//=================================================================
// Project : Use I2C OLED 128x64  
//
// Date    : 2019-03-12
// Version : 1.0
//
// Note:
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY : without even the implied warranty of 
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE
//
// Hardware
// 1. Arduino UNO
// 2. I2C OLED 128x64 
// Libraries needed:
// https://github.com/adafruit/Adafruit_SSD1306
// https://github.com/adafruit/Adafruit-GFX-Library
//=================================================================
#include <Adafruit_GFX.h>      // Include core graphics library for the display
#include <Adafruit_SSD1306.h>  // Include Adafruit_SSD1306 library to drive the display
#include <Fonts/FreeMonoBold12pt7b.h>  // Add a custom font
#include <Fonts/FreeMono9pt7b.h>      // Add a custom font

Adafruit_SSD1306 oled;   
#define SSD1306_I2C_ADR   0x3C
int  change = 0;
 
void setup ()
{  
   Serial.begin(9600);
  
   // OLED init 
   delay(100);  // This delay is needed to let the display to initialize
   oled.begin(SSD1306_SWITCHCAPVCC, SSD1306_I2C_ADR);  // Initialize display with the I2C address of 0x3C
   oled.clearDisplay();       // Clear the buffer
   oled.setTextColor(WHITE);  // Set color of the text
   oled.setRotation(0);       // Set orientation. Goes from 0, 1, 2 or 3
   oled.setTextWrap(false);   // By default, long lines of text are set to automatically “wrap” back to the leftmost column.
                              // To override this behavior (so text will run off the right side of the display - useful for
                              // scrolling marquee effects), use setTextWrap(false). The normal wrapping behavior is restored
                              // with setTextWrap(true).
   oled.dim(0);  //Set brightness (0 is maximun and 1 is a little dim)
}

void loop ()
{       
    oled.clearDisplay();  // Clear the display so we can refresh
    oled.setFont(&FreeMono9pt7b);  // Set a custom font
    oled.setTextSize(0);  // Set text size. We are using a custom font so you should always use the text size of 0
    oled.drawRect(0, 0, 128, 63, WHITE);  // Draw rectangle (x,y,width,height,color)
                                          // It draws from the location to down-right
    oled.setCursor(10, 15);     // (x,y)
    oled.println("OLED Test");  // Text or value to print  
    oled.setCursor(20, 50);
    if (change ==0)
      oled.println("14:30:05");
    else 
      oled.println("14:30:06");  
      
    oled.display();  // Print everything we set previously

    delay(1000);
    change = 1 - change;
}