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Digital Input: Reading Buttons | NexaLearn IoT Lab | NexaLearn

Digital I/O25 دقيقة

Digital Input: Reading Buttons

How does Arduino know when you pressed the button?

Lesson Content

To make Arduino sense the environment, we use digitalRead(). Buttons act as switches that break or complete a circuit. But if the button is not pressed, does the pin read 0 or 1? The answer: it will read random values because it is 'floating' and is affected by static electricity in the air. To fix this, we use a pull-down resistor to connect it to GND so it reads 0 stably, or we simplify things by using the built-in resistor inside Arduino with INPUT_PULLUP mode.

Components Needed

Arduino Unoزر ضغاط (Push Button)أسلاك

Wiring Notes

Connect one side of the button to GND and the other to pin 2. We'll use INPUT_PULLUP internally.

Code Example

void setup() {
  pinMode(2, INPUT_PULLUP);
  pinMode(13, OUTPUT);
}
void loop() {
  // الزر يعطي LOW عند الضغط لأنه موصل بالـ GND
  if (digitalRead(2) == LOW) {
    digitalWrite(13, HIGH);
  } else {
    digitalWrite(13, LOW);
  }
}

Common Mistakes

Forgetting to use PULLUP, causing the LED to blink randomly just by moving your hand near the button.

Try in Simulator

Open in Wokwi Simulator

Next Lesson

Fake Analog Output (PWM)