Mini Fan 4.0

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🎁 Looking for parts?Check out our all-in-one kits below — packed with components, beginner-friendly guides, and tons of fun.

Name	Includes Arduino board	PURCHASE LINK
Elite Explorer Kit	Arduino Uno R4 WiFi	BUY
Universal Maker Sensor Kit	×	BUY
3 in 1 Ultimate Starter Kit	Arduino Uno R3	BUY

Course Introduction

In this lesson, you’ll create a simple control system using a rotary encoder to steer a servo and adjust fan speed. Turning the encoder changes the servo angle, while pressing the button cycles through multiple fan speed levels.

Note

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

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

Wiring

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.

Writing the Code

Note

You can copy this code into Arduino IDE.
Don’t forget to select the board(Arduino UNO R4) and the correct port before clicking the Upload button.

#include <Servo.h>

// Fan motor pins
const int fiPin = 5;   // fixed LOW in this project
const int biPin = 6;   // PWM output to control fan speed

// Servo setup
Servo servo;
const int servoPin = 3;   // servo signal pin

// Rotary encoder pins
const int CLK = 12;    // main signal: detects rotation steps
const int DT  = 11;    // direction signal
const int SW  = 10;    // encoder button (LOW when pressed)

// Variables for encoder reading
int lastCLK = HIGH;              // used to detect edge
unsigned long lastPress = 0;     // debounce timer for SW

// Servo angle control
int angle = 90;                  // starting angle
const int angleMin = 45;         // left limit
const int angleMax = 135;        // right limit
const int angleStep = 2;         // angle change per encoder step

// Fan gear control
int gear = 0;                    // 0~3 speed levels
int fanSpeed = 0;                // actual PWM value

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

  // Encoder pins
  pinMode(CLK, INPUT);
  pinMode(DT, INPUT);
  pinMode(SW, INPUT_PULLUP);     // button is active LOW

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

void loop() {

  // ===============================
  // Read encoder rotation
  // ===============================
  int currentCLK = digitalRead(CLK);

  // Detect the rising edge of CLK (means one "tick")
  if (currentCLK != lastCLK && currentCLK == HIGH) {

    // Compare DT to decide direction
    if (digitalRead(DT) == currentCLK) {
      angle += angleStep;       // clockwise → angle increases
    } else {
      angle -= angleStep;       // counterclockwise → angle decreases
    }

    // Keep the servo angle inside safe limits
    angle = constrain(angle, angleMin, angleMax);

    // Move servo to new angle
    servo.write(angle);
  }

  lastCLK = currentCLK;

  // ===============================
  // Read encoder button (SW)
  // ===============================
  // Button pressed (active LOW)
  if (digitalRead(SW) == LOW) {

    // Simple debounce check
    if (millis() - lastPress > 300) {

      gear++;                   // next speed level

      if (gear > 3) gear = 0;   // wrap around (0→1→2→3→0...)

      lastPress = millis();
    }
  }

  // ===============================
  // Convert gear level to PWM speed
  // ===============================
  if (gear == 0) fanSpeed = 0;      // fan off
  if (gear == 1) fanSpeed = 85;     // low
  if (gear == 2) fanSpeed = 170;    // medium
  if (gear == 3) fanSpeed = 255;    // high

  // ===============================
  // Output speed to fan motor
  // ===============================
  if (fanSpeed > 0) {
    analogWrite(biPin, fanSpeed);   // send PWM speed
    analogWrite(fiPin, 0);          // keep opposite pin LOW
  } else {
    analogWrite(biPin, 0);          // stop fan
    analogWrite(fiPin, 0);
  }
}