View source for Experiment 5: Controlling DC Motor Using Transistor Driver Circuit

= Experiment 5: Controlling DC Motor Using Transistor Driver Circuit =

== Objective ==
To control a DC motor's speed using PWM output from Arduino through a transistor driver circuit.

== Task ==
# Connect DC motor through to Arduino.  
# Use <code>analogWrite()</code> to vary motor speed.  
# Implement a simple ramp-up or potentiometer-based speed control.

<span style="background-color: #ffcccc; display: inline-block; padding: 5px; border-radius: 5px; font-weight: bold;">
⚠️ Disconnect your Arduino from the computer while making or removing component connections.
</span>

<span style="background-color: #ffff99; display: inline-block; padding: 5px; border-radius: 5px;">
<strong>⚠️ Important Note:</strong><br>
1. Connect only the Arduino Uno (without any component connections) to the computer via USB.<br>
2. Upload the code to the Arduino.<br>
3. Disconnect the Arduino from the computer and remove the USB cable.<br>
4. Make all component connections using patch cords as per the circuit diagram.<br>
5. Then connect the 9V adapter to provide external power supply to the Arduino.
</span>

=== Circuit Diagram (without LCD) ===
[[File:Eecit-kit-05-circuit.png|center|thumb|400px|Circuit Diagram]]

=== Circuit Diagram (with LCD) ===
[[File:Dc-circuit-diagram.png|center|thumb|400px|Circuit Diagram]]

=== Board Connections (without LCD) ===
[[File:Eecit-kit-05-board-connection.png|center|thumb|400px|Board Connections]]

=== Board Connections (with LCD) ===
[[File:Dc-board-diagram.png|center|thumb|400px|Board Connections]]


== Circuit Connections (without LCD) ==
{| class="wikitable" style="text-align:center"
! Component/Pin !! Connect To (Arduino)
|-
| DC Motor (via driver) || Output of Transistor Driver Circuit
|-
| Potentiometer (Vout) || A0
|-
| Motor Input A1 || D5
|-
| Motor Input A2 || D6
|-
| Motor Enable (PWM) || D9
|}

== Code ==
<pre>
// © 2025, Cognifront. Member of The IoT Kits Family.

// Experiment 5: Controlling DC Motor Using Transistor Driver Circuit
// with Serial Monitor output for potentiometer and motor speed

// Define analog input pin connected to the potentiometer
const int Pot = A0;

// Define motor control pins
const int motorA1 = 5;   // Motor driver input A1 (direction control)
const int motorA2 = 6;   // Motor driver input A2 (direction control)
const int enableA = 9;   // Motor driver enable pin (PWM speed control)

void setup() {
  // Start Serial communication for debugging and monitoring
  Serial.begin(9600);

  // Configure potentiometer pin as input (optional for analogRead)
  pinMode(Pot, INPUT);

  // Configure motor control pins as outputs
  pinMode(motorA1, OUTPUT);
  pinMode(motorA2, OUTPUT);
  pinMode(enableA, OUTPUT);
}

void loop() {
  // Read potentiometer value (range 0–1023 from ADC)
  int potVal = analogRead(Pot);           
  
  // Map potentiometer range to motor speed range (0–255 for PWM)
  int speed = map(potVal, 0, 1023, 0, 255);  

  // Set motor direction: A1 HIGH, A2 LOW → rotate in one direction
  digitalWrite(motorA1, HIGH);
  digitalWrite(motorA2, LOW);

  // Control motor speed using PWM signal on enable pin
  analogWrite(enableA, speed);     

  // Display potentiometer value and motor speed on Serial Monitor
  Serial.print("Potentiometer Value: ");
  Serial.print(potVal);
  Serial.print("  |  Motor Speed (PWM): ");
  Serial.println(speed);

  // Small delay for readability in Serial Monitor
  delay(200);          
}
</pre>

== Circuit Connections (with LCD) ==
{| class="wikitable" style="text-align:center"
! Component/Pin !! Connect To (Arduino)
|-
| DC Motor (via driver) || Output of Transistor Driver Circuit
|-
| Potentiometer (Vout) || A0
|-
| Motor Input A1 || D5
|-
| Motor Input A2 || D6
|-
| Motor Enable (PWM) || D9
|-
| LCD VCC || 5V  
|-
| LCD GND || GND  
|-
| LCD SDA || A4  
|-
| LCD SCL || A5
|}

=== Important ===
Before uploading your Arduino code, make sure you have installed the following libraries in the Arduino IDE:
1. Wire.h – For I²C communication between Arduino and peripheral devices.
2. LiquidCrystal_I2C.h – For controlling LCD displays using the I²C interface.

<span style="background-color: #E7DDFF; display: inline-block; padding: 5px; border-radius: 5px; font-weight: bold;">
✅ Install via (ZIP Method):
</span>

<span style="background-color: #E7DDFF; display: inline-block; padding: 5px; border-radius: 5px; font-weight: bold;">
Sketch → Include Library → Add .ZIP Library → Select Downloaded .zip File → Open → Wait for “Library Installed” message
</span>

<span style="background-color: #FFECA1; display: inline-block; padding: 5px; border-radius: 5px; font-weight: bold;">
✅ Verify : 
</span>

<span style="background-color: #FFECA1; display: inline-block; padding: 5px; border-radius: 5px; font-weight: bold;">
Sketch → Include Library → The included library name should be present
</span>

== Code ==
<pre>
// © 2025, Cognifront. Member of The IoT Kits Family.
// Experiment 5: Controlling DC Motor Using Transistor Driver Circuit
// Added: Display potentiometer value and motor speed on 16x2 I2C LCD

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

// I2C address for many modules is 0x27. If nothing appears, try 0x3F.
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Define analog input pin connected to the potentiometer
const int Pot = A0;

// Define motor control pins (using a transistor/H-bridge style driver)
const int motorA1 = 5;   // Motor driver input A1 (direction control)
const int motorA2 = 6;   // Motor driver input A2 (direction control)
const int enableA = 9;   // Motor driver enable pin (PWM speed control)

void setup() {
  // Start Serial communication for debugging and monitoring
  Serial.begin(9600);

  // Configure potentiometer pin as input (optional for analogRead)
  pinMode(Pot, INPUT);

  // Configure motor control pins as outputs
  pinMode(motorA1, OUTPUT);
  pinMode(motorA2, OUTPUT);
  pinMode(enableA, OUTPUT);

  // Initialize LCD
  lcd.init();       // initialize the lcd (some libraries use begin(), init() works for common LiquidCrystal_I2C)
  lcd.backlight();  // turn on backlight
  lcd.clear();

  // Initial display header
  lcd.setCursor(0, 0);
  lcd.print("Pot: ");
  lcd.setCursor(0, 1);
  lcd.print("Speed: ");
}

/*
  🔌 LCD CONNECTIONS (16x2 I2C Display with Arduino UNO)
  ------------------------------------------------------
  LCD Pin     →  Arduino Pin
  ----------------------------
  GND         →  GND
  VCC         →  5V
  SDA         →  A4   (I2C Data line on UNO)
  SCL         →  A5   (I2C Clock line on UNO)
*/

void loop() {
  // Read potentiometer value (range 0–1023 from ADC)
  int potVal = analogRead(Pot);

  // Map potentiometer range to motor speed range (0–255 for PWM)
  int speed = map(potVal, 0, 1023, 0, 255);

  // Set motor direction: A1 HIGH, A2 LOW → rotate in one direction
  digitalWrite(motorA1, HIGH);
  digitalWrite(motorA2, LOW);

  // Control motor speed using PWM signal on enable pin
  analogWrite(enableA, speed);

  // Display potentiometer value and motor speed on Serial Monitor
  Serial.print("Potentiometer Value: ");
  Serial.print(potVal);
  Serial.print("  |  Motor Speed (PWM): ");
  Serial.println(speed);

  // Display on LCD (update only necessary parts; pad with spaces to clear previous digits)
  lcd.setCursor(5, 0);      // after "Pot: "
  lcd.print(potVal);
  lcd.print("   ");         // pad to clear older digits

  lcd.setCursor(7, 1);      // after "Speed: "
  lcd.print(speed);
  lcd.print("   ");         // pad to clear older digits

  delay(200);               // Small delay for readability
}

</pre>

== Observation ==
* As the potentiometer value increases, the PWM duty cycle on pin D9 increases.
* The motor speed changes smoothly in proportion to the potentiometer position.
* Direction remains constant because A1 is HIGH and A2 is LOW.

== Conclusion ==
The DC motor speed can be controlled effectively using PWM output from Arduino and a transistor driver circuit. The potentiometer provides an analog input for real-time speed adjustment, demonstrating a simple method for variable motor speed control.

=== Real Life Example ===
Conveyor Belt Speed Control: Transistor-based motor drivers regulate the speed of conveyor motors used in material handling systems, ensuring smooth movement and controlled transfer of mechanical parts.