Arduino and Multiplexer

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Hello In this article we will see how you can increase the output of the Arduino UNO board by using the 74HC4051 Multiplixer , we wil controll 8 LEDS! This Project is simulated using Proteus 8!

Schematic:

Code for LED Brightness Controller:

// File: led_brightness_controller_with_inh.ino

// Define multiplexer control pins
#define A 2
#define B 3
#define C 4

// Define PWM output pin
#define PWM_PIN 9

// Define INH (inhibit) pin
#define INH 5

// Brightness levels for each LED (0 to 255)
int brightnessLevels[8] = {50, 100, 150, 200, 255, 180, 90, 60};

void setup() {
  // Set control pins as output
  pinMode(A, OUTPUT);
  pinMode(B, OUTPUT);
  pinMode(C, OUTPUT);

  // Set INH pin as output and disable inhibit
  pinMode(INH, OUTPUT);
  digitalWrite(INH, LOW); // Enable multiplexer

  // Set PWM pin as output
  pinMode(PWM_PIN, OUTPUT);
}

void loop() {
  for (int i = 0; i < 8; i++) {
    // Set multiplexer channel
    selectChannel(i);

    // Write the corresponding brightness level to the PWM pin
    analogWrite(PWM_PIN, brightnessLevels[i]);

    // Hold for a short time to make the brightness visible
    delay(100);
  }
}

// Function to select the active multiplexer channel
void selectChannel(int channel) {
  digitalWrite(A, channel & 0x01); // Least significant bit
  digitalWrite(B, (channel >> 1) & 0x01);
  digitalWrite(C, (channel >> 2) & 0x01);
}

Code: Brightness Equalizer

#define A 2
#define B 3
#define C 4
#define PWM_PIN 9
#define INH 5
#define POT_PIN A0

void setup() {
  pinMode(A, OUTPUT);
  pinMode(B, OUTPUT);
  pinMode(C, OUTPUT);
  pinMode(INH, OUTPUT);
  digitalWrite(INH, LOW); // Enable multiplexer
  pinMode(PWM_PIN, OUTPUT);
}

void loop() {
  int potValue = analogRead(POT_PIN);         // Read potentiometer value
  int brightness = map(potValue, 0, 1023, 0, 255); // Map to PWM range

  for (int i = 0; i < 8; i++) {
    selectChannel(i);
    analogWrite(PWM_PIN, brightness);
    delay(100);
  }
}

void selectChannel(int channel) {
  digitalWrite(A, channel & 0x01);
  digitalWrite(B, (channel >> 1) & 0x01);
  digitalWrite(C, (channel >> 2) & 0x01);
}

Code: SOS Signal

#define A 2
#define B 3
#define C 4
#define PWM_PIN 9
#define INH 5

void setup() {
pinMode(A, OUTPUT);
pinMode(B, OUTPUT);
pinMode(C, OUTPUT);
pinMode(INH, OUTPUT);
digitalWrite(INH, LOW); // Enable multiplexer
pinMode(PWM_PIN, OUTPUT);
}

void loop() {
for (int i = 0; i < 8; i++) {
sendSOS(i);
delay(2000); // Pause between SOS signals
}
}

void sendSOS(int channel) {
selectChannel(channel);

// Dot-Dot-Dot
for (int i = 0; i < 3; i++) {
analogWrite(PWM_PIN, 255);
delay(200); // Short flash
analogWrite(PWM_PIN, 0);
delay(200);
}

// Dash-Dash-Dash
for (int i = 0; i < 3; i++) {
analogWrite(PWM_PIN, 255);
delay(600); // Long flash
analogWrite(PWM_PIN, 0);
delay(200);
}

// Dot-Dot-Dot
for (int i = 0; i < 3; i++) {
analogWrite(PWM_PIN, 255);
delay(200); // Short flash
analogWrite(PWM_PIN, 0);
delay(200);
}
}

void selectChannel(int channel) {
digitalWrite(A, channel & 0x01);
digitalWrite(B, (channel >> 1) & 0x01);
digitalWrite(C, (channel >> 2) & 0x01);
}

Code: LED Chaser

// File: led_chaser.ino

#define A 2
#define B 3
#define C 4
#define PWM_PIN 9
#define INH 5

void setup() {
  pinMode(A, OUTPUT);
  pinMode(B, OUTPUT);
  pinMode(C, OUTPUT);
  pinMode(INH, OUTPUT);
  digitalWrite(INH, LOW); // Enable multiplexer
  pinMode(PWM_PIN, OUTPUT);
}

void loop() {
  for (int i = 0; i < 8; i++) {
    // Gradually increase brightness
    for (int brightness = 0; brightness <= 255; brightness += 5) {
      selectChannel(i);
      analogWrite(PWM_PIN, brightness);
      delay(10);
    }

    // Gradually decrease brightness
    for (int brightness = 255; brightness >= 0; brightness -= 5) {
      selectChannel(i);
      analogWrite(PWM_PIN, brightness);
      delay(10);
    }
  }
}

void selectChannel(int channel) {
  digitalWrite(A, channel & 0x01);
  digitalWrite(B, (channel >> 1) & 0x01);
  digitalWrite(C, (channel >> 2) & 0x01);
}

Schematic of this project:






Code: Reaction Game
#include <Arduino.h>

#define A 2
#define B 3
#define C 4
#define PWM_PIN 9
#define INH 5
#define BUTTON_PIN 6

void setup() {
  pinMode(A, OUTPUT);
  pinMode(B, OUTPUT);
  pinMode(C, OUTPUT);
  pinMode(INH, OUTPUT);
  digitalWrite(INH, LOW); // Enable multiplexer
  pinMode(PWM_PIN, OUTPUT);
  pinMode(BUTTON_PIN, INPUT_PULLUP); // Button with pull-up resistor
  Serial.begin(9600);
}

void loop() {
  int randomLED = random(0, 8); // Pick a random LED
  selectChannel(randomLED);
  analogWrite(PWM_PIN, 255); // Turn on LED

  unsigned long startTime = millis();
  while (digitalRead(BUTTON_PIN) == HIGH); // Wait for button press

  unsigned long reactionTime = millis() - startTime;
  Serial.print("Reaction Time: ");
  Serial.println(reactionTime);

  analogWrite(PWM_PIN, 0); // Turn off LED
  delay(1000); // Wait before next round
}

void selectChannel(int channel) {
  digitalWrite(A, channel & 0x01);
  digitalWrite(B, (channel >> 1) & 0x01);
  digitalWrite(C, (channel >> 2) & 0x01);
}




Find the full Project here: 
https://drive.google.com/file/d/1LNoW0uWOdzJTwrX-_cId1JDb2VolpdRl/view?usp=drive_link