//Sever
//=======================================================//
#include <DHT.h>                              // DHT22
#include <SPI.h>                              // SD
#include <Wire.h>                             // I2C->OLED
#include <Adafruit_GFX.h>                     // OLED
#include <Adafruit_SSD1306.h>                 // OLED
#include <Fonts/FreeMonoBoldOblique18pt7b.h>
#include <Fonts/TomThumb.h>
#include <ESP8266WiFi.h>
//=======================================================//
#define OLED_RESET LED_BUILTIN
Adafruit_SSD1306 oled(OLED_RESET);
#define DHTPIN 13                             // DHT pin (D7=13)3
#define DHTTYPE DHT11
//=======================================================//
WiFiServer server(80);                        // launches the server
IPAddress ip(192, 168, 1, 80);                // fix IP of the server
IPAddress gateway(192, 168, 1, 1);            // WiFi router's IP
IPAddress subnet(255, 255, 255, 0);
DHT dht(DHTPIN, DHTTYPE);
//=======================================================//
char ssid[] = "xxxxxxxxxxxxxx";
char pass[] = "xxxxxxxxxxxxxx";
unsigned long DHTtimer = 0;
float h, t;
unsigned long clientTimer = 0;
int led = D6;                                 // led pin
int tempset = 30;                             // the temperature to start the relay
//=======================================================//

void setup() {
  //  Serial.begin(115200);                   // only for debug
  dht.begin();
  Wire.begin();  // default SDA and SCL
  pinMode(led, OUTPUT);
  oled.begin(SSD1306_SWITCHCAPVCC, 0x3D);     // I2C address of my b&w OLED
  oled.setTextColor(WHITE);
  oled.setTextSize(1);
  oled.clearDisplay();
  oledre(0, 10, "Wemos DHT_server_02", 0);
  oled.display();
  server_start(0);                            // starts the WiFi server
  delay(2000);
}
//=======================================================//
void loop() {
  if (millis() > DHTtimer + 2000) {
    h = dht.readHumidity();
    t = dht.readTemperature();                // reads the DHT for temperature
        if (isnan(h) || isnan(t)) {
        return;
        } else {
    DHTtimer = millis();
    }
  }
                     
        if (t < tempset) {                    // if temp is lower than tempset
        digitalWrite(led, LOW);
    }
        if (t > tempset) {                    // if temp is higher than tempset
        digitalWrite(led, HIGH);              // turn on led
    }
  
   WiFiClient client = server.available();
        if (client) {
        oled.invertDisplay(true);
        String request = client.readStringUntil('\r');    // reads the message from the client
        client.flush();
        client.println(String(t, 1));                     // sends the temperature to the client
        client.print(":");                 
        oled.invertDisplay(true);
        client.stop();                                    // disconnects the client
        clientTimer = millis();
  }
        if (millis() - clientTimer > 30000) {             // stops and restarts the WiFi server after 30 sec
        WiFi.disconnect();                                // idle time
        delay(500);
        server_start(1);
  }
}
//=======================================================//
void server_start(byte restart) {
        if (restart) {
        oled.clearDisplay();
        oledre(0, 10, "Server restart", 0);
        oled.setCursor(0, 20);
        } else {
        oledre(0, 20, "Server start", 0);
        oled.setCursor(0, 30);
  }
      WiFi.config(ip, gateway, subnet);
      WiFi.begin(ssid, pass);
        while (WiFi.status() != WL_CONNECTED) {
        oled.print(".");
        oled.display();
        delay(500);
  }
        server.begin();
        delay(500);
        clientTimer = millis();
}
//=======================================================//
void ipOledre(byte xc) {
        oled.setFont(&TomThumb);
        oled.setCursor(xc + 35, 63);
        oled.setTextSize(1);
        oled.print(WiFi.localIP());
}
//=======================================================//
void oledre(byte x, byte y, String text, byte font) {
      Serial.println(text);
        if (font) {
        oled.setFont(&FreeMonoBoldOblique18pt7b);
        } else {
        oled.setFont(&TomThumb);
         }
        oled.setCursor(x, y);
        oled.print(text);
}
***************************************************************************
========================================================
***************************************************************************
//Client
//=========================================================//
#include <SPI.h>
#include <Wire.h>                                 // I2C->OLED
#include <Adafruit_GFX.h>                         // OLED
#include <Adafruit_SSD1306.h>                     // OLED
#include <Fonts/FreeMonoBoldOblique18pt7b.h>
#include <Fonts/TomThumb.h>
#include <ESP8266WiFi.h>
//=========================================================//
IPAddress server(192, 168, 1, 80);                // fix IP of the server
WiFiClient client;
#define OLED_RESET LED_BUILTIN
Adafruit_SSD1306 oled(OLED_RESET);
//=========================================================//
              char ssid[] = "xxxxxxxxxxxxxxxxx";
              char pass[] = "xxxxxxxxxxxxxxxxx";
              byte xc = 1, yc = 50, dx = 1, dy = 1;
              unsigned long askTimer = 0;
              unsigned long oledTimer = 0;
              String answer;
              uint8_t pinD1 = 5;                                // I2C Bus SCL (clock)
              uint8_t pinD2 = 4;                                // I2C Bus SDA (data)
              int led = D6;
            
//=========================================================//
              void setup() {
              Wire.begin(pinD2, pinD1);                       // SDA, SCL
              pinMode(led, OUTPUT);
              oled.begin(SSD1306_SWITCHCAPVCC, 0x3C);         // I2C address of my blue OLED
              oled.setTextColor(WHITE);
              oled.setTextSize(1);
              oled.clearDisplay();
              oledre(0, 10, "Wemos DHTkliens_011", 0);
              oled.display();
              WiFi.begin(ssid, pass);
              while (WiFi.status() != WL_CONNECTED) {
              delay(500);
              }
              }
//=========================================================//
              void loop () {
              if (millis() - askTimer > 2340) {                   // time between two connection to the server

              client.connect(server, 80);                         // connects to the server
              Serial.println(".");
              client.println("Haliho szerver!\r");                // trigger message to the server, its value is scrapped
              answer = client.readStringUntil('\r');              // received the server's answer
              String answer = client.readStringUntil('\r');       // receives the answer from the sever
              Serial.println("from server: " + answer);
              client.flush();
              askTimer = millis();
              }
              if (millis() - oledTimer > 50) {                       // timer to refresh the OLED
              oled.clearDisplay();
              oledre(xc, yc, answer + "C", 1);
              oled.display();
              oledTimer = millis();
              }
              }

//=========================================================//
              void oledre(byte x, byte y, String szoveg, byte font) {     // prints strings on the OLED
              if (font) {
              oled.setFont(&FreeMonoBoldOblique18pt7b);
              } else {
              oled.setFont(&TomThumb);
              }
              oled.setCursor(x, y);
              oled.print(szoveg);
              }
//=========================================================//