Relay Stutter at Start Up

Hi, using a nano and Sain 4xRelay board and this...

const byte pinOffice = 11;
const byte pinLounge = 12;
const byte pinBedroom = 13;

void setup() 
{ Serial.begin(9600);
  while (!Serial) ; // wait for serial
  delay(200);
  pinMode(pinOffice,OUTPUT);
  digitalWrite(pinOffice,HIGH);
  pinMode(pinLounge,OUTPUT);
  digitalWrite(pinLounge,HIGH);
  pinMode(pinBedroom,OUTPUT);
  digitalWrite(pinBedroom,HIGH);
}

At start up, relay #3 rattles on/off about five times as does the red LED on the Nano.

is this a faulty board or is there something I can do to disable the board until then Nano is ready?

Use a pin other than pin 13. Pin 13 is the one connected to the led, and the bootloader blinks that led to let you know the bootloader is running.

DrAzzy: Use a pin other than pin 13. Pin 13 is the one connected to the led, and the bootloader blinks that led to let you know the bootloader is running.

Arrrggghh, thanks. I have Industrial processing software background and I am used to stuff waiting to be initialized. While I am enjoying playing with the Arduino, some of the stuff is very poorly designed.

The Tx and Rx LEDs blink to let you know stuff is passing through the Serial port (thus the bootloader IS working) on the board, so that should be enough. Even very short programs like Blink, makes them visually-tinkle for a few seconds, so flashing pin/LED-13 is just plain nuts. But then, just ten minutes with the IDE tells me a lot about the behind the scenes stuff. LOL