/*

  FontUsage.ino
  
  How to overwrite previous text with a new text.
  How to avoid the buffer clear command.

  Universal 8bit Graphics Library (https://github.com/olikraus/u8g2/)

  Copyright (c) 2016, olikraus@gmail.com
  All rights reserved.

  Redistribution and use in source and binary forms, with or without modification, 
  are permitted provided that the following conditions are met:

  * Redistributions of source code must retain the above copyright notice, this list 
    of conditions and the following disclaimer.
    
  * Redistributions in binary form must reproduce the above copyright notice, this 
    list of conditions and the following disclaimer in the documentation and/or other 
    materials provided with the distribution.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND 
  CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, 
  INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 
  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR 
  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 
  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 
  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 
  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 
  STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 
  ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.  


  Usually, a sequence like this is used:
  u8g2.clearBuffer();					// clear the internal memory
  u8g2.setFont(u8g2_font_ncenB08_tr);	// choose a suitable font
  u8g2.setCursor(0,20)				// set write position
  u8g2.print("Hello World!");			// write something to the internal memory
  u8g2.sendBuffer();					// transfer internal memory to the display
  
  In order to speed up the display content rendering for any modified text,
  we could drop the clearBuffer command and just overwrite the previous string:
  
  u8g2.setFont(u8g2_font_ncenB08_tr);	// choose a suitable font
  u8g2.setCursor(0,20)				// set write position
  u8g2.print("hello there");			// write something to the internal memory
  u8g2.sendBuffer();					// transfer internal memory to the display

  This will only work if:
  - Background is drawn
  - All gylphs have the same height
  Additionally some extra spaces are required of the new text is shorter than the
  previous one.
  
  To draw the background: use font mode 0
  To ensure that all glyphs have the same height, use h or m fonts.
  
  u8g2.setFontMode(0);				// write solid glyphs
  u8g2.setFont(u8g2_font_ncenB08_hr);	// choose a suitable h font
  u8g2.setCursor(0,20)				// set write position
  u8g2.print("hello there  ");			// use extra spaces here
  u8g2.sendBuffer();					// transfer internal memory to the display
  

*/

#include <Arduino.h>
#include <U8g2lib.h>

#ifdef U8X8_HAVE_HW_SPI
#include <SPI.h>
#endif
#ifdef U8X8_HAVE_HW_I2C
#include <Wire.h>
#endif

/*
  U8glib Example Overview:
    Frame Buffer Examples: clearBuffer/sendBuffer. Fast, but may not work with all Arduino boards because of RAM consumption
    Page Buffer Examples: firstPage/nextPage. Less RAM usage, should work with all Arduino boards.
    U8x8 Text Only Example: No RAM usage, direct communication with display controller. No graphics, 8x8 Text only.
    
*/

// Please UNCOMMENT one of the contructor lines below
// U8g2 Contructor List (Frame Buffer)
// The complete list is available here: https://github.com/olikraus/u8g2/wiki/u8g2setupcpp
// Please update the pin numbers according to your setup. Use U8X8_PIN_NONE if the reset pin is not connected
//U8G2_NULL u8g2(U8G2_R0);	// null device, a 8x8 pixel display which does nothing
//U8G2_SSD1306_128X64_NONAME_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_SSD1306_128X64_NONAME_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 12, /* dc=*/ 4, /* reset=*/ 6);	// Arduboy (Production, Kickstarter Edition)
//U8G2_SSD1306_128X64_NONAME_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_SSD1306_128X64_NONAME_F_3W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* reset=*/ 8);
//U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);
//U8G2_SSD1306_128X64_ALT0_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);   // same as the NONAME variant, but may solve the "every 2nd line skipped" problem
//U8G2_SSD1306_128X64_NONAME_F_SW_I2C u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* reset=*/ 8);
//U8G2_SSD1306_128X64_NONAME_F_SW_I2C u8g2(U8G2_R0, /* clock=*/ SCL, /* data=*/ SDA, /* reset=*/ U8X8_PIN_NONE);   // All Boards without Reset of the Display
//U8G2_SSD1306_128X64_NONAME_F_SW_I2C u8g2(U8G2_R0, /* clock=*/ 16, /* data=*/ 17, /* reset=*/ U8X8_PIN_NONE);   // ESP32 Thing, pure SW emulated I2C
//U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE, /* clock=*/ 16, /* data=*/ 17);   // ESP32 Thing, HW I2C with pin remapping
//U8G2_SSD1306_128X64_NONAME_F_6800 u8g2(U8G2_R0, 13, 11, 2, 3, 4, 5, 6, A4, /*enable=*/ 7, /*cs=*/ 10, /*dc=*/ 9, /*reset=*/ 8);
//U8G2_SSD1306_128X64_NONAME_F_8080 u8g2(U8G2_R0, 13, 11, 2, 3, 4, 5, 6, A4, /*enable=*/ 7, /*cs=*/ 10, /*dc=*/ 9, /*reset=*/ 8);
//U8G2_SSD1306_128X64_VCOMH0_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);	// same as the NONAME variant, but maximizes setContrast() range
//U8G2_SSD1306_128X64_ALT0_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);	// same as the NONAME variant, but may solve the "every 2nd line skipped" problem
//U8G2_SH1106_128X64_NONAME_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_SH1106_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);
//U8G2_SH1106_128X64_VCOMH0_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);		// same as the NONAME variant, but maximizes setContrast() range
//U8G2_SH1106_128X64_WINSTAR_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);		// same as the NONAME variant, but uses updated SH1106 init sequence
//U8G2_SH1107_64X128_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_SH1107_128X128_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_SH1107_128X128_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ 8);
//U8G2_SH1107_SEEED_96X96_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_SSD1306_128X32_UNIVISION_F_SW_I2C u8g2(U8G2_R0, /* clock=*/ 21, /* data=*/ 20, /* reset=*/ U8X8_PIN_NONE);   // Adafruit Feather M0 Basic Proto + FeatherWing OLED
//U8G2_SSD1306_128X32_UNIVISION_F_SW_I2C u8g2(U8G2_R0, /* clock=*/ SCL, /* data=*/ SDA, /* reset=*/ U8X8_PIN_NONE);   // Adafruit Feather ESP8266/32u4 Boards + FeatherWing OLED
//U8G2_SSD1306_128X32_UNIVISION_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);  // Adafruit ESP8266/32u4/ARM Boards + FeatherWing OLED
//U8G2_SSD1306_128X32_UNIVISION_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE, /* clock=*/ SCL, /* data=*/ SDA);   // pin remapping with ESP8266 HW I2C
//U8G2_SSD1306_64X48_ER_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);   // EastRising 0.66" OLED breakout board, Uno: A4=SDA, A5=SCL, 5V powered
//U8G2_SSD1306_64X32_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE); 
//U8G2_SSD1306_64X32_1F_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE); 
//U8G2_SSD1306_96X16_ER_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);   // EastRising 0.69" OLED
//U8G2_SSD1322_NHD_256X64_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);	// Enable U8G2_16BIT in u8g2.h
//U8G2_SSD1322_NHD_256X64_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);	// Enable U8G2_16BIT in u8g2.h
//U8G2_SSD1322_NHD_128X64_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_SSD1322_NHD_128X64_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_SSD1325_NHD_128X64_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8); 
//U8G2_SSD1325_NHD_128X64_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);	
//U8G2_SSD1326_ER_256X32_1_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);         // experimental driver for ER-OLED018-1
//U8G2_SSD1327_SEEED_96X96_F_SW_I2C u8g2(U8G2_R0, /* clock=*/ SCL, /* data=*/ SDA, /* reset=*/ U8X8_PIN_NONE);	// Seeedstudio Grove OLED 96x96
//U8G2_SSD1327_SEEED_96X96_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);	// Seeedstudio Grove OLED 96x96
//U8G2_SSD1327_MIDAS_128X128_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_SSD1327_MIDAS_128X128_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_SSD1329_128X96_NONAME_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_SSD1329_128X96_NONAME_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_SSD1305_128X32_NONAME_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_SSD1305_128X32_NONAME_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_SSD1309_128X64_NONAME0_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);  
//U8G2_SSD1309_128X64_NONAME0_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);  
//U8G2_SSD1309_128X64_NONAME2_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);  
//U8G2_SSD1309_128X64_NONAME2_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);  
//U8G2_LD7032_60X32_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 11, /* data=*/ 12, /* cs=*/ 9, /* dc=*/ 10, /* reset=*/ 8);	// SW SPI Nano Board
//U8G2_LD7032_60X32_F_4W_SW_I2C u8g2(U8G2_R0, /* clock=*/ 11, /* data=*/ 12, /* reset=*/ U8X8_PIN_NONE);	// NOT TESTED!
//U8G2_UC1701_EA_DOGS102_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_UC1701_EA_DOGS102_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_PCD8544_84X48_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);  // Nokia 5110 Display
//U8G2_PCD8544_84X48_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8); 		// Nokia 5110 Display
//U8G2_PCF8812_96X65_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);	// Could be also PCF8814
//U8G2_PCF8812_96X65_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);						// Could be also PCF8814
//U8G2_HX1230_96X68_F_3W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* reset=*/ 8);
//U8G2_HX1230_96X68_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_KS0108_128X64_F u8g2(U8G2_R0, 8, 9, 10, 11, 4, 5, 6, 7, /*enable=*/ 18, /*dc=*/ 17, /*cs0=*/ 14, /*cs1=*/ 15, /*cs2=*/ U8X8_PIN_NONE, /* reset=*/  U8X8_PIN_NONE); 	// Set R/W to low!
//U8G2_KS0108_ERM19264_F u8g2(U8G2_R0, 8, 9, 10, 11, 4, 5, 6, 7, /*enable=*/ 18, /*dc=*/ 17, /*cs0=*/ 14, /*cs1=*/ 15, /*cs2=*/ 16, /* reset=*/  U8X8_PIN_NONE); 	// Set R/W to low!
//U8G2_ST7920_192X32_F_8080 u8g2(U8G2_R0, 8, 9, 10, 11, 4, 5, 6, 7, /*enable=*/ 18, /*cs=*/ U8X8_PIN_NONE, /*dc=*/ 17, /*reset=*/ U8X8_PIN_NONE);
//U8G2_ST7920_192X32_F_SW_SPI u8g2(U8G2_R0, /* clock=*/ 18 /* A4 */ , /* data=*/ 16 /* A2 */, /* CS=*/ 17 /* A3 */, /* reset=*/ U8X8_PIN_NONE);
//U8G2_ST7920_128X64_F_8080 u8g2(U8G2_R0, 8, 9, 10, 11, 4, 5, 6, 7, /*enable=*/ 18 /* A4 */, /*cs=*/ U8X8_PIN_NONE, /*dc/rs=*/ 17 /* A3 */, /*reset=*/ 15 /* A1 */);	// Remember to set R/W to 0 
//U8G2_ST7920_128X64_F_SW_SPI u8g2(U8G2_R0, /* clock=*/ 18 /* A4 */ , /* data=*/ 16 /* A2 */, /* CS=*/ 17 /* A3 */, /* reset=*/ U8X8_PIN_NONE);
//U8G2_ST7920_128X64_F_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* CS=*/ 10, /* reset=*/ 8);
//U8G2_ST7920_128X64_F_HW_SPI u8g2(U8G2_R0, /* CS=*/ 10, /* reset=*/ 8);
//U8G2_ST7565_EA_DOGM128_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_ST7565_EA_DOGM128_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_ST7565_64128N_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_ST7565_64128N_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_ST7565_EA_DOGM132_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ U8X8_PIN_NONE);	// DOGM132 Shield
//U8G2_ST7565_EA_DOGM132_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ U8X8_PIN_NONE);	// DOGM132 Shield
//U8G2_ST7565_ZOLEN_128X64_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_ST7565_ZOLEN_128X64_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_ST7565_LM6059_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);		// Adafruit ST7565 GLCD
//U8G2_ST7565_LM6059_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);		// Adafruit ST7565 GLCD
//U8G2_ST7565_ERC12864_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_ST7565_ERC12864_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_ST7565_NHD_C12832_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_ST7565_NHD_C12832_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_ST7565_NHD_C12864_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_ST7565_NHD_C12864_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_ST7567_PI_132X64_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 7, /* dc=*/ 9, /* reset=*/ 8);  // Pax Instruments Shield, LCD_BL=6
//U8G2_ST7567_PI_132X64_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 7, /* dc=*/ 9, /* reset=*/ 8);  // Pax Instruments Shield, LCD_BL=6
//U8G2_ST7567_JLX12864_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 7, /* dc=*/ 9, /* reset=*/ 8);  
//U8G2_ST7567_JLX12864_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 7, /* dc=*/ 9, /* reset=*/ 8);  
//U8G2_ST75256_JLX172104_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_ST75256_JLX172104_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_ST75256_JLX256128_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);	// Enable U8g2 16 bit mode for this display
//U8G2_ST75256_JLX256128_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);		// Enable U8g2 16 bit mode for this display
//U8G2_ST75256_JLX25664_F_2ND_HW_I2C u8g2(U8G2_R0, /* reset=*/ 8);	// Due, 2nd I2C, enable U8g2 16 bit mode for this display
//U8G2_NT7534_TG12864R_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);  
//U8G2_NT7534_TG12864R_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);  
//U8G2_ST7588_JLX12864_F_SW_I2C u8g2(U8G2_R0, /* clock=*/ SCL, /* data=*/ SDA, /* reset=*/ 5);  
//U8G2_ST7588_JLX12864_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ 5);
//U8G2_IST3020_ERC19264_F_6800 u8g2(U8G2_R0, 44, 43, 42, 41, 40, 39, 38, 37,  /*enable=*/ 28, /*cs=*/ 32, /*dc=*/ 30, /*reset=*/ 31); // Connect WR pin with GND
//U8G2_IST3020_ERC19264_F_8080 u8g2(U8G2_R0, 44, 43, 42, 41, 40, 39, 38, 37,  /*enable=*/ 29, /*cs=*/ 32, /*dc=*/ 30, /*reset=*/ 31); // Connect RD pin with 3.3V
//U8G2_IST3020_ERC19264_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);
//U8G2_LC7981_160X80_F_6800 u8g2(U8G2_R0, 8, 9, 10, 11, 4, 5, 6, 7, /*enable=*/ 18, /*cs=*/ 14, /*dc=*/ 15, /*reset=*/ 16); // Connect RW with GND
//U8G2_LC7981_160X160_F_6800 u8g2(U8G2_R0, 8, 9, 10, 11, 4, 5, 6, 7, /*enable=*/ 18, /*cs=*/ 14, /*dc=*/ 15, /*reset=*/ 16); // Connect RW with GND
//U8G2_LC7981_240X128_F_6800 u8g2(U8G2_R0, 8, 9, 10, 11, 4, 5, 6, 7, /*enable=*/ 18, /*cs=*/ 14, /*dc=*/ 15, /*reset=*/ 16); // Connect RW with GND
//U8G2_SED1520_122X32_F u8g2(U8G2_R0, 8, 9, 10, 11, 4, 5, 6, 7, /*dc=*/ A0, /*e1=*/ A3, /*e2=*/ A2, /* reset=*/  A4); 	// Set R/W to low!
//U8G2_T6963_240X128_F_8080 u8g2(U8G2_R0, 8, 9, 10, 11, 4, 5, 6, 7, /*enable=*/ 17, /*cs=*/ 14, /*dc=*/ 15, /*reset=*/ 16); // Connect RD with +5V, FS0 and FS1 with GND
//U8G2_T6963_256X64_F_8080 u8g2(U8G2_R0, 8, 9, 10, 11, 4, 5, 6, 7, /*enable=*/ 17, /*cs=*/ 14, /*dc=*/ 15, /*reset=*/ 16); // Connect RD with +5V, FS0 and FS1 with GND
//U8G2_SED1330_240X128_F_8080 u8g2(U8G2_R0, 8, 9, 10, 11, 4, 5, 6, 7, /*enable=*/ 17, /*cs=*/ 14, /*dc=*/ 15, /*reset=*/ 16); // Connect RD with +5V, FG with GND
//U8G2_SED1330_240X128_F_6800 u8g2(U8G2_R0, 13, 11, 2, 3, 4, 5, 6, A4, /*enable=*/ 7, /*cs=*/ 10, /*dc=*/ 9, /*reset=*/ 8); // A0 is dc pin!
//U8G2_RA8835_NHD_240X128_F_8080 u8g2(U8G2_R0, 8, 9, 10, 11, 4, 5, 6, 7, /*enable=*/ 17, /*cs=*/ 14, /*dc=*/ 15, /*reset=*/ 16); // Connect /RD = E with +5V, enable is /WR = RW, FG with GND, 14=Uno Pin A0
//U8G2_RA8835_NHD_240X128_F_6800 u8g2(U8G2_R0, 8, 9, 10, 11, 4, 5, 6, 7,  /*enable=*/ 17, /*cs=*/ 14, /*dc=*/ 15, /*reset=*/ 16); // A0 is dc pin, /WR = RW = GND, enable is /RD = E
//U8G2_UC1604_JLX19264_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8); 
//U8G2_UC1604_JLX19264_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);  
//U8G2_UC1608_ERC24064_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);  // SW SPI, Due ERC24064-1 Test Setup
//U8G2_UC1608_ERC240120_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8); 
//U8G2_UC1608_240X128_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);  // SW SPI, Due ERC24064-1 Test Setup
//U8G2_UC1610_EA_DOGXL160_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/  U8X8_PIN_NONE);
//U8G2_UC1610_EA_DOGXL160_F_4W_HW_SPI u8g2(U8G2_R0, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/  U8X8_PIN_NONE);
//U8G2_UC1611_EA_DOGM240_F_2ND_HW_I2C u8g2(U8G2_R0, /* reset=*/ 8);	// Due, 2nd I2C, DOGM240 Test Board
//U8G2_UC1611_EA_DOGM240_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);   // Due, SW SPI, DOGXL240 Test Board
//U8G2_UC1611_EA_DOGXL240_F_2ND_HW_I2C u8g2(U8G2_R0, /* reset=*/ 8);	// Due, 2nd I2C, DOGXL240 Test Board
//U8G2_UC1611_EA_DOGXL240_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);   // Due, SW SPI, DOGXL240 Test Board
//U8G2_UC1611_EW50850_F_8080 u8g2(U8G2_R0, 8, 9, 10, 11, 4, 5, 6, 7,  /*enable=*/ 18, /*cs=*/ 3, /*dc=*/ 16, /*reset=*/ 16); // 240x160, Connect RD/WR1 pin with 3.3V, CS is aktive high
//U8G2_UC1638_160X128_F_4W_HW_SPI u8g2(U8G2_R2, /* cs=*/ 2, /* dc=*/ 3, /* reset=*/ 4); 	 // Not tested
//U8G2_SSD1606_172X72_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);		// eInk/ePaper Display
//U8G2_SSD1607_200X200_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);	// eInk/ePaper Display, original LUT from embedded artists
//U8G2_SSD1607_GD_200X200_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);	// Good Display
//U8G2_IL3820_296X128_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);	// WaveShare 2.9 inch eInk/ePaper Display, enable 16 bit mode for this display!
//U8G2_IL3820_V2_296X128_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* cs=*/ 10, /* dc=*/ 9, /* reset=*/ 8);	// ePaper Display, lesser flickering and faster speed, enable 16 bit mode for this display!

// End of constructor list

#define INFO_SCREEN_DELAY 3000

/*
  Linear Congruential Generator (LCG)
  z = (a*z + c) % m;  
  m = 256 (8 Bit)
  
  for period:
  a-1: dividable by 2
  a-1: multiple of 4
  c: not dividable by 2
  
  c = 17
  a-1 = 64 --> a = 65
*/
uint8_t z = 127;	// start value
uint32_t lcg_rnd(void) {
  z = (uint8_t)((uint16_t)65*(uint16_t)z + (uint16_t)17);
  return (uint32_t)z;
}

void setup(void) {
  u8g2.begin();
}

void draw(int is_blank)
{
  int i, j;
  int n;
  char s[4];
  
  for( j = 0; j < 20; j++ )
  {
    // random number
    n = lcg_rnd();
    
    // random string
    for( i = 0; i < 3; i++ )
    {
      s[i] = lcg_rnd()>>3;
      if ( s[i] < 16 )
	s[i] += 'a';
      else
	s[i] += 'A';
    }
    s[3] = '\0';
    
    // print number
    u8g2.setCursor(0,15);
    u8g2.print("Number: ");
    if ( is_blank )
      u8g2.print("       ");
    u8g2.setCursor(70,15);
    u8g2.print(n);
    
    
    // print string
    u8g2.setCursor(0,30);
    u8g2.print("Text: ");
    u8g2.setCursor(70,30);
    u8g2.print(s);
    if ( is_blank )
      u8g2.print("        ");
    
    // make the result visible
    u8g2.sendBuffer();
    
    // delay, so that the user can see the result
    delay(200);
  }
}

void draw_m1_t()
{
  u8g2.clearBuffer();

  u8g2.setFontMode(1);
  u8g2.setFont(u8g2_font_cu12_tr);		

  u8g2.setCursor(0,15);
  u8g2.print(F("setFontMode(1);"));
  u8g2.setCursor(0,30);
  u8g2.print(F("setFont(..._tr);"));
  u8g2.setCursor(0, 55);
  u8g2.print(F("Very Bad"));
    
  u8g2.sendBuffer();
  delay(INFO_SCREEN_DELAY);
  
  u8g2.setFontMode(1);		
  u8g2.setFont(u8g2_font_cu12_tr);		
  u8g2.clearBuffer();					// clear the internal memory once
  draw(0);
}

void draw_m0_t()
{
  u8g2.clearBuffer();
  
  u8g2.setFontMode(1);
  u8g2.setFont(u8g2_font_cu12_tr);		
  
  u8g2.setCursor(0,15);
  u8g2.print(F("setFontMode(0);"));
  u8g2.setCursor(0,30);
  u8g2.print(F("setFont(.._tr);"));
  u8g2.setCursor(0, 55);
  u8g2.print(F("Wrong"));
  
  u8g2.sendBuffer();
  delay(INFO_SCREEN_DELAY);
  
  u8g2.setFontMode(0);
  u8g2.setFont(u8g2_font_cu12_tr);		  
  u8g2.clearBuffer();					// clear the internal memory once
  draw(0);
}

void draw_m1_h()
{
  u8g2.clearBuffer();
  
  u8g2.setFontMode(1);
  u8g2.setFont(u8g2_font_cu12_tr);		
  
  u8g2.setCursor(0,15);
  u8g2.print(F("setFontMode(0);"));
  u8g2.setCursor(0,30);
  u8g2.print(F("setFont(.._hr);"));  
  u8g2.setCursor(0, 55);
  u8g2.print(F("Still bad"));
  
  u8g2.sendBuffer();
  delay(INFO_SCREEN_DELAY);
  
  u8g2.setFontMode(1);
  u8g2.setFont(u8g2_font_cu12_hr);		
  u8g2.clearBuffer();					// clear the internal memory once
  draw(0);
}

void draw_m0_h()
{
  u8g2.clearBuffer();
  
  u8g2.setFontMode(1);
  u8g2.setFont(u8g2_font_cu12_tr);		
  
  u8g2.setCursor(0,15);
  u8g2.print(F("setFontMode(0);"));
  u8g2.setCursor(0,30);
  u8g2.print(F("setFont(.._hr);"));  
  u8g2.setCursor(0, 55);
  u8g2.print(F("Almost ok"));
  
  u8g2.sendBuffer();
  delay(INFO_SCREEN_DELAY);
  
  u8g2.setFontMode(0);
  u8g2.setFont(u8g2_font_cu12_hr);		
  u8g2.clearBuffer();					// clear the internal memory once
  draw(0);
}

void draw_m0_h_with_extra_blank()
{
  u8g2.clearBuffer();
  
  u8g2.setFontMode(1);
  u8g2.setFont(u8g2_font_cu12_tr);		
  
  u8g2.setCursor(0,15);
  u8g2.print(F("setFontMode(0);"));
  u8g2.setCursor(0,30);
  u8g2.print(F("setFont(.._hr);"));  
  u8g2.setCursor(0, 55);
  u8g2.print(F("Extra blank --> Ok"));
  
  u8g2.sendBuffer();
  delay(INFO_SCREEN_DELAY);
  
  u8g2.setFontMode(0);
  u8g2.setFont(u8g2_font_cu12_hr);		
  u8g2.clearBuffer();					// clear the internal memory once
  draw(1);
}


void loop(void) {

  // This problem applies only to full buffer mode
  u8g2.clearBuffer();  
  u8g2.setFontMode(1);
  u8g2.setFont(u8g2_font_cu12_tr);		  
  u8g2.setCursor(0,15);
  u8g2.print(F("Problems with"));
  u8g2.setCursor(0,30);
  u8g2.print(F("full buffer mode"));
  u8g2.setCursor(0,45);
  u8g2.print(F("and skipped clear."));
  u8g2.sendBuffer();
  delay(INFO_SCREEN_DELAY);
  

  draw_m1_t();			// fontmode 1, t font --> wrong
  draw_m1_h();			// fontmode 1, h font --> wrong
  draw_m0_t();			// fontmode 0, t font --> wrong
  draw_m0_h();			// fontmode 1, h font --> ok
  draw_m0_h_with_extra_blank();	// fontmode 1, h font with extra blank --> correct
  delay(1000);  
}

