How would I get the delayMicroseconds() from an RPM value?

Projects Programming
1

I'm trying to make something like this: LEXUS LFA V10 1LRGUE (even fire) firing order AudioVisual demonstration 1 2 3 4 7 8 9 10 5 6 - YouTube, but I dont know how I would convert an RPM value (like 8000) to microseconds for delayMicroseconds(), how would I do this?

2

8000 RPM is 133.3 rotations per second.

Seconds per rotation is 1/133.3 = 0.0075 seconds

3

How would I convert that in code format? Also, I was talking about microseconds, not seconds.

4

There are 1 million microseconds in one second.

5

You can't use a delay for timing unless you know how long the rest of the code takes. Better to use 'micros()' for timing.

float RPM = 8000.0;
const unsigned Cylinders = 10;
unsigned CylinderIndex = 0;

// LED pins for cylinders in firing order:
// 1 2 3 4 7 8 9 10 5 6
const byte CylinderPins[Cylinders] = {2, 3, 4, 5, 6, 7, 8, 9, 10, 11};

void setup()
{
  for (size_t i = 0; i < Cylinders; i++)
  {
    digitalWrite(CylinderPins[i], LOW);
    pinMode(CylinderPins[i], OUTPUT);
  }
}

void loop()
{
  float microsecondsPerRevolution = 1000000.0 / (RPM * 60);
  unsigned long microsecondsPerCylinder = microsecondsPerRevolution / Cylinders;

  unsigned long currentMicros = micros();
  static unsigned long lastCylinderTime = 0;
  if (currentMicros - lastCylinderTime >= microsecondsPerCylinder)
  {
    // Edit: OOPS.  I forgot this line.  Again.
    lastCylinderTime = currentMicros;

    digitalWrite(CylinderPins[CylinderIndex], LOW);
    CylinderIndex++;
    if (CylinderIndex >= Cylinders)
      CylinderIndex = 0;
    digitalWrite(CylinderPins[CylinderIndex], HIGH);
  }
}