Introduction: The NOT Gate With Arduino

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About: An Electrical Engineering Teacher in Athens Greece. Most of these small projects here, are constructed for enhancing the learning of the use of Arduino as well as basic electricity and electronics for students… 
/*Arduino_NOT_Logic_Gate. A simple circuit to view the NOT gate. 
And exploring simple forms of code. 
Change the code to buttonStatus == HIGH and see what happens.*/ 
int buttonPin = 2;  
int ledPin = 8;  
int buttonStatus = 0; 
void setup() {
 pinMode(ledPin, OUTPUT); 
 pinMode(buttonPin, INPUT);
} 

void loop(){     
buttonStatus = digitalRead(buttonPin); 
 if (buttonStatus == LOW) {  // check if the button state is LOW if yes then turn the LED on
 digitalWrite(ledPin, HIGH); 
 }  
else { digitalWrite(ledPin, LOW); // else if the button state is HIGH turn the LED off
 }
}

Step 1: Step 2 Variation

/*Arduino_NOT_Logic_Gate. Another variation in the code would be this*/
int buttonPin = 2; 
int ledPin = 8; 
int buttonStatus = 0; 
void setup() {
pinMode(ledPin, OUTPUT); 
pinMode(buttonPin, INPUT); 
} 
void loop(){ 
buttonStatus = digitalRead(buttonPin); 
if (buttonStatus != HIGH) // if the button is not (!=) HIGH (hence LOW) turn on the LED
{digitalWrite(ledPin, HIGH);   } 

else { digitalWrite(ledPin, LOW); } 
}

Step 2: