DHT11 Dew-Point Calculator

/*     
 RedTar4
 Bobs_DewPoint_LCD_meter_DHT22_rev7
 10/18/18 - 3/10/19
 */  

     //  Library section
#include <LiquidCrystal.h>                // LCD library
  LiquidCrystal lcd(7, 8, 9, 10, 11, 12); // (rs,e,d4,d5,d6,d7),initialize the LCD with the numbers of the interface pins
#include <DHT.h>                          // DHT22 library, delete any "DHT.U" files from library,or it wont run
 
     //  Definition section
#define DHTPIN 2            // what arduino pin we're connected to, arduino pin D2
  DHT dht(DHTPIN, DHT22);   // initialize DHT sensor and create sensor objects
#define DHTTYPE DHT22       // create DHT 22  (AM2302), AM2321 object
   
     //  pin assignment section
int alarmLed = 3; //  assigns alarmLed int to arduino pin D3
 
void setup()
  {
     //  initilize and start systems
  Serial.begin(9600); //  sets up serial comm's to 9600 baud
  dht.begin();        //  initialize the DHT22
  lcd.begin(16, 2);   //  initialize the LCD's number of columns and rows
 
     //  display and serial print initilization
  Serial.println("DHTxx test!");
  lcd.setCursor(0, 1); lcd.print("DHTxx test!");
  delay(1500);
  
     //  output pin setup section
  pinMode(alarmLed, OUTPUT);   //  assigns alarmLed (arduino pin 3) as an output
  digitalWrite(alarmLed, LOW); //  sets output alarmLed (arduino pin 3) low

  }
 
void loop()
  {
     // Reading temperature and humidity takes about 250 milliseconds
  float H = dht.readHumidity();        //  read humitity as %f
  float C = dht.readTemperature();     //  read temperature as Celsius (default)
  float F = dht.readTemperature(true); //  read temperature as Fahrenheit (if true)
 
     // DHT22 data error check section
  if (isnan(H) || isnan(C) || isnan(F))
     {
    Serial.println("Failed to read from DHT sensor!");
    lcd.setCursor(0, 0); lcd.print("                ");
    lcd.setCursor(0, 0); lcd.print(" Failed to read ");
    lcd.setCursor(0, 1); lcd.print("                ");
    lcd.setCursor(0, 1); lcd.print("DHT sensor Fail!");
    return;   //  returns to start of loop
     }

    //  calculations and conversions section
  float HiF = dht.computeHeatIndex(F, H); //  read and compute heat index in Fahrenheit (the default)
  float DewPoint = (C - (100 - H) / 5);   //  dewpoint calculation using Celsius value
  float DP = (DewPoint * 9 / 5) + 32;     //  converts dewPoint calculation to fahrenheit

     //  alarm output section
  if ((F - 2) <= DP)                 //  if the F value - 2 is <= to the DP value then this statement is true
     {digitalWrite(alarmLed, HIGH);} //  since statement is true set alarmLed (arduino pin D3) high
   else                              //  if statement is not true then
     {digitalWrite(alarmLed, LOW);}  //  set alarmLed (arduino pin D3) low

     //  serial monitor and debug section
  Serial.print("Sample OK: ");                                //  prints sample ok to serial monitor
  Serial.print((int)C);        Serial.print(" *C, ");         //  prints celsius value to serial monitor and returns cursor
  Serial.print((int)F);        Serial.print(" *F, ");         //  prints fahrenheit value to serial monitor and returns cursor
  Serial.print((int)H);        Serial.print(" %, ");          //  prints humidity value to serial monitor and returns cursor
  Serial.print((int)DP);       Serial.print(" DP, ");         //  prints dewpoint value to serial monitor and returns cursor to next line
  Serial.print((int)HiF);      Serial.print(" Heat index, "); //  prints humidity value to serial monitor and returns cursor
  Serial.print((int)DewPoint); Serial.println(" DewP, ");     //  prints dewpoint value to serial monitor and returns cursor to next line

     //  LCD print section
  lcd.setCursor(0,  0); lcd.print("Tmp");
  lcd.setCursor(4,  0); lcd.print(F);
  lcd.setCursor(6,  0); lcd.print((char)223); lcd.print("F"); //  prints the degree's symbol
  lcd.setCursor(8,  0); lcd.print("Dew");
  lcd.setCursor(12, 0); lcd.print(DP);
  lcd.setCursor(14, 0); lcd.print((char)223); lcd.print("F"); //  prints the degree's symbol
  lcd.setCursor(0,  1); lcd.print("Hum ");
  lcd.setCursor(4,  1); lcd.print(H);
  lcd.setCursor(6,  1); lcd.print(" % ");
  lcd.setCursor(8,  1); lcd.print("HId");
  lcd.setCursor(12, 1); lcd.print(HiF);
  lcd.setCursor(14, 1); lcd.print((char)223); lcd.print("F"); //  prints the degree's symbol
 
     // The DHT22 sampling rate is .5HZ (.5 Sec), this delay sets program sample rate to match so no errors happen
  delay(2000);

  }