nodeMCU DHT11 display and wifi server

nodeMCU_dht11_display_wifi.cpp

#include <LiquidCrystal_I2C.h>
#include <Wire.h>
#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266WebServer.h>
#include <ESP8266mDNS.h>
#include <limits>

#include <DHT.h>
#include <DHT_U.h>

#ifndef STASSID
#define STASSID "foo"
#define STAPSK  "bar"
#endif

const char* ssid = STASSID;
const char* password = STAPSK;

ESP8266WebServer server(80);

int D0 = 16;
int D1 = 5;
int D2 = 4;
int D3 = 0;
int D4 = 2;
int D5 = 14;
int D6 = 12;
int D7 = 13;
int D8 = 15;
int RX = 3;

LiquidCrystal_I2C lcd(0x27, 16, 2);

#define DHTPIN            D0         // Pin which is connected to the DHT sensor.
#define DHTTYPE           DHT11     // DHT 11
//#define DHTTYPE           DHT22     // DHT 22 (AM2302)
//#define DHTTYPE           DHT21     // DHT 21 (AM2301)

DHT_Unified dht(DHTPIN, DHTTYPE);

static float lastTemperature = std::numeric_limits<float>::infinity();

void setup() {
  Serial.begin(115200);
  Wire.begin(D2, D1);
  dht.begin();

  lcd.begin(16, 2);
  lcd.home();
  // Print a message to the LCD.
  lcd.print("Measuring temp!");
  lcd.setCursor(0, 1);
  lcd.backlight();

  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);

  lcd.setCursor(0, 1);
  lcd.print("connecting");

  // Wait for connection
  while (WiFi.status() != WL_CONNECTED) {
    lcd.print(".");
    delay(400);
  }

  lcd.setCursor(0, 0);
  String status1 = String("IP:" + WiFi.localIP().toString() + "     ");
  lcd.print(status1);

  if (MDNS.begin("esp8266")) {
    lcd.setCursor(0, 1);
    lcd.print("connected          ");
  } else {
    lcd.setCursor(0, 1);
    lcd.print("MDNS failed          ");
    delay(2000);
  }

  server.on("/", handleRoot);
  server.begin();
}


void handleRoot() {
  String tempString = String(lastTemperature, 3);
  String d = String("It's " + tempString + " C here!");

  if (lastTemperature == std::numeric_limits<float>::infinity()) {
    d = String("no measurements done yet");
  }

  //  digitalWrite(led, 1);
  server.send(200, "text/plain", d);
  //  digitalWrite(led, 0);
}


// the loop function runs over and over again forever
void loop() {
  //  digitalWrite(D4, HIGH);
  delay(50);
  //  digitalWrite(D4, LOW);
  delay(50);
  lcd.setCursor(0, 1);

  sensors_event_t event;
  dht.temperature().getEvent(&event);

  if (isnan(event.temperature) == false) {
    lastTemperature = event.temperature;

    String tempString = String(event.temperature, 3);
    String d = String(tempString + " 'C    ");

    lcd.print(d);
  } else {
    lcd.print("temp fail! ");
  }
  server.handleClient();
  MDNS.update();
}