Arduino Hands-On Programming and Robotics Course

Here are 6 different LED pattern programs for an Arduino Uno with LEDs connected to Pins 2, 3, 4, 5, and 6.

Circuit Connection

Arduino Pin	LED
D2	LED 1
D3	LED 2
D4	LED 3
D5	LED 4
D6	LED 5

Connection:

Arduino Pin → 220Ω Resistor → LED Anode (+)
LED Cathode (-) → GND

Program 1: All LEDs Blink Together

Output

All LEDs ON → OFF → ON → OFF

int leds[] = {2, 3, 4, 5, 6};

void setup()
{
  for(int i=0; i<5; i++)
  {
    pinMode(leds[i], OUTPUT);
  }
}

void loop()
{
  for(int i=0; i<5; i++)
  {
    digitalWrite(leds[i], HIGH);
  }

  delay(500);

  for(int i=0; i<5; i++)
  {
    digitalWrite(leds[i], LOW);
  }

  delay(500);
}

Program 2: Running Light (Left to Right)

Output

LED1 → LED2 → LED3 → LED4 → LED5

int leds[] = {2, 3, 4, 5, 6};

void setup()
{
  for(int i=0; i<5; i++)
  {
    pinMode(leds[i], OUTPUT);
  }
}

void loop()
{
  for(int i=0; i<5; i++)
  {
    digitalWrite(leds[i], HIGH);
    delay(200);
    digitalWrite(leds[i], LOW);
  }
}

Program 3: Knight Rider Effect

Output

→ → → → →
← ← ← ← ←

int leds[] = {2,3,4,5,6};

void setup()
{
for(int i=0;i<5;i++)
{
pinMode(leds[i],OUTPUT);
}
}

void loop()
{
for(int i=0;i<5;i++)
{
digitalWrite(leds[i],HIGH);
delay(150);
digitalWrite(leds[i],LOW);
}

for(int i=3;i>0;i--)
{
digitalWrite(leds[i],HIGH);
delay(150);
digitalWrite(leds[i],LOW);
}
}

Program 4: Alternate LEDs Blink

Output

LED1 LED3 LED5 ON
LED2 LED4 ON

void setup()
{
  for(int i=2;i<=6;i++)
  {
    pinMode(i,OUTPUT);
  }
}

void loop()
{
  digitalWrite(2,HIGH);
  digitalWrite(4,HIGH);
  digitalWrite(6,HIGH);

  digitalWrite(3,LOW);
  digitalWrite(5,LOW);

  delay(500);

  digitalWrite(2,LOW);
  digitalWrite(4,LOW);
  digitalWrite(6,LOW);

  digitalWrite(3,HIGH);
  digitalWrite(5,HIGH);

  delay(500);
}

Program 5: LED Fill and Empty Pattern

Output

Then LEDs turn OFF one by one.

int leds[] = {2,3,4,5,6};

void setup()
{
for(int i=0;i<5;i++)
{
pinMode(leds[i],OUTPUT);
}
}

void loop()
{
for(int i=0;i<5;i++)
{
digitalWrite(leds[i],HIGH);
delay(300);
}

for(int i=4;i>=0;i--)
{
digitalWrite(leds[i],LOW);
delay(300);
}
}

Program 6: Random LED Blinking

Output

Random LEDs blink continuously.

void setup()
{
  for(int i=2;i<=6;i++)
  {
    pinMode(i,OUTPUT);
  }

  randomSeed(analogRead(A0));
}

void loop()
{
  int led = random(2,7);

  digitalWrite(led,HIGH);
  delay(200);

  digitalWrite(led,LOW);
  delay(200);
}

Bonus Program: Police Light Effect

void setup()
{
for(int i=2;i<=6;i++)
{
pinMode(i,OUTPUT);
}
}

void loop()
{
digitalWrite(2,HIGH);
digitalWrite(3,HIGH);
delay(150);

digitalWrite(2,LOW);
digitalWrite(3,LOW);

digitalWrite(5,HIGH);
digitalWrite(6,HIGH);
delay(150);

digitalWrite(5,LOW);
digitalWrite(6,LOW);
}