#include <U8g2lib.h>

U8G2_MAX7219_8X8_F_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 18, /* data=*/ 19, /* cs=*/ 5, /* dc=*/ U8X8_PIN_NONE, /* reset=*/ U8X8_PIN_NONE);


const unsigned char smile[] = {
	0x7e, 0x81, 0xa5, 0x81, 0x81, 0xbd, 0x81, 0x7e
};

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");
  u8g2.begin(); // begin function is required for u8g2 library
  u8g2.setContrast(10*16); // set display contrast 0-255
}

void loop() {
  // put your main code here, to run repeatedly:
  u8g2.clearBuffer();	// clear the internal u8g2 memory
  u8g2.drawXBM( 0, 0, 8, 8, smile);
  u8g2.sendBuffer(); // transfer internal memory to the display
  delay(10); // this speeds up the simulation
}