esp8266-wifi-dht11-ground-humidity-thingspeak.ino

#include <DHT.h>  // Including library for dht

#include <ESP8266WiFi.h>

String THINGSPEAK_API_KEY = "THINGSPEAK_API_KEY";

const char *ssid =  "WIFI-SSID";
const char *pass =  "WIFI-PASS";
const char *server = "api.thingspeak.com";

#define DHTPIN D3          //pin where the dht11 is connected

DHT dht(DHTPIN, DHT11);

WiFiClient client;

void setup() {
  Serial.begin(115200);
  delay(10);
  dht.begin();

  WiFi.begin(ssid, pass);

  Serial.print("Conectando em ");
  Serial.print(ssid);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("");
  Serial.print("Conectado em ");
  Serial.println(ssid);

}

void loop() {

  int groundHumidity = analogRead(A0);   // read the input on analog pin 0

  float h = dht.readHumidity();
  float t = dht.readTemperature();

  if (isnan(h) || isnan(t)) {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }

  if (client.connect(server,80)) {  
  
    String postStr = THINGSPEAK_API_KEY;
    
    postStr +="&field1=";
    postStr += String(t);
    postStr +="&field2=";
    postStr += String(h);
    postStr +="&field3=";
    postStr += groundHumidity;
    postStr += "\r\n\r\n";
    
    client.print("POST /update HTTP/1.1\n");
    client.print("Host: api.thingspeak.com\n");
    client.print("Connection: close\n");
    client.print("X-THINGSPEAKAPIKEY: " + THINGSPEAK_API_KEY + "\n");
    client.print("Content-Type: application/x-www-form-urlencoded\n");
    client.print("Content-Length: ");
    client.print(postStr.length());
    client.print("\n\n");
    client.print(postStr);
    
    Serial.print("Umidade do solo: ");

    if (groundHumidity >= 0 && groundHumidity < 400) {
      Serial.print("Umido (");
    }
 
    if (groundHumidity > 400 && groundHumidity < 800) {
      Serial.print("Moderado ("); 
    }
   
    if (groundHumidity > 800 && groundHumidity <= 1024) {
      Serial.print("Seco (");
    }

    Serial.print(groundHumidity);
    Serial.println(")");
    
    Serial.print("Temperatura: ");
    Serial.print(t);
    Serial.println("º C");
    Serial.print("Umidade do ar: ");
    Serial.print(h);
    Serial.println("%");
    Serial.println("Dados enviados.");
  
  }
  
  client.stop();
  
  Serial.print("Aguardando próxima leitura");

  for (int idx = 0; idx < 15; idx++) {
    Serial.print(".");
    delay(1000);
  }

  Serial.println("");
}