const int LED1 = 2, BPM1 = 40;
const int LED2 = 3, BPM2 = 60;
const int LED3 = 4, BPM3 = 90;
const int LED4 = 5, BPM4 = 110;
const int LED5 = 6, BPM5 = 130;

const int LEDduration = 50;

float delay1 = 60000 / BPM1;
float delay2 = 60000 / BPM2;
float delay3 = 60000 / BPM3;
float delay4 = 60000 / BPM4;
float delay5 = 60000 / BPM5;

class Blinking_LED
{
  private:
  unsigned long previousMillis = 0;
  int isOn = 0;

  public:
  void Blink(int ledPin, float delay, int duration)
  {
  // a function that can blink an LED independent from other functions
  // takes in LED pin number, delay between starts of blinks, duration of each blink
  unsigned long currentMillis = millis();

    if (currentMillis - previousMillis >= delay && isOn == 0)
    {
      digitalWrite(ledPin, HIGH);
      previousMillis = currentMillis;
      isOn = 1;
    }
    else if (currentMillis - previousMillis >= duration && isOn == 1)
    {
      digitalWrite(ledPin, LOW);
      isOn = 0;
    }
  }
};

Blinking_LED LED_obj1;
Blinking_LED LED_obj2;
Blinking_LED LED_obj3;
Blinking_LED LED_obj4;
Blinking_LED LED_obj5;

void setup()
{
  // put your setup code here, to run once:
pinMode(LED1, OUTPUT);
pinMode(LED2, OUTPUT);
pinMode(LED3, OUTPUT);
pinMode(LED4, OUTPUT);
pinMode(LED5, OUTPUT);
}

void loop()
{
  // put your main code here, to run repeatedly:
  LED_obj1.Blink(LED1, delay1, LEDduration);
  LED_obj2.Blink(LED2, delay2, LEDduration);
  LED_obj3.Blink(LED3, delay3, LEDduration);
  LED_obj4.Blink(LED4, delay4, LEDduration);
  LED_obj5.Blink(LED5, delay5, LEDduration);
}