#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>


#define SCREEN_WIDTH 128 // OLED display width, in pixels // tambahan
#define SCREEN_HEIGHT 64 // OLED display height, in pixels  //tambahan
#define OLED_RESET 4
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);  //tambahan
//Adafruit_SSD1306 display(OLED_RESET);  // original


const int IR_PIN = 2;  // IR sensor input pin

volatile unsigned int counter = 0;  // Counter variable for revolutions
unsigned long previousMillis = 0;  // Variable to store previous time
unsigned int rpm = 0;  // Variable to store RPM value

void IRinterrupt() {
  counter++;
}

void setup() {
  pinMode(IR_PIN, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(IR_PIN), IRinterrupt, FALLING);

  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  display.display();
  delay(2000);
  display.clearDisplay();
  display.setTextSize(2);
  display.setTextColor(SSD1306_WHITE);
  //display.setCursor(0, 0);
  //display.println("TEG");
  //display.display();
  //delay(2000);
  display.clearDisplay();
  display.setTextSize(2);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(30, 0);  //modifikasi
  display.println("Speed");  //modifikasi
  display.setCursor(20, 20);  //modifikasi
  display.println("Checker"); //modifikasi
  display.display();
  delay(2000);
}

void loop() {
  unsigned long currentMillis = millis();

  if (currentMillis - previousMillis >= 1000) {
    detachInterrupt(digitalPinToInterrupt(IR_PIN));
    rpm = (counter / 2) * 60;  // Calculate RPM
    counter = 0;
    attachInterrupt(digitalPinToInterrupt(IR_PIN), IRinterrupt, FALLING);
    previousMillis = currentMillis;

    display.clearDisplay();
    display.setTextSize(1);
    display.setCursor(0, 30);
    display.print("SPEED: ");
    display.setCursor(100, 30);
    display.print("Km/h ");
    display.setCursor(0, 45);
    display.print("RPM  : ");
    display.println(rpm);
    display.display();
  }
}