Video
Circuit Diagram
Source Code
1// ─────────────────────────────────────────
2// BlueGrays · bluegrays.com
3// LED Chaser
4// ─────────────────────────────────────────
5// The 6 LEDs light up one after another for 150 ms each, so the light
6// walks along the row. Shows multi-pin control with an array and a for
7// loop.
8//
9// Pins:
10// D2, D3, D4, D5, D6, D7 -> 6 LEDs (in order)
11// Each LED with a 330 ohm resistor
12
13int ledPins[] = {2, 3, 4, 5, 6, 7}; // LED pins in lighting order
14
15void setup() {
16 // Set all LED pins as outputs
17 for(int i = 0; i < 6; i++) {
18 pinMode(ledPins[i], OUTPUT);
19 }
20}
21
22void loop() {
23 // Light each LED in turn for 150 ms
24 for(int i = 0; i < 6; i++) {
25 digitalWrite(ledPins[i], HIGH);
26 delay(150);
27 digitalWrite(ledPins[i], LOW);
28 }
29}
30FAQ
Why is it better to use an array?▾
If you store the pin numbers in an array, you can use a for loop to cycle through all the LEDs in a single line of code. To change the number of LEDs, you just need to update the array; you don't have to write a separate line for each LED.
If 6 LEDs light up at the same time, will the Arduino be damaged?▾
With a 330 Ω resistor, each LED draws approximately 9–10 mA; 6 LEDs total about 60 mA, which is within the Uno’s safe limits. The recommended upper limit for a single pin is 20 mA, and the board’s total I/O current is 200 mA.
How do I reverse the walking direction?▾
Set up the `for` loop in reverse order: `for (int i = 5; i >= 0; i--)`. This way, the light moves in the opposite direction. If you place the two loops one after the other, you’ll get a lightning bolt effect.
One of the LEDs isn't lit—what could be the reason?▾
The LED might be installed upside down, its leg might not be seated properly on the breadboard, or the resistor might be in a different row. You can determine whether the LED is defective or if there’s a connection issue by replacing it with a working LED.