#include <AccelStepper.h>
AccelStepper stepper[] = {
  {1, 3,2},
  {1, 5,4},
  {1, 7,6},
  {1, 9,8},
};
constexpr byte stepperCount = sizeof(stepper)/sizeof(stepper[0]);
constexpr byte joystickPin[] = {A0, A1, A2, A3};

void setup() {
  Serial.begin(9600);
  for ( byte i = 0; i < stepperCount; i++ ) {
    stepper[i].setMaxSpeed(500);
    stepper[i].setAcceleration(250);
  }
}

void loop() {
  for ( byte i = 0;  i < stepperCount; i++ ) {
    int joystickValue = analogRead(joystickPin[i]);
    int deviation = joystickValue - 512;
    if (abs(deviation) > 10) {
      int speed = map(deviation, -512, 512, -500, 500);
      Serial.print(speed);
      stepper[i].setSpeed(speed);
    } else {
      stepper[i].setSpeed(0);
    }
    stepper[i].runSpeed();
  }
}