how to change variable when a button connected to pin 2 is pressed

Question

Hi i am writing a code where, i have to switch a variable called toggle from 0 to 1 to 0.... every time the button is pressed (the button is on a 2 pin). I am a little lost as I am new to arduino need some help. Thank you

Answer 1

Go here --> Built-In Examples. Read the examples for Button, Debounce, and Digital Input Pullup. Digital Input Pullup is the best single one of those 3 I think, but read them all.

Those 3 are key.

Also, I wrote a buttonReader (debouncing) library here.

Sounds like you're a beginner, so check out Adafruit's tutorials here.

And lastly, I've compiled links to all my knowledge at the bottom of my article here.

Answer 2

What you need is to detect a transition. That is, either:

• It was closed and is now open.

Or:

• It was open and is now closed.

To do that you need to "remember" the previous state of the switch and detect a change, like this:

const byte switchPin = 8;
byte oldSwitchState = HIGH;  // assume switch open because of pull-up resistor
bool toggle;

void setup ()
  {
  pinMode (switchPin, INPUT_PULLUP);
  }  // end of setup

void loop ()
  {
  // see if switch is open or closed
  byte switchState = digitalRead (switchPin);

  // has it changed since last time?
  if (switchState != oldSwitchState)
    {
    oldSwitchState =  switchState;  // remember for next time 
    toggle = !toggle;   // toggle the variable
    delay (10);         // debounce
    }  // end of state change

  // other code here ...

  }  // end of loop

---

For more information see my post about switches.