NodeMCU_DHT22_Thingspeak_Arduino_IDE

#include <ESP8266WiFi.h>
#include "DHT.h"


#define AP_SSID     "xxxxx"
#define AP_PASSWORD "xxxxxx"


#define API_KEY "xxxxx"
#define REPORT_INTERVAL 60 // in sec


#define THINGSPEAK_CLOUD_ADDRESS     "api.thingspeak.com"
#define THINGSPEAK_CLOUD_PORT        80



#define DHT22_PIN 13  // DHT22 pin


float oldTemp;
float oldHum;

DHT dht;


void setup() {
  Serial.begin(115200);

  wifiConnect();

  Serial.println();
  Serial.println("Status\tHumidity (%)\tTemperature (C)\t(F)");

  dht.setup(DHT22_PIN); // data pin 2

  oldTemp = -1;
  oldHum = -1;
}

void loop() {
  delay(dht.getMinimumSamplingPeriod());

  float hum = dht.getHumidity();
  float temp = dht.getTemperature();

  Serial.print(dht.getStatusString());
  Serial.print("\t");
  Serial.print(hum, 1);
  Serial.print("\t\t");
  Serial.print(temp, 1);
  Serial.print("\t\t");
  Serial.println(dht.toFahrenheit(temp), 1);

  if (temp != oldTemp)
  {
    sendTeperature(temp);
    oldTemp = temp;
  }

  if (hum != oldHum)
  {
    sendHumidity(hum);
    oldHum = hum;
  }

  int cnt = REPORT_INTERVAL;

  while(cnt--)
    delay(1000);
}

void wifiConnect()
{
    Serial.print("Connecting to AP");
    WiFi.begin(AP_SSID, AP_PASSWORD);
    while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.print(".");
  }

  Serial.println("");
  Serial.println("WiFi connected");
}

void sendTeperature(float temp)
{
   WiFiClient client;

   while(!client.connect(THINGSPEAK_CLOUD_ADDRESS, THINGSPEAK_CLOUD_PORT)) {
    Serial.println("connection failed");
    wifiConnect();
  }

  String url = "";

  url += "/update?api_key="+ String(API_KEY) + "&field2="+String(temp);

  Serial.print("POST data to URL: ");
  Serial.println(url);

  client.print(String("POST ") + url + " HTTP/1.1\r\n" +
               "Host: " + String(THINGSPEAK_CLOUD_ADDRESS) + "\r\n" +
               "Connection: close\r\n" +
               "Content-Length: 0\r\n" +
               "\r\n");

  delay(100);
    while(client.available()){
    String line = client.readStringUntil('\r');
    Serial.print(line);
  }

  Serial.println();
  Serial.println("Connection closed");
}

void sendHumidity(float hum)
{
   WiFiClient client;

   while(!client.connect(THINGSPEAK_CLOUD_ADDRESS, THINGSPEAK_CLOUD_PORT)) {
    Serial.println("connection failed");
    wifiConnect();
  }

  String url = "";

  url += "/update?api_key="+ String(API_KEY) + "&field1="+String(hum);

  Serial.print("POST data to URL: ");
  Serial.println(url);

  client.print(String("POST ") + url + " HTTP/1.1\r\n" +
               "Host: " + String(THINGSPEAK_CLOUD_ADDRESS) + "\r\n" +
               "Connection: close\r\n" +
               "Content-Length: 0\r\n" +
               "\r\n");

  delay(100);
    while(client.available()){
    String line = client.readStringUntil('\r');
    Serial.print(line);
  }

  Serial.println();
  Serial.println("Connection closed");
}