int i = 65;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);

}

void loop() {
  // put your main code here, to run repeatedly:
  Serial.write(i);
  Serial.print(" ");
  i++;
  if (i == 91) {
    i = 65;
    Serial.println();
  }
  delay(100);

}