website.

#include <DHT11.h>

int pin=2;

DHT11 dht11(pin); 

void setup()

{

   Serial.begin(9600);

  while (!Serial) {

      ; // wait for serial port to connect. Needed for Leonardo only

    }

}

void loop()

{

  int err;

  float temp, humi;

  if((err=dht11.read(humi, temp))==0)

  {

    Serial.println("*DHT11*");

    Serial.print("temperature: ");

    Serial.println(temp);

    Serial.print("humidity: ");

    Serial.println(humi);

  }

  else

  {

    Serial.println();

    Serial.print("Error No :");

    Serial.print(err);

    Serial.println();    

  }

  delay(1000); //delay for reread

}

With this, data is sent to RPi through serial connection. For capturing data on RPi, this python code can work.

import sys
import serial

port = "/dev/ttyACM0"
serialFromArduino = serial.Serial(port, 9600)
serialFromArduino.flushInput()

def getSensorData():
    print('*DHT11*')
    input1 = serialFromArduino.readline()
    print(input1)
    tem = input1.split()[1]
    input2 = serialFromArduino.readline()
    print(input2)
    hum = input2.split()[1]
    return (float(tem), float(hum))

def main():
    print('starting...')

    while True:
        if(serialFromArduino.inWaiting() > 0):
            if(serialFromArduino.readline().find('*') != -1):
                tem, hum = getSensorData()
            
if __name__ == '__main__':
    main()

Result looks like this.