int Led = 13 ; // define LED Interface int buttonpin = 3; // define the mercury tilt switch sensor interface int val ; // define numeric variables val void setup () { pinMode (Led, OUTPUT) ; // define LED as output interface pinMode (buttonpin, INPUT) ; // define the mercury tilt switch sensor output interface } void loop () { val = digitalRead (buttonpin) ; // read the values assigned to the digital interface 3 val if (val == HIGH) // When the mercury tilt switch sensor detects a signal, LED flashes { digitalWrite (Led, HIGH); } else { digitalWrite (Led, LOW); }