Week 2 – Digital Read/Write Circuit & Code

Digital Read a button on pin 2 and digital write an LED on pin 3:

Remember to include a 330 ohm resistor for the LED and a 10k ohm pull down resistor to ground for the button.

int buttonPin = 2;
int ledPin = 3;
int ledState = LOW;
int prevButtonState = LOW;

void setup() {
  // set pin modes
  pinMode(ledPin, OUTPUT);
  pinMode(buttonPin, INPUT);
  // needed in order to start serial communication
  Serial.begin(9600);
}

// PSUEDO CODE:
// check if button is currently pressed
// if button is pressed then check to see if it was pressed during the last frame too
// (we need to remember our button state)
// if button is bressed and previous button is not pressed then flip our LED state

 void loop() {
  // check to see what state our button is in, and store that information
  int currentButtonState = digitalRead(buttonPin);

  // if the button is currently being prssed down, AND during the last frame is wasn't pressed down
  if (currentButtonState == HIGH && prevButtonState == LOW) {
      // flip the LED state
      if (ledState == HIGH){
        ledState = LOW;
      } else if (ledState == LOW){
        ledState = HIGH;
      }
  }
  // if you want to print out the LED state
//  Serial.println(ledState);

  // set our LED to turn on and off according to our variable that we flip above
  digitalWrite(ledPin, ledState);

  //we need to remember the state of our button for the next time through LOOP
  prevButtonState = currentButtonState;
}