Video
Circuit Diagram
Source Code
1// ─────────────────────────────────────────
2// BlueGrays · bluegrays.com
3// LED Control with a Push Button (Push)
4// ─────────────────────────────────────────
5// The LED stays on while the button is held and turns off when it is
6// released (push). Shows reading a button with digitalRead and if-else.
7//
8// Pins:
9// D13 -> Button, other leg to 5V
10// D13 -> 10k resistor to GND (pull-down)
11// D7 -> LED (with a 330 ohm resistor)
12
13void setup() {
14 pinMode(13, INPUT); // Button input (external pull-down)
15 pinMode(7, OUTPUT); // LED output
16}
17
18void loop() {
19 if (digitalRead(13) == HIGH) { // Is the button pressed?
20 digitalWrite(7, HIGH); // Pressed: LED on
21 } else {
22 digitalWrite(7, LOW); // Released: LED off
23 }
24}
25FAQ
What is a 10 kΩ resistor used for?▾
It is a pull-down resistor: it ensures a stable LOW reading by pulling the pin to GND when the button is not pressed. Without this resistor, the pin would be left floating and would read a random HIGH or LOW, causing the LED to flicker on its own.
Can I connect a button without using a resistor?▾
Yes, using `pinMode(pin, INPUT_PULLUP)` enables the Arduino's internal pull-up resistor. In this case, the button is connected between the pin and GND, and the logic is reversed: it reads LOW when pressed and HIGH when released.
Which pins on the button should I use?▾
On 4-pin buttons, the two opposite pins are already connected internally. Place the button over the empty space in the center of the breadboard and use the diagonal pins; this way, you can be sure you’re selecting the correct pins.
What is the difference between "Push" and "On-Off"?▾
In push mode, the LED lights up only while you hold down the button. In on-off (toggle) mode, each press changes the LED's state, and the LED stays on even after you release the button; this requires a state variable.