Smart Fan1.0

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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 build a temperature-controlled fan using a DHT11 sensor and a DC motor with the Arduino UNO R4.

When the temperature reaches a set threshold, the Arduino turns the fan on at a fixed speed using PWM. As the temperature drops below the threshold, the fan stops automatically.

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	TA6586 - Motor Driver Chip	1
6	Humiture Sensor Module	1
7	Type Miniature DC Motor	1
8	Power Supply	1	BUY

Wiring

Common Connections:

DHT11 Humiture Sensor Module
- DATA: Connect to 2 on the Arduino.
- GND: Connect to breadboard’s negative power bus.
- VCC: Connect to breadboard’s red power bus.
TA6586 - Motor Driver Chip
- BI: Connect to 10 on the Arduino.
- FI: Connect to 9 on the Arduino.
- GND: Connect to breadboard’s negative power bus.
- VCC: Connect to breadboard’s red power bus.
DC Motor
- Connect to B0, F0 on the TA6586 - Motor Driver Chip.

Writing the Code

Note

You can copy this code into Arduino IDE.
Don’t forget to select the board(Arduino UNO R3) and the correct port before clicking the Upload button.

#include <Arduino.h>
#include <DHT.h>

/*
Smart Fan Controller (UNO R4 + DHT11 + TA6586)

Behavior:
    - If T < 27°C  -> Fan OFF
    - If T >= 27°C -> Fan ON at PWM 225

Output:
    - Serial prints temperature and fan state
*/

// ---------- Pin definitions ----------
#define DHT_PIN   2        // DHT11 data pin
#define DHT_TYPE  DHT11

// TA6586 inputs
#define TA_IN1_PWM  9       // Must be PWM-capable pin
#define TA_IN2_DIR  10      // Direction pin (kept LOW for forward)

// ---------- DHT ----------
DHT dht(DHT_PIN, DHT_TYPE);

// ---------- Fan tuning ----------
const float   TEMP_THRESHOLD_C = 27.0f;
const uint8_t FAN_PWM_ON       = 225;   // fixed speed when ON

// ---------- Timing ----------
const unsigned long READ_INTERVAL_MS = 2000; // DHT11 should not be read too fast
unsigned long lastReadMs = 0;

// ---------- Helper: fan control ----------
void fanStop() {
analogWrite(TA_IN1_PWM, 0);
digitalWrite(TA_IN2_DIR, LOW);
}

void fanForward(uint8_t pwm) {
digitalWrite(TA_IN2_DIR, LOW);
analogWrite(TA_IN1_PWM, pwm);
}

// ---------- Setup ----------
void setup() {
pinMode(TA_IN1_PWM, OUTPUT);
pinMode(TA_IN2_DIR, OUTPUT);
fanStop();

Serial.begin(115200);
dht.begin();

Serial.println("Smart Fan Controller Started.");
}

// ---------- Main loop ----------
void loop() {
unsigned long now = millis();
if (now - lastReadMs < READ_INTERVAL_MS) return;
lastReadMs = now;

// Read temperature from DHT11
float t = dht.readTemperature(); // Celsius
if (isnan(t)) {
    fanStop();
    Serial.println("DHT11 read failed! Fan -> OFF");
    return;
}

// Fan control by threshold
if (t >= TEMP_THRESHOLD_C) {
    fanForward(FAN_PWM_ON);
    Serial.print("Temp(C): ");
    Serial.print(t, 1);
    Serial.println(" | Fan: ON (PWM 225)");
} else {
    fanStop();
    Serial.print("Temp(C): ");
    Serial.print(t, 1);
    Serial.println(" | Fan: OFF");
}
}