int ledPin = 4;  // Pin connected to the LED
unsigned long previousMillis = 0;  // Stores the time when LED was last toggled
long blinkInterval = 1000;  // Blink interval in milliseconds (initial value)

void setup() {
  pinMode(ledPin, OUTPUT);  // Set LED pin as output
  // (Add any other setup code for your other functionalities here)
}

void loop() {
  unsigned long currentMillis = millis();  // Get current time

  // Check if it's time to blink the LED
  if (currentMillis - previousMillis >= blinkInterval) {
    previousMillis = currentMillis;  // Update the previous time
    digitalWrite(ledPin, !digitalRead(ledPin));  // Toggle the LED state
  }

  // (Place the code for your other functionalities here)
  // They will run uninterrupted as long as they don't take too long
}

// Function to change the blink interval
void setBlinkInterval(long newInterval) {
  blinkInterval = newInterval;
}