Arduino Control Voice - Arduino Code

int estado = 1;
void setup() {
  Serial.begin(9600);
  pinMode(13, OUTPUT);
  pinMode(12, OUTPUT);
  pinMode(11, OUTPUT);
  pinMode(10, OUTPUT);
  pinMode(9, OUTPUT);
  pinMode(8, OUTPUT);
  pinMode(7, OUTPUT);
  pinMode(6, OUTPUT);
}
void loop() {
  if (Serial.available() > 0) {
    estado = Serial.read();
  }
  if (estado == 'a') {
    digitalWrite(13, 1);
  }
  if (estado == 'b') {
    digitalWrite(13, 0);
  }
  if (estado == 'c') {
    digitalWrite(12, 1);
  }
  if (estado == 'd') {
    digitalWrite(12, 0);
  }
  if (estado == 'e') {
    digitalWrite(11, 1);
  }
  if (estado == 'f') {
    digitalWrite(11, 0);
  }
  if (estado == 'g') {
    digitalWrite(10, 1);
  }
  if (estado == 'h') {
    digitalWrite(10, 0);
  }
  if (estado == 'i') {
    digitalWrite(9, 1);
  }
  if (estado == 'j') {
    digitalWrite(9, 0);
  }
  if (estado == 'k') {
    digitalWrite(8, 1);
  }
  if (estado == 'l') {
    digitalWrite(8, 0);
  }
  if (estado == 'm') {
    digitalWrite(7, 1);
  }
  if (estado == 'n') {
    digitalWrite(7, 0);
  }
  if (estado == 'o') {
    digitalWrite(6, 1);
  }
  if (estado == 'p') {
    digitalWrite(6, 0);
  }
  if (estado == 'q') { //all off
    digitalWrite(13, 0);
    digitalWrite(12, 0);
    digitalWrite(11, 0);
    digitalWrite(10, 0);
    digitalWrite(9, 0);
    digitalWrite(8, 0);
    digitalWrite(7, 0);
    digitalWrite(6, 0);
  }
  if (estado == 'r') { // all on
    digitalWrite(13, 1);
    digitalWrite(12, 1);
    digitalWrite(11, 1);
    digitalWrite(10, 1);
    digitalWrite(9, 1);
    digitalWrite(8, 1);
    digitalWrite(7, 1);
    digitalWrite(6, 1);
  }
  if (estado == 's') { // blink
    digitalWrite(13, 1);
    digitalWrite(12, 1);
    digitalWrite(11, 1);
    digitalWrite(10, 1);
    digitalWrite(9, 1);
    digitalWrite(8, 1);
    digitalWrite(7, 1);
    digitalWrite(6, 1);
    delay(500);
    digitalWrite(13, 0);
    digitalWrite(12, 0);
    digitalWrite(11, 0);
    digitalWrite(10, 0);
    digitalWrite(9, 0);
    digitalWrite(8, 0);
    digitalWrite(7, 0);
    digitalWrite(6, 0);
    delay(500);
  }
  if (estado == 't') { //Sequence 1
    digitalWrite(13, 1);
    delay(200);
    digitalWrite(12, 1);
    delay(200);
    digitalWrite(11, 1);
    delay(200);
    digitalWrite(10, 1);
    delay(200);
    digitalWrite(9, 1);
    delay(200);
    digitalWrite(8, 1);
    delay(200);
    digitalWrite(7, 1);
    delay(200);
    digitalWrite(6, 1);
    delay(200);
    digitalWrite(13, 0);
    digitalWrite(12, 0);
    digitalWrite(11, 0);
    digitalWrite(10, 0);
    digitalWrite(9, 0);
    digitalWrite(8, 0);
    digitalWrite(7, 0);
    digitalWrite(6, 0);
    delay(200);
  }
  if (estado == 'u') { //Sequence 2
  }
  if (estado == 'v') { //Sequence 3
    digitalWrite(13, 1);
    delay(200);
    digitalWrite(13, 0);
    digitalWrite(12, 1);
    delay(200);
    digitalWrite(12, 0);
    digitalWrite(11, 1);
    delay(200);
    digitalWrite(11, 0);
    digitalWrite(10, 1);
    delay(200);
    digitalWrite(10, 0);
    digitalWrite(9, 1);
    delay(200);
    digitalWrite(9, 0);
    digitalWrite(8, 1);
    delay(200);
    digitalWrite(8, 0);
    digitalWrite(7, 1);
    delay(200);
    digitalWrite(7, 0);
    digitalWrite(6, 1);
    delay(200);
    digitalWrite(6, 0);
    digitalWrite(7, 1);
    delay(200);
    digitalWrite(7, 0);
    digitalWrite(8, 1);
    delay(200);
    digitalWrite(8, 0);
    digitalWrite(9, 1);
    delay(200);
    digitalWrite(9, 0);
    digitalWrite(10, 1);
    delay(200);
    digitalWrite(10, 0);
    digitalWrite(11, 1);
    delay(200);
    digitalWrite(11, 0);
    digitalWrite(12, 1);
    delay(200);
    digitalWrite(12, 0);
  }
}