#include<Arduino.h>

#include<U8g2lib.h>

#ifdefU8X8_HAVE_HW_SPI

#include<SPI.h>

#endif

#ifdefU8X8_HAVE_HW_I2C

#include<Wire.h>

#endif

#defineSDA_PIN5

#defineSCL_PIN6

U8G2_SSD1306_72X40_ER_F_HW_I2Cu8g2(U8G2_R0,/* reset=*/U8X8_PIN_NONE);// EastRising 0.42" OLED

#defineINFO_SCREEN_DELAY3000

uint8_tz =127;// start value

uint32_tlcg_rnd(void){

z =(uint8_t)((uint16_t)65*(uint16_t)z +(uint16_t)17);

return(uint32_t)z;

}

voidsetup(void){

Wire.begin(SDA_PIN, SCL_PIN);

u8g2.begin();

}

voiddraw(intis_blank)

{

inti, j;

intn;

chars[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);

}

}

voiddraw_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);

}

voiddraw_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);

}

voiddraw_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);

}

voiddraw_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);

}

voiddraw_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);

}

voidloop(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);

}