Video
Circuit Diagram
Source Code
1int ledState = 0;
2
3void setup() {
4 pinMode(13, INPUT);
5 pinMode(7, OUTPUT);
6}
7
8void loop() {
9 if (digitalRead(13) == 1) {
10 ledState = !ledState;
11 digitalWrite(7, ledState);
12 delay(300);
13 }
14}FAQ
What is debounce, and why is it necessary?▾
When a mechanical button is pressed, it opens and closes multiple times over the course of a few milliseconds (bouncing). The Arduino may interpret this as multiple presses, and the LED remains in a random state. Debounce ignores this bouncing by waiting a short time (e.g., 50 ms) after a state change.
Sometimes the LED doesn't change, or it changes twice—why?▾
Generally, the debounce is either missing or too short. Additionally, you only need to detect the moment the button is "pressed" (previous state: LOW, new state: HIGH); if the state changes in every cycle while the button is held down, the LED will flicker and remain in a random state.
What is the purpose of a state variable?▾
It keeps track of whether the LED is on or off. With each valid press, the variable is inverted (ledStatus = !ledStatus), and the LED is set accordingly.
Can I control different LEDs using multiple buttons?▾
Yes, it's enough to keep a separate pin, a separate previous state, and a separate LED state variable for each button. If you're using a lot of buttons, arrays and millis()-based debounce code will be more organized.