Choosing right motor shield (& other components)

Using Arduino Motors, Mechanics, Power and CNC
12

Robin2:
What is the difference between your non-working program and the program you used to prove that the motor works? The problem will be somewhere in the difference.

The code that made the motor spin:

void loop(){
  //Enables the motor direction to move in a certain direction.
  digitalWrite(dirPin,LOW);
  //Makes 200 Pulses for making one full cycle (1.8 degree stepper).
  for(int x = 0; x < 200; x++){
    digitalWrite(stepPin,HIGH); 
    delayMicroseconds(500);
    digitalWrite(stepPin,LOW); 
    delayMicroseconds(500);
}
}

Now I wanted to add the functionality of it being RPM controlled between 0 and 100 RPM so I changed it to:

void loop(){
  Pot = analogRead(A1);
  RPM =(Pot*100L)/1023;

  //Enables the motor direction to move in a certain direction.
  digitalWrite(dirPin,LOW);
  //Makes 200 Pulses for making one full cycle (1.8 degree stepper).
  for(int x = 0; x < 200; x++){
    digitalWrite(stepPin,HIGH); 
    motor =((((RPM*1000000)/60)/200)/2);
    delayMicroseconds(motor);
    digitalWrite(stepPin,LOW); 
    motor =((((RPM*1000000)/60)/200)/2);
    delayMicroseconds(motor);
}
}

I checked the RPM value with serial.print and it varies between 0 and 100 nicely when turning the potentiometer. I am sure the reason the motor doesn't spin has to do with the code after the RPM has been defined. Any pointers or tips on standard code to control a motors RPM? Having a hard time to find something similar and useful on the forum.

Yours sincerely,

Driez