ESP8266 WiFi – Temperatuur en luchtvochtigheid sensor DHT 11 (ArduinoIDE)

Op deze pagina vind je een voorbeeld om via de ESP-01 module een DHT 11 module uit te lezen via een GPIO pin.

Hardware

Met deze module kun je de temperatuur en luchtvochtigheid meten, hij is door de fabrikant al behoorlijk geijkt, eventuele aanpassingen (bijvoorbeeld ijken) kunnen softwarematig gedaan worden.

Werkt op: 5V.
Temperatuur bereik: 0 – +50 ºC.
Temperatuur nauwkeurigheid: ±2,0 ºC.
Vochtigheid bereik: 20-95% RH.
Vochtigheid nauwkeurigheid: ±5,0% RH.
Response tijd: < 5 sec.

Pinout

Pin:	Functie:
01	+5V
02	Data
03	NC (niet aangesloten)
04	GND

De Keyes versie (met weerstand):

[table “6” not found /]

LET OP: Er zijn ook andere versie in omloop, controleer altijd de pinout of raadpleeg de handleiding!

Wat heb je nodig?

1) Firmware flashen met ArduinoIDE
2) PietteTech DHT8266 bibliotheek

Sluit de DHT module aan op GPIO 2 volgens onderstaand schema:

ESP8266 ESP-01 GPIO DHT11 schema

De code om de DHT module uit te lezen:

#include "PietteTech_DHT.h"

// system defines
#define DHTTYPE  DHT11           // Sensor type DHT11/21/22/AM2301/AM2302
#define DHTPIN   2              // Digital pin for communications

#define REPORT_INTERVAL 5000 // in msec must > 2000

// to check dht
unsigned long startMills;
float t, h, d;
int acquireresult;
int acquirestatus;

//declaration
void dht_wrapper(); // must be declared before the lib initialization

// Lib instantiate
PietteTech_DHT DHT(DHTPIN, DHTTYPE, dht_wrapper);

// globals
bool bDHTstarted;       // flag to indicate we started acquisition

// This wrapper is in charge of calling
// must be defined like this for the lib work
void dht_wrapper() {
  DHT.isrCallback();
}

void setup() {
  startMills = millis();
  Serial.begin(115200);

  /*
    while (!Serial) {
    yield(); // wait for serial port to connect.
    }
  */

  Serial.println("");
  Serial.println("DHT Example program using DHT.acquire and DHT.acquireAndWait");
  Serial.println("");

  // delay 2 sec before start acquire
  while ( (millis() - startMills) < 2000 ) {
    yield();
  }

  // blocking method
  acquirestatus = 0;
  acquireresult = DHT.acquireAndWait(1000);
  if ( acquireresult == 0 ) {
    t = DHT.getCelsius();
    h = DHT.getHumidity();
    d = DHT.getDewPoint();
  } else {
    t = h = d = 0;
  }
}

void loop() {
  if (bDHTstarted) {
    acquirestatus = DHT.acquiring();
    if (!acquirestatus) {
      acquireresult = DHT.getStatus();
      if ( acquireresult == 0 ) {
        t = DHT.getCelsius();
        h = DHT.getHumidity();
        d = DHT.getDewPoint();
      }
      bDHTstarted = false;
    }
  }

  if ((millis() - startMills) > REPORT_INTERVAL) {
    if ( acquireresult == 0 ) {
      Serial.println("");

      Serial.print("Humidity (%): ");
      Serial.println(h);

      Serial.print("Temperature (oC): ");
      Serial.println(t);

      Serial.print("Dew Point (oC): ");
      Serial.println(d);

    } else {
      Serial.println("Is dht22 connected");
    }
    startMills = millis();

    // to remove lock
    if (acquirestatus == 1) {
      DHT.reset();
    }

    if (!bDHTstarted) {
      // non blocking method
      DHT.acquire();
      bDHTstarted = true;
    }
  }
}

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#include "PietteTech_DHT.h"

// system defines

#define DHTTYPE DHT11 // Sensor type DHT11/21/22/AM2301/AM2302

#define DHTPIN 2 // Digital pin for communications

#define REPORT_INTERVAL 5000 // in msec must > 2000

// to check dht

unsigned long startMills;

float t, h, d;

int acquireresult;

int acquirestatus;

//declaration

void dht_wrapper(); // must be declared before the lib initialization

// Lib instantiate

PietteTech_DHT DHT(DHTPIN, DHTTYPE, dht_wrapper);

// globals

bool bDHTstarted; // flag to indicate we started acquisition

// This wrapper is in charge of calling

// must be defined like this for the lib work

void dht_wrapper() {

DHT.isrCallback();

}

void setup() {

startMills = millis();

Serial.begin(115200);

while (!Serial) {

yield(); // wait for serial port to connect.

}

Serial.println("");

Serial.println("DHT Example program using DHT.acquire and DHT.acquireAndWait");

Serial.println("");

// delay 2 sec before start acquire

while ( (millis() - startMills) < 2000 ) {

yield();

}

// blocking method

acquirestatus = 0;

acquireresult = DHT.acquireAndWait(1000);

if ( acquireresult == 0 ) {

t = DHT.getCelsius();

h = DHT.getHumidity();

d = DHT.getDewPoint();

} else {

t = h = d = 0;

}

void loop() {

if (bDHTstarted) {

acquirestatus = DHT.acquiring();

if (!acquirestatus) {

acquireresult = DHT.getStatus();

if ( acquireresult == 0 ) {

t = DHT.getCelsius();

h = DHT.getHumidity();

d = DHT.getDewPoint();

}

bDHTstarted = false;

}

if ((millis() - startMills) > REPORT_INTERVAL) {

if ( acquireresult == 0 ) {

Serial.println("");

Serial.print("Humidity (%): ");

Serial.println(h);

Serial.print("Temperature (oC): ");

Serial.println(t);

Serial.print("Dew Point (oC): ");

Serial.println(d);

} else {

Serial.println("Is dht22 connected");

}

startMills = millis();

// to remove lock

if (acquirestatus == 1) {

DHT.reset();

}

if (!bDHTstarted) {

// non blocking method

DHT.acquire();

bDHTstarted = true;

}

Console output:

Humidity (%): 36.00
Temperature (oC): 24.00
Dew Point (oC): 8.00

Humidity (%): 36.00

Temperature (oC): 24.00

Dew Point (oC): 8.00

De code om de DHT module uit te lezen via een website

LET OP: Gebaseerd op de Adafruit DHT.H bibliotheek!

1) Adafruit DHT11 bibliotheek

/* DHTServer - ESP8266 Webserver with a DHT sensor as an input

   Based on ESP8266Webserver, DHTexample, and BlinkWithoutDelay (thank you)

   Version 1.0  5/3/2014  Version 1.0   Mike Barela for Adafruit Industries
*/
#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266WebServer.h>
#include <DHT.h>
#define DHTTYPE DHT11
#define DHTPIN  2

const char* ssid     = "SSID";
const char* password = "WACHTWOORD";

ESP8266WebServer server(80);
 
// Initialize DHT sensor 
// NOTE: For working with a faster than ATmega328p 16 MHz Arduino chip, like an ESP8266,
// you need to increase the threshold for cycle counts considered a 1 or 0.
// You can do this by passing a 3rd parameter for this threshold.  It's a bit
// of fiddling to find the right value, but in general the faster the CPU the
// higher the value.  The default for a 16mhz AVR is a value of 6.  For an
// Arduino Due that runs at 84mhz a value of 30 works.
// This is for the ESP8266 processor on ESP-01 
DHT dht(DHTPIN, DHTTYPE, 11); // 11 works fine for ESP8266
 
float humidity, temp_f;  // Values read from sensor
String webString="";     // String to display
// Generally, you should use "unsigned long" for variables that hold time
unsigned long previousMillis = 0;        // will store last temp was read
const long interval = 2000;              // interval at which to read sensor
 
void handle_root() {
  server.send(200, "text/plain", "Hello from the weather esp8266, read from /temp or /humidity");
  delay(100);
}

void gettemperature() {
  // Wait at least 2 seconds seconds between measurements.
  // if the difference between the current time and last time you read
  // the sensor is bigger than the interval you set, read the sensor
  // Works better than delay for things happening elsewhere also
  unsigned long currentMillis = millis();
 
  if(currentMillis - previousMillis >= interval) {
    // save the last time you read the sensor 
    previousMillis = currentMillis;   

    // Reading temperature for humidity takes about 250 milliseconds!
    // Sensor readings may also be up to 2 seconds 'old' (it's a very slow sensor)
    humidity = dht.readHumidity();          // Read humidity (percent)
    temp_f = dht.readTemperature(true);     // Read temperature as Fahrenheit
    // Check if any reads failed and exit early (to try again).
    if (isnan(humidity) || isnan(temp_f)) {
      Serial.println("Failed to read from DHT sensor!");
      return;
    }
  }
}

void setup(void) {
  // You can open the Arduino IDE Serial Monitor window to see what the code is doing
  Serial.begin(115200);  // Serial connection from ESP-01 via 3.3v console cable
  dht.begin();           // initialize temperature sensor

  // Connect to WiFi network
  WiFi.begin(ssid, password);
  Serial.print("\n\r \n\rWorking to connect");

  // Wait for connection
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("DHT Weather Reading Server");
  Serial.print("Connected to ");
  Serial.println(ssid);
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());
   
  server.on("/", handle_root);
  
  server.on("/temp", [](){  // if you add this subdirectory to your webserver call, you get text below :)
    gettemperature();       // read sensor
    webString="Temperature: "+String((int)temp_f)+" F";   // Arduino has a hard time with float to string
    server.send(200, "text/plain", webString);            // send to someones browser when asked
  });

  server.on("/humidity", [](){  // if you add this subdirectory to your webserver call, you get text below :)
    gettemperature();           // read sensor
    webString="Humidity: "+String((int)humidity)+"%";
    server.send(200, "text/plain", webString);               // send to someones browser when asked
  });
  
  server.begin();
  Serial.println("HTTP server started");
}
 
void loop(void) {
  server.handleClient();
}

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/* DHTServer - ESP8266 Webserver with a DHT sensor as an input

Based on ESP8266Webserver, DHTexample, and BlinkWithoutDelay (thank you)

Version 1.0 5/3/2014 Version 1.0 Mike Barela for Adafruit Industries

#include <ESP8266WiFi.h>

#include <WiFiClient.h>

#include <ESP8266WebServer.h>

#include <DHT.h>

#define DHTTYPE DHT11

#define DHTPIN 2

const char* ssid = "SSID";

const char* password = "WACHTWOORD";

ESP8266WebServer server(80);

// Initialize DHT sensor

// NOTE: For working with a faster than ATmega328p 16 MHz Arduino chip, like an ESP8266,

// you need to increase the threshold for cycle counts considered a 1 or 0.

// You can do this by passing a 3rd parameter for this threshold. It's a bit

// of fiddling to find the right value, but in general the faster the CPU the

// higher the value. The default for a 16mhz AVR is a value of 6. For an

// Arduino Due that runs at 84mhz a value of 30 works.

// This is for the ESP8266 processor on ESP-01

DHT dht(DHTPIN, DHTTYPE, 11); // 11 works fine for ESP8266

float humidity, temp_f; // Values read from sensor

String webString=""; // String to display

// Generally, you should use "unsigned long" for variables that hold time

unsigned long previousMillis = 0; // will store last temp was read

const long interval = 2000; // interval at which to read sensor

void handle_root() {

server.send(200, "text/plain", "Hello from the weather esp8266, read from /temp or /humidity");

delay(100);

}

void gettemperature() {

// Wait at least 2 seconds seconds between measurements.

// if the difference between the current time and last time you read

// the sensor is bigger than the interval you set, read the sensor

// Works better than delay for things happening elsewhere also

unsigned long currentMillis = millis();

if(currentMillis - previousMillis >= interval) {

// save the last time you read the sensor

previousMillis = currentMillis;

// Reading temperature for humidity takes about 250 milliseconds!

// Sensor readings may also be up to 2 seconds 'old' (it's a very slow sensor)

humidity = dht.readHumidity(); // Read humidity (percent)

temp_f = dht.readTemperature(true); // Read temperature as Fahrenheit

// Check if any reads failed and exit early (to try again).

if (isnan(humidity) || isnan(temp_f)) {

Serial.println("Failed to read from DHT sensor!");

return;

}

void setup(void) {

// You can open the Arduino IDE Serial Monitor window to see what the code is doing

Serial.begin(115200); // Serial connection from ESP-01 via 3.3v console cable

dht.begin(); // initialize temperature sensor

// Connect to WiFi network

WiFi.begin(ssid, password);

Serial.print("\n\r \n\rWorking to connect");

// Wait for connection

while (WiFi.status() != WL_CONNECTED) {

delay(500);

Serial.print(".");

}

Serial.println("");

Serial.println("DHT Weather Reading Server");

Serial.print("Connected to ");

Serial.println(ssid);

Serial.print("IP address: ");

Serial.println(WiFi.localIP());

server.on("/", handle_root);

server.on("/temp", [](){ // if you add this subdirectory to your webserver call, you get text below :)

gettemperature(); // read sensor

webString="Temperature: "+String((int)temp_f)+" F"; // Arduino has a hard time with float to string

server.send(200, "text/plain", webString); // send to someones browser when asked

});

server.on("/humidity", [](){ // if you add this subdirectory to your webserver call, you get text below :)

gettemperature(); // read sensor

webString="Humidity: "+String((int)humidity)+"%";

server.send(200, "text/plain", webString); // send to someones browser when asked

});

server.begin();

Serial.println("HTTP server started");

}

void loop(void) {

server.handleClient();

}

Console output:

Working to connect.......
DHT Weather Reading Server
Connected to SSID
IP address: 192.168.0.117
HTTP server started

Working to connect.......

DHT Weather Reading Server

Connected to SSID

IP address: 192.168.0.117

HTTP server started

Server HTTP output:

192.168.0.117

Hello from the weather esp8266, read from /temp or /humidity

192.168.0.117/temp

Temperature: 70 F

192.168.0.117/humidity

Humidity: 57%

Bron:
learn.adafruit.com

Zoeken

ESP8266 WiFi – Temperatuur en luchtvochtigheid sensor DHT 11 (ArduinoIDE)

Hardware

Pinout

De code om de DHT module uit te lezen via een website