same problem here !

Thank u alot Brother u 've been very helpful to me

will get to u with another big question soon !

i see now . 

i think its my mistake now !!

sry about punctiation.

can u please explain in very short word what is the function of pull up or pull down resistors ! and how to choose their values ! ?




 

still not working guys .. i tell u what exactly happening now !! i upload code to board ... i connect LED with pin 12 and GND ........ then when i just approach my finger to pin 2 without even touching the black insulation  .. THE LED LIGHTS UP !!!!!!!! im going crazy guys !!


else im not connecting any external power source ... just the usb cable !!!!

another question is there any difference between the 3 GND pins on the Arduino Board !

i used exactly the code from examples menu  !!  also i wired the circuit as shown in here http://arduino.cc/en/Tutorial/DigitalReadSerial  with exactly the same resistance !


for the other circuit i used a code just like that !

int button = 2;
int led = 12;

void setup()
{
pinMode(led,OUTPUT);
pinMode(button,INPUT);
}

void loop()

if (digitalRead(button)==HIGH)
{
digitalWrite(led,HIGH);
delay(5000);
}
else
{
digitalWrite(led,LOW);
}

im new to arduino !! i setup the digital read circuit as shown in tutorials ! the TX led is always on even if i didnt push the button !!! i also tried making an LED light if when some push button is pressed ! but also it acts like the button is always pressed !!

in another way when i configure a pin to be an INPUT it always reads HIGH without doing anything to it !!

is my UNO board defective ??