Arduino Project

Arduino Fan Speed Control Project with DC Motor V5

Course Introduction

In this lesson, you’ll build a smart fan controller using a rotary encoder, a servo, an LCD, and PWM motor control. Turning the encoder adjusts the servo angle, pressing the button switches between fan speed levels, and the LCD displays real-time angle and gear information.

Note

If this is your first time working with an Arduino project, we recommend downloading and reviewing the basic materials first.

1.1 Install Arduino IDE(Important)
1.2 Introduction of Arduino IDE

Required Components

In this project, we need the following components:

SN	COMPONENT INTRODUCTION	QUANTITY	PURCHASE LINK
1	Arduino UNO R4 Minima/Arduino UNO R4 WIFI	1	BUY
2	USB Cable	1	×
3	Breadboard	1	BUY
4	Wires	Several	BUY
5	DC Motor	1	BUY
6	TA6586 - Motor Driver Chip	1	×
7	Rotary Encoder Module	1	BUY
8	Digital Servo Motor	1	BUY
9	I2C LCD 1602	1	BUY

Wiring

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Common Connections:

TA6586 - Motor Driver Chip
BI: Connect to 6 on the Arduino.
FI: Connect to 5 on the Arduino.
GND: Connect to breadboard’s negative power bus.
VCC: Connect to breadboard’s red power bus.

DC Motor
GND: Connect to TA6586 B0.
VCC: Connect to TA6586 F0.

Rotary Encoder Module
CLK: Connect to 12 on the Arduino.
DT: Connect to 11 on the Arduino.
SW: Connect to 10 on the Arduino.
GND: Connect to breadboard’s negative power bus.
VCC: Connect to breadboard’s red power bus.

Digital Servo Motor
Connect to breadboard’s positive power bus.
Connect to breadboard’s negative power bus.
Connect to 3 on the Arduino.

I2C LCD 1602
SDA: Connect to A4 on the Arduino.
SCL: Connect to A5 on the Arduino.
GND: Connect to breadboard’s negative power bus.
VCC: Connect to breadboard’s red power bus.

Writing the Code

Note
You can copy this code into Arduino IDE.
To install the library, use the Arduino Library Manager and search for LiquidCrystal I2C and install it.
Don’t forget to select the board(Arduino UNO R4 WIFI) and the correct port before clicking the Upload button.

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

// LCD using I2C (address may be 0x27 or 0x3F)
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Fan output pins
const int fiPin = 5;
const int biPin = 6;

// Servo
Servo servo;
const int servoPin = 3;

// Rotary encoder pins
const int CLK = 12;    // rotation signal A
const int DT  = 11;    // rotation signal B
const int SW  = 10;    // push button (LOW when pressed)

// Encoder state tracking
int lastCLK = HIGH;
unsigned long lastPress = 0;

// Servo angle settings
int angle = 90;
const int angleMin = 45;
const int angleMax = 135;
const int angleStep = 5;   // rotate encoder = change 5 degrees

// Fan gear levels (0 = off)
int gear = 0;
int fanSpeed = 0;

// LCD update tracking
int lastAngle = -1;
int lastGear  = -1;

void setup() {
  // Motor pins
  pinMode(fiPin, OUTPUT);
  pinMode(biPin, OUTPUT);

  // Encoder pins with pull-ups for stable signals
  pinMode(CLK, INPUT_PULLUP);
  pinMode(DT,  INPUT_PULLUP);
  pinMode(SW,  INPUT_PULLUP);

  // Servo setup
  servo.attach(servoPin);
  servo.write(angle);

  // LCD setup
  lcd.init();
  lcd.backlight();
  lcd.clear();
}

void loop() {

  // ----------------------------------------------------
  // Read rotary encoder rotation
  // Only allowed when fan gear > 0 (fan ON)
  // Falling edge of CLK gives stable step detection
  // ----------------------------------------------------
  int currentCLK = digitalRead(CLK);

  if (currentCLK == LOW && lastCLK == HIGH) {

    if (gear > 0) {   // servo locked when gear = 0 (fan OFF)

      // Determine rotation direction
      if (digitalRead(DT) == HIGH) {
        angle += angleStep;    // clockwise
      } else {
        angle -= angleStep;    // counterclockwise
      }

      // Keep angle within safe limits
      angle = constrain(angle, angleMin, angleMax);
      servo.write(angle);
    }
  }
  lastCLK = currentCLK;

  // ----------------------------------------------------
  // Change fan gear (0 → 3) when encoder button pressed
  // ----------------------------------------------------
  if (digitalRead(SW) == LOW) {
    if (millis() - lastPress > 300) {   // debounce

      gear++;
      if (gear > 3) gear = 0;           // loop back

      lastPress = millis();
    }
  }

  // ----------------------------------------------------
  // Convert gear level to fan PWM value
  // ----------------------------------------------------
  if (gear == 0) fanSpeed = 0;
  if (gear == 1) fanSpeed = 85;
  if (gear == 2) fanSpeed = 170;
  if (gear == 3) fanSpeed = 255;

  analogWrite(biPin, fanSpeed);
  analogWrite(fiPin, 0); // fixed LOW direction

  // ----------------------------------------------------
  // Update LCD only when values change
  // Reduces I2C traffic → prevents encoder lag
  // ----------------------------------------------------
  if (angle != lastAngle || gear != lastGear) {

    lcd.setCursor(0, 0);
    lcd.print("Angle:");
    lcd.print(angle);
    lcd.print("   ");

    lcd.setCursor(0, 1);
    lcd.print("Gear:");
    lcd.print(gear);
    lcd.print(" PWM:");
    lcd.print(fanSpeed);
    lcd.print("   ");

    lastAngle = angle;
    lastGear  = gear;
  }
}

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Arduino Project

Arduino Fan Speed Control Project with DC Motor V5

Course Introduction

Required Components

Wiring

Common Connections:

Writing the Code

Arduino Project

Arduino Fan Speed Control Project with DC Motor V5

Course Introduction

Required Components

Wiring

Common Connections:

Writing the Code

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