// For: https://forum.arduino.cc/t/oled-display-using-u8x8-library-hardware-vs-software-spi/1053666/
// This Wokwi project: https://wokwi.com/projects/348382129617371731

#include <SPI.h>
#include <U8g2lib.h>

#define MOSI  11
#define DC    9
#define SCK   13
#define CS    14

#define SAMPLE_TIME 1000  //  1 second = 1000 ms

U8X8_SSD1306_128X64_NONAME_4W_HW_SPI u8x8(CS, DC);
// U8X8_SSD1306_128X64_NONAME_4W_SW_SPI u8x8(SCK, MOSI, CS, DC);
// U8X8_SSD1306_128X64_NONAME_HW_I2C u8x8(U8X8_PIN_NONE);
// U8X8_SSD1306_128X64_NONAME_SW_I2C u8x8(SCL, SDA, U8X8_PIN_NONE);

unsigned int loopCounter = 0;
unsigned long startTime;

void setup(void) {
  Serial.begin(115200);
  u8x8.begin();
  u8x8.setFont(u8x8_font_chroma48medium8_r);

  startTime = millis();
}

void loop(void) {
  unsigned long currentTime = millis();
  loopCounter++;
  
  // speed test by writing text to the display
  u8x8.drawString(0, 0, "Hello World");

  // one second millis timer
  if (currentTime - startTime >= SAMPLE_TIME) {
    startTime = currentTime;
    Serial.println( loopCounter);
    loopCounter = 0;
  }
}