How to use MDBT42Q with Nema17 stepper motors?

Hey, y'all. I have the MDBT42Q breakout board and I am trying to create a simple example where a button is pressed and the stepper motor rotates for like a half revolution.

I am using the A4988 drivers and I have managed to connect and continuously rotate the stepper motor using this sample code:

const PIN_ENABLE = D14; 
const PIN_STEP = D13;
const PIN_DIRECTION = D12;

digitalWrite(PIN_DIRECTION, direction);
digitalWrite(PIN_ENABLE, enabled);

analogWrite(PIN_STEP, 0.9, {freq: 100});

I am not sure though how is it possible to count the steps per revolution and how frequency is related to rotation and time.
Thanks in advance for your help :)