/***************** DHT ******************/
#define DHTPIN 8
#include "DHTStable.h" // DHT library test sketch for DHT22/DHT11 && Arduino "AUTHOR: Rob Tillaart"
                       // URL: https://github.com/RobTillaart/DHTstable
DHTStable DHT;         // Initialize the DHT Library
int HUM  = 0;
int TEMP = 0;
/***************************************/
/**************** OLED *****************/
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#define SCREEN_WIDTH 128 // OLED display width,  in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels
// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);
/***************************************/

void setup() 
{
  Serial.begin(115200);
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // Address 0x3D for 128x64
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);
  };
}

void loop() 
{
  /****** For DHT22 *******/
  //int chk = DHT.read22(DHTPIN);
  /************************/
  /****** For DHT11 *******/
  int chk = DHT.read11(DHTPIN);
  /************************/
  HUM  = DHT.getHumidity();    // Read the humidity
  TEMP = DHT.getTemperature(); // Read the temperature

  /**** Display Data *****/
  Serial.print("Humidity");Serial.println(HUM);
  Serial.print("Temperature");Serial.println(TEMP);
  display.clearDisplay();
  oledDisplayHeader();
  oledDisplay(3,5,28,HUM,"%");  // Display humidity
  oledDisplay(2,70,16,TEMP,"C");// Display temperature 
  display.display();
  /************************/
  delay(2000); 
}

/*************** Generate OLED Header ***************/
void oledDisplayHeader()
{
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setCursor(0, 0);
  display.print("Humidity");
  display.setCursor(60, 0);
  display.print("Temperature");
}

/*************** Generate OLED Display ***************/
void oledDisplay(int size, int x,int y, float value, String unit)
{
  int charLen = 12;
  int xo      = x + charLen*3.2;
  int xunit   = x + charLen*3.6;
  int xval    = x; 
  display.setTextSize(size);
  display.setTextColor(WHITE);
 
  if (unit=="%"){
    display.setCursor(x, y);
    display.print(value,0);
    display.print(unit);
  } else {
    if (value>99){ xval  = x; } 
    else         { xval = x + charLen; };
    display.setCursor(xval, y);
    display.print(value,0);
    display.drawCircle(xo, y + 2, 2, WHITE);  // Print degree symbols
    display.setCursor(xunit, y);
    display.print(unit);
  };
}