Automated Measurement Turntable Controlled by REW

#define slpPin 4
#define dirPin 2
#define stepPin 3

#define clockwise 0x1
#define counterclockwise 0x0
#define stepsPerDeg 160
#define secPerRot 20
#define delay 20*17.36

const byte numChars = 32;
char alphaChar;
uint8_t dir;
char digitsChars[4];
int deg;
bool newData = false;

void setup() {
  Serial.begin(9600);
  Serial.println("<ttready>");
}

void loop() {
  recvSerialInput();
  onNewData();
}

void recvSerialInput() {
  static boolean recvInProgress = false;

  static byte iRd = 0;
  char startMarker = '<';
  char endMarker = '>';
  char rc;

  while (Serial.available() > 0 && newData == false) {
    rc = Serial.read();

    if (recvInProgress == true) {
      if (rc != endMarker) {
        switch (rc) {
          case 'a':
            dir = clockwise;
            break;
          case 'd':
            dir = counterclockwise;
            break;
          default:
            if (isDigit(rc)) {
              digitsChars[iRd] = rc;
              iRd++;
              if (iRd >= 3) {
                iRd = numChars - 1;
              }
            }
            break;
        }

      } else {
        digitsChars[iRd] = '\0';
        recvInProgress = false;

        iRd = 0;
        if (strlen(digitsChars) > 0) {
          deg = atoi(digitsChars);
        }
        newData = true;
      }
    }

    else if (rc == startMarker) {
      recvInProgress = true;
    }
  }
}

void onNewData() {
  if (newData == true) {

    Serial.print("Dir: ");
    Serial.println(dir);
    Serial.print("Deg: ");
    Serial.println(deg);

    deg = 0;
    newData = false;
  }
}

void turn(uint8_t dir, int deg) {
  digitalWrite(dirPin, dir);
  digitalWrite(slpPin, HIGH);

  for (int i = 0; i < deg * stepsPerDeg; i++) {
    // These four lines result in 1 step:
    digitalWrite(stepPin, HIGH);
    delayMicroseconds(delay);
    digitalWrite(stepPin, LOW);
    delayMicroseconds(delay);
  }
  digitalWrite(slpPin, LOW);
}