#include <Wire.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 16, 2); // Set I2C address and display size

const int crankPin = 9;  // Crank sensor output pin
const int camPin = 10;   // Cam sensor output pin
const int potPin = A0;   // Potentiometer input pin

void setup() {
  pinMode(crankPin, OUTPUT);
  pinMode(camPin, OUTPUT);
  pinMode(potPin, INPUT);
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("RPM:CRANK");
}

void loop() {
  int potValue = analogRead(potPin);
  int pulseWidth = map(potValue, 0, 1023, 10, 90);

  // Crank sensor signal
  float crankPeriod = 1000.0 / 20.0; // 20 Hz
  float crankHighTime = crankPeriod * (pulseWidth / 100.0);
  digitalWrite(crankPin, HIGH);
  delayMicroseconds(crankHighTime);
  digitalWrite(crankPin, LOW);
  delayMicroseconds(crankPeriod - crankHighTime);

  // Cam sensor signal
  float camPeriod = 1000.0 / 10.0; // 10 Hz
  float camHighTime = camPeriod * (pulseWidth / 100.0);
  digitalWrite(camPin, HIGH);
  delayMicroseconds(camHighTime);
  digitalWrite(camPin, LOW);
  delayMicroseconds(camPeriod - camHighTime);

  // Calculate RPM
  int rpm = map(pulseWidth, 10, 90, 500, 6000);

  // Display RPM
  lcd.setCursor(0, 1);
  lcd.print(rpm);
  lcd.print(" RPM");
  delay(100);
}