[vc_row][vc_column width=”1/1″][vc_column_text]DHT11 Temperature and Humidity Sensor features a calibrated digital signal output with the temperature and humidity sensor complex,ensureing the high reliability and excellent long-term stability. A high-performance 8-bit microcontroller is connected. This sensor includes a resistive element and a sense of wet NTC temperature measuring devices. It has excellent quality, fast response, anti-interference ability and high cost performance advantages.

DHT11 pin explanation:

[table]

Pin, Name,  Comments

1,VDD, Suppy 3-5.5V

2, DATA, Single wire serial data

3, NC, floating

4, GND, Ground

[/table]

[/vc_column_text][vc_tour][vc_tab title=”BOM” tab_id=”1384469281-1-13″][vc_column_text]1. pcDuino experiment platform

2. 1 x RED LED

3. 1 x Yellow LED

4. 2 x resistors of 220 ohm

5. 1 x resistor of 10K ohm

6. Jump wire[/vc_column_text][/vc_tab][vc_tab title=”Wire Diagram” tab_id=”1384469281-2-47″][vc_column_text][/vc_column_text][/vc_tab][vc_tab title=”Sample Code” tab_id=”1384469693949-2-10″][vc_column_text]The full code can be downloaded from here ( DHT11).

Copy the directory named ‘dht’ to directory /home/ubuntu/Arduino/libraries on pcDuino.

Restart the application Arduino IDE:

The main code is as following:

#include <core.h>

#include <dht11.h>

dht11 DHT11;

#define DHT11PIN 7

int H_Led = 2;
int T_Led = 3;

void setup()
{
pinMode(H_Led,OUTPUT);
pinMode(T_Led,OUTPUT);
printf("DHT11 Monitoring\n");
}

void loop()
{
int val = DHT11.read(DHT11PIN);

printf("Read sensor: %d\n", val);

switch (val)
{
case DHTLIB_OK:
printf("OK \n");
break;
case DHTLIB_ERROR_CHECKSUM:
printf("Checksum error\n");
break;
case DHTLIB_ERROR_TIMEOUT:
printf("Time out error\n");
break;
default:
printf("Unknown error\n");
break;
}

printf("Humidity (%): %f", (float)DHT11.humidity);

if((DHT11.humidity<=40)||(DHT11.humidity>=60))
digitalWrite(H_Led,HIGH);
else
digitalWrite(H_Led,LOW);

printf("Temperature (oC): %f", (float)DHT11.temperature);

if((DHT11.temperature<=18)||(DHT11.temperature>=25))
digitalWrite(T_Led,HIGH);
else
digitalWrite(T_Led,LOW);
delay(2000);
}

[/vc_column_text][/vc_tab][vc_tab title=”Results” tab_id=”1384469855497-3-0″][vc_column_text]The LED will turn yellow when the temperature feel good, and turn red when it is not suitable.

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