Published May 16, 2026 © MIT

Basic Arduino Uno PWM Signal Generator

Arduino PWM Signal generator with I2C LCD! There are 3 modes: Manual, Flasher and Breathing. Adjust speed / duty cycle with pot. Smart & com

IntermediateShowcase (no instructions)30 minutes4

Things used in this project

Hardware components

Arduino UNO

Jumper wires (generic)

Rotary potentiometer (generic)

SparkFun Pushbutton switch 12mm

LED (generic)

Breadboard (generic)

Software apps and online services

Arduino IDE

Story

Multi-Mode Arduino PWM Signal Generator & Controller

📝 Project Overview

Test circuits, modulate LEDs, or variable motor speeds need a dependable pulse width modulation (PWM) signal. Function generators sold commercially can be quite large and cost a lot of money. This project presents a low-cost, very portable, multi-mode with I2C 16x2 LCD and dynamic user interface based Arduino-B ased PWM Signal Genera tor.

With one button, a pot, this thing toggles between manual operation and automated signal generation profiles, turning it into a especially useful instrument for any maker's bench.

HOW IT WORKS & THE FEATURES

The system is based on an Arduino Uno/Nano that uses the built in timers to generate a variable PWM signal. The operation has three different modes, you can easily change them by press the hardware interrupt / button:

Manual PWM mode (duty cycle controller) In this you get to manually control the duty cycle from 0% to 100% by turning the pot knob. The actual values are mapped in real time and you can see them on the lcd. It is great for running motor drivers or fading leds.

Flasher Mode (Square Wave/Strobe Generator): In this mode a continuous square wave signal is generated. The frequency or blink delay is up-dated live with the potentiometer to generate perfectly timed pulses.

Breathing Mode (Automated Signal Animation): an automation mode where Arduino automatically increments and decrements the PWM value to simulate a "breath" light effect or a smooth wave signal. The pace of the breathing cycles is regulated by a potentiometer.

The system employs the INPUT_PULLUP scheme for the mode button which eliminates the use for external pull-down resistor and reduces the circuit footprint. In addition, the LCD drawing is made more efficiently with some customized character spacing to resume the screen flickering caused by fast state changes.

📈 Upgrades to Future

While the current firmware directly outputs 5V logic signals from the Arduino pin, the PCB layout is made for an add-on board with an N-Channel MOSFET or a transistor driver circuit. This enables the generator to switch high-current/high-voltage loads such as 12V computer fans, large DC motors, or high-power LED strips (safely!), employing the same code.

Code

PwmSignalGenerator.ino

#include <Wire.h> 
#include <LiquidCrystal_I2C.h>


LiquidCrystal_I2C lcd(0x27, 16, 2); 

const int potPin = A0;      
const int buttonPin = 2;    
const int pwmOut = 9;       

int mod = 0;                
int buttonState;            
int lastButtonState = HIGH; 

void setup() {
  lcd.init();
  lcd.backlight();
  
  pinMode(buttonPin, INPUT_PULLUP); 
  pinMode(pwmOut, OUTPUT);
  

  lcd.setCursor(0, 0);
  lcd.print("MULTIMODE SIGNAL");
  lcd.setCursor(0, 1);
  lcd.print("    GENERATOR   ");
  delay(2500);
  lcd.clear();
}

void loop() {

  int reading = digitalRead(buttonPin);
  if (reading != lastButtonState) {// 
    if (reading == LOW) { 
      mod++;
      if (mod > 2) mod = 0;
      lcd.clear();
      delay(200); 
    }
  }
  lastButtonState = reading;

  int potVal = analogRead(potPin);

  
  if (mod == 0) {
    int pwm = map(potVal, 0, 1023, 0, 255);
    analogWrite(pwmOut, pwm);
    
    lcd.setCursor(0, 0);
    lcd.print("MODE: MANUAL");
    lcd.setCursor(0, 1);
    lcd.print("POWER:%");
    lcd.print(map(pwm, 0, 255, 0, 100));
    lcd.print("    ");
  }


  else if (mod == 1) {
    int hiz = map(potVal, 0, 1023, 20, 500);
    digitalWrite(pwmOut, HIGH);
    delay(hiz);
    digitalWrite(pwmOut, LOW);
    delay(hiz);
    
    lcd.setCursor(0, 0);
    lcd.print("MOD: FLASHER");
    lcd.setCursor(0, 1);
    lcd.print("SPEED: ");
    lcd.print(hiz);
    lcd.print(" ms    ");
  }

else if (mod == 2) {
    static int light = 0;
    static int direction = 1;
    
    analogWrite(pwmOut, light);
    light += direction;
    
    if (light <= 0 || light >= 255) direction *= -1;
    
    int nefesHizi = map(potVal, 0, 1023, 1, 30);
    delay(nefesHizi);
    lcd.setCursor(0, 0);
    lcd.print("MODE: BREATHING ");
    lcd.setCursor(0, 1);
    lcd.print("AUTOMATIC MODE  ");
  }
}

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Basic Arduino Uno PWM Signal Generator

Things used in this project

Hardware components

Software apps and online services

Story

Schematics

pwmsignalgenerator_e5A3R1Kx7X.PNG

Code

PwmSignalGenerator.ino

Credits

Ömüşiki

Comments

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Basic Arduino Uno PWM Signal Generator

Basic Arduino Uno PWM Signal Generator

Things used in this project

Hardware components

Software apps and online services

Story

Schematics

pwmsignalgenerator_e5A3R1Kx7X.PNG

Code

PwmSignalGenerator.ino

Credits

Ömüşiki

Comments

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