Thanks for replying in my post sir. hmmmm. i dont have any pull down resistor. i will try to it later and post the result sir. but i'm really wondering, how come it recognizes a high value in the input pins of my atmega328 even though i didn't connect any supply? just a connector pin or wire, the other side of it is not connected to any circuit or supply. when i insert the wire into the pins, it sends an sms messages which telling me that it sense a high value.