I'm currently trying to build a 3d scanner with a garmin v3, sparkfun motors, a4988, and an Arduino Uno. However, currently, my sparkfun stepper motors, which are driven by A4988, switch directions every step. I'm not sure why this issue occurs, and sometimes the stepper motors steps properly, but 95% of the time, the stepper switches direction every step. I'm currently micro stepping by 1/16, but when the oscillation occurs, it appears to be taken over 1 step every oscillation cycle. Here is a link to a video of this issue:

Here is my code

#include
#include

LIDARLite myLidarLite;
const int dirPinV = 2;  // Direction
const int stepPinV = 3; // Step
const int dirPinH = 4;  // Direction
const int stepPinH = 5; // Step

// Motor steps per rotation

void setup() {
  Serial.begin(115200);
  myLidarLite.begin(0, true); // Set configuration to default and I2C to 400 kHz
  myLidarLite.configure(0); // Change this number to try out alternate configurations

  // Setup the pins as Outputs
  pinMode(stepPinV,OUTPUT);
  pinMode(dirPinV,OUTPUT);
  pinMode(stepPinH,OUTPUT);
  pinMode(dirPinH,OUTPUT);

  pinMode(8,OUTPUT);
  pinMode(9,OUTPUT);
  pinMode(10,OUTPUT);

  pinMode(11,OUTPUT);
  pinMode(12,OUTPUT);
  pinMode(13,OUTPUT);

  digitalWrite(8,HIGH);
  digitalWrite(9,HIGH);
  digitalWrite(10,HIGH);

  digitalWrite(11,HIGH);
  digitalWrite(12,HIGH);
  digitalWrite(13,HIGH);

}
void loop() {
  int maxStepV = 45*16;
  int stepV = 1;

  int maxStepH = 60*16;
  int stepH = 1;
  for (int x = 0; x < maxStepH; x = x + stepH*2)
  {
    // Set motor direction clockwise
    digitalWrite(dirPinV,HIGH);
    // Spin vertical
    for(int v = 0; v <= maxStepV; v= v + stepV) {
      digitalWrite(stepPinV,HIGH);
      delayMicroseconds(500);
      digitalWrite(stepPinV,LOW);
      delayMicroseconds(500);
      Serial.println(myLidarLite.distance(false));
    }
    // Pause for one second
    delay(1000);

    // Spin horizontal
    digitalWrite(dirPinH,HIGH);
    for(int hstep = 0; hstep <= stepH; hstep= hstep + stepH) {
      digitalWrite(stepPinH,HIGH);
      delayMicroseconds(10000);
      digitalWrite(stepPinH,LOW);
      delayMicroseconds(10000);
    }
    myLidarLite.distance(true);

    // Pause for one second
    delay(1000);

    // spin vertical
    digitalWrite(dirPinV,LOW);
    // Spin motor two rotations quickly
    for(int v = 0; v <= maxStepV; v= v + stepV) {
      digitalWrite(stepPinV,HIGH);
      delayMicroseconds(500);
      digitalWrite(stepPinV,LOW);
      delayMicroseconds(500);
      Serial.println(myLidarLite.distance(false));
    }
    // Pause for one second
    delay(1000);

    // Spin horizontal
    digitalWrite(dirPinH,HIGH);
    for(int hstep = 0; hstep <= stepH; hstep= hstep + stepH) {
      digitalWrite(stepPinH,HIGH);
      delayMicroseconds(10000);
      digitalWrite(stepPinH,LOW);
      delayMicroseconds(10000);
    }
    myLidarLite.distance(true);
    // Pause for one second
    delay(1000);
  }
}