PRACTICE: 4 LEDs COUNTING FROM 1 TO 15

PROBLEM INTRODUCTION

In this practical exercise, we will use 4 LEDs to represent numbers from 1 to 15 in binary. This is an excellent way to understand how computers process data and how to control multiple outputs simultaneously.

CIRCUIT CONNECTIONS

Connections:

• LED 1 (LSB): Digital Pin 2
• LED 2: Digital Pin 3
• LED 3: Digital Pin 4
• LED 4 (MSB): Digital Pin 5
• Connect the shorter leg (cathode) of each LED to GND through a 220Ω resistor.

BINARY REPRESENTATION TABLE (1–15)

Decimal Number — LED 4 (8) — LED 3 (4) — LED 2 (2) — LED 1 (1)

1

LED 4: OFF

LED 3: OFF

LED 2: OFF

LED 1: ON

2

LED 4: OFF

LED 3: OFF

LED 2: ON

LED 1: OFF

...

...

15

LED 4: ON

LED 3: ON

LED 2: ON

LED 1: ON

SOURCE CODE

void setup() {

for (int i = 2; i <= 5; i++) {

pinMode(i, OUTPUT);

}

}

void loop() {

for (int count = 1; count <= 15; count++) {

displayBinary(count);

delay(1000);

}

}

void displayBinary(int num) {

for (int i = 0; i < 4; i++) {

// Check each bit of the number

if (bitRead(num, i)) {

digitalWrite(i + 2, HIGH);

} else {

digitalWrite(i + 2, LOW);

}

}

}