stepper motor with a4988 driver and serial controlled

/* setup to control a stepper motor with a A4988 polulu driver and Serial controlled
 Made by Luc Francoeur (push28@gmail.com). As usual feel free to contact me if you
 have any question

direction       step precision      controller          reset       step count
F = forward     F = full            e= enabled          R=reset     data[4,5,6,7]
R = reverse     H= half             d= disabled         N=null
                Q= quarter          S= sleep
                E= eight
                S= sixteen

            1.8 degree per step at full / 200steps
            0,9 degree per step at half / 400steps
            0,45 degree per step at quarter / 800steps
            0,225 degree per step at eight / 1600steps
            0,1025degree per step at sixteenth / 3200steps
*/

#include <Wire.h>;
char ds[8];
char buffer[25];
const int stepPin = 2;
const int dirPin = 3;
const int ms1 = 11;
const int ms2 = 12;
const int ms3 = 13;
const int enable = A1;
const int reset = A2;
const int sleep = A3;
int stepcount = 0;
int var = 0;

void setup() {
  pinMode(stepPin, OUTPUT);
  pinMode(dirPin, OUTPUT);
  pinMode(ms1, OUTPUT);
  pinMode(ms2, OUTPUT);
  pinMode(ms3, OUTPUT);
  pinMode(enable, OUTPUT);
  pinMode(reset, OUTPUT);
  digitalWrite(reset,LOW);
  digitalWrite(enable,HIGH);
  digitalWrite(sleep,LOW);

  Serial.begin(19200); // Speed of serial port
  Serial.flush();
  Wire.begin(0x02); // join i2c bus (address optional for master)
  Wire.onRequest(requestEvent); // register event

}


void loop() {

  while (var < stepcount) {
    digitalWrite(stepPin, HIGH);
    delay(3);
    digitalWrite(stepPin, LOW);
    var++;
  }

  if (Serial.available() > 0) {
    byte index = 0;
    delay(100); // let the buffer fill up
    byte numChar = Serial.available();
    if (numChar > 20) {
      numChar = 20;
    }
    while (numChar--) {
      buffer[index++] = Serial.read();
    }
    splitString(buffer);
  }

}

void splitString(char* data) {

  char * parameter;
  parameter = strtok (data, " ,");
  while (parameter != NULL) {
    setStepper(parameter);
    calcStepper(parameter);
    parameter = strtok (NULL, " ,");
  }// Clear the text and serial buffers
  for (byte x = 0; x < 20; x++) {
    buffer[x] = '\0';
  }
  Serial.flush();
}


void setStepper(char *data) {

  ds[0] = data[0];
  ds[1] = data[1];
  ds[2] = data[2];
  ds[3] = data[3];
  ds[4] = data[4];
  ds[5] = data[5];
  ds[6] = data[6];
  ds[7] = data[7];

  if ((data[0] == 'F') || (data[0] == 'f')) { //clockwise rotation
    digitalWrite(dirPin, LOW);
    Serial.flush();
    Serial.print("clockwise rotation, ");
  }

  if ((data[0] == 'R') || (data[0] == 'r')) { //counter-clockwise rotation
    digitalWrite(dirPin, HIGH);
    Serial.print("counter rotation, ");
  }


  if ((data[1] == 'F') || (data[1] == 'f')) { //step precision Full
    digitalWrite(ms1, LOW);
    digitalWrite(ms2, LOW);
    digitalWrite(ms3, LOW);
    Serial.print("full-step, ");
  }

  if ((data[1] == 'H') || (data[1] == 'h')) { //step precision Half
    digitalWrite(ms1, HIGH);
    digitalWrite(ms2, LOW);
    digitalWrite(ms3, LOW);
    Serial.print("half-step, ");
  }

  if ((data[1] == 'Q') || (data[1] == 'q')) { //step precision Quarter
    digitalWrite(ms1, LOW);
    digitalWrite(ms2, HIGH);
    digitalWrite(ms3, LOW);
    Serial.print("quarter-step, ");
  }

  if ((data[1] == 'E') || (data[1] == 'e')) { //step precision Eight
    digitalWrite(ms1, HIGH);
    digitalWrite(ms2, HIGH);
    digitalWrite(ms3, LOW);
    Serial.print("eight-step, ");
  }

  if ((data[1] == 'S') || (data[1] == 's')) { //step precision Sixteenth
    digitalWrite(ms1, HIGH);
    digitalWrite(ms2, HIGH);
    digitalWrite(ms3, HIGH);
    Serial.print("sixteenth-step, ");
  }


  if ((data[2] == 'E') || (data[2] == 'e')) { //controller Enabled
    digitalWrite(enable, LOW);
    digitalWrite(sleep,HIGH);
    Serial.print("controller Enabled, ");
  }

  if ((data[2] == 'D') || (data[2] == 'd')) { //controller Disabled
    digitalWrite(enable, HIGH);
    digitalWrite(sleep,HIGH);
    Serial.print("controller Disabled, ");
  }

  if ((data[2] == 'S') || (data[2] == 's')) { //controller in Sleep Mode
    digitalWrite(enable, LOW);
    digitalWrite(sleep,LOW);
    Serial.print("controller Sleeping, ");
  }


  if ((data[3] == 'R') || (data[3] == 'r')) { //Reset Enabled
    digitalWrite(reset, LOW);
    delay(50);
    digitalWrite(reset,HIGH);
    Serial.println("resetting, ");
  }

  if ((data[3] == 'N') || (data[3] == 'n')) { //Reset Disabled
    digitalWrite(reset, HIGH);
    Serial.println("reset Disabled, ");
  }
}


void requestEvent() {
  Wire.write(ds); // respond with message of 6 bytes
  // as expected by master
}


void calcStepper(char *ds) {
  Serial.flush();
  int Ans = strtol(ds + 4, NULL, 10);
  Ans = constrain(Ans, 0, 6400);
  stepcount = Ans;
  Serial.print("initiating ");
  Serial.print(Ans);
  Serial.println(" steps rotation");
  Serial.print("DataStream received by Controller: ");
  Serial.println(ds);
  var = 0;
}