обнов очка (mega)

char buf[5] = {0, 0, 0, 0, 0};
  static int i = 0;
void setup()
{
  // put your setup code here, to run once:
  Serial.begin(9600);
  Serial3.begin(9600);
}

void loop()
{


  if(Serial.available()>0)
  {
    buf[i] = Serial.read();
    i++;
    Serial.available();
  }

  if(i==3)
  {
    Serial3.write(0xA1);
    Serial3.write(0xF1);
    Serial3.write(buf[0]);
    Serial3.write(buf[1]);
    Serial3.write(buf[2]);
    Serial.println("out serial 3");
    Serial.println(buf[0]);
    Serial.println(buf[1]);
    Serial.println(buf[2]);
    i=0;
  }
  if (Serial3.available()>0) {
    buf[i] = Serial3.read();
    i++;
    Serial3.available();
  }

  if(i==3)
  {
Serial.println("resived serial ");
    Serial.println(buf[0],HEX);
    Serial.println(buf[1],HEX);
    Serial.println(buf[2],HEX);
    i=0;
  }
}