#include <SPI.h>
#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 SSD1306 display connected using software SPI (default case):
#define OLED_MOSI  MOSI   //Connect SSD1315 D1
#define OLED_CLK  SCK     //Connect SSD1315 D0
#define OLED_DC  D4      //Connect SSD1315 D/C
#define OLED_CS  SS      //Connect SSD1315 CS
#define OLED_RESET  D5   //Connect SSD1315 RES
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT,
  OLED_MOSI, OLED_CLK, OLED_DC, OLED_RESET, OLED_CS);

void setup() {
  Serial.begin(9600);
  if(!display.begin(SSD1306_SWITCHCAPVCC)) {
    Serial.println(F("SSD1306 allocation failed"));
    for(;;); // Don't proceed, loop forever
  }
}

void loop() {
  display.clearDisplay();
  display.setTextSize(1);             // Normal 1:1 pixel scale
  display.setTextColor(SSD1306_WHITE);        // Draw white text
  display.setCursor(0,3);             // Start at top-left corner
  display.println(F("Hello"));
  display.setTextSize(2); 
  display.setCursor(0,16);  
  display.println(F("Hello"));
  display.setTextSize(3); 
  display.setCursor(0,38);  
  display.println(F("Hello"));
  display.display();
  delay(2000);
}