Arduino Car

Hi. My name is Emmanouel and today I am going to share with you, instructions on how to build an Arduino based car using either an available toy car with two main motors (one for steering) and one for the forward/backward motion.

The other classical project is the RC tank. In this case the tank uses both left or right motors for moving and steering. If both right motors move forward and both left motors stay still or move with lower speed then the tank turns right.

In this tutorial we are going to build both a car and a tank.

List of contents

1. Option 1 : Build an Arduino car based on an old RC chassis

1.1 Step 1 Remove the Existing Rc Circuit

1.2 Step 2 Install all components. Schematics as the above picture

1.3 Step 3 Code, Code, More Code…

2. Option 2 : Build an Arduino car based on 4 motors (two left and two right)

2.1 Step 1 Install all components. Schematics as the above picture

2.2 Step 2 Code Code and some more Code!!!

3. More functions (ADVANCED CAR)

Special function: Collision avoidance System

Special Function. Bluetooth dead or alive!!

Code for the advanced car version

4.  Android Application    (link for play store) 

5.  Troubleshooting

Before starting, make sure that you have:

• Arduino uno board
• L298n motor driver
• HC-05  or HC-05 Bluetooth module
• RC Car that that you don’t need any more
• Battery Holder
• 2x 18650 batteries
• Lots of dupont wires

Optional

• 4x leds for lights
• 1x speaker/buzzer for horn sound
• 1x Ultrasonic Distance Sensor – HC-SR04

Step 1 Remove the Existing Rc Circuit

The fun part. Remove everything from the car but the motors and the gears used to move and steer the car. Leave also the cables from the motors in order to be connected to the L298n motor driver

Step 2 Install all components. Schematics as the above picture

Step 3 Code, Code, More Code…

Please unplug the RX and TX pin of the Bluetooth module. Otherwise, you will not be able to upload the code to the Arduino.

#define in1 7 //Right
#define in2 6 //Left
#define en1 3 //turn speed

#define in3 10   //Back
#define in4 11   //Forward
#define en2 5   //Forward speed

#define LED 4          // Front lights  pin
#define LED2 A1        // Back lights pin
const int buzzer = A0; //Buzzer to arduino pin A0 (Horn)

int command; //Int to store app command state.

int pwm_speedA = 255;  //forward speed
int pwm_speedB = 255;  //turn speed

void setup() {

  pinMode(in1, OUTPUT);
  pinMode(in2, OUTPUT);  
  pinMode(en1, OUTPUT);
   
  pinMode(in3, OUTPUT);
  pinMode(in4, OUTPUT);
  pinMode(en2, OUTPUT);
  
  pinMode(LED, OUTPUT);   //Set the Front Lights pin.
  pinMode(LED2, OUTPUT); //Set the Back lights.

  pinMode(buzzer, OUTPUT);  //buzzer to arduino pin A0 (Horn)
  
    Serial.begin(9600);  //Set the baud rate to your Bluetooth module.
}

void loop() {
      
///////////////////////////////////////////////////////////////////////////////////////////
  
  if (Serial.available() > 0) {
    command = Serial.read();
    Stop(); //Initialize with motors stoped.
    switch (command) {
     
///////////////////////////////////// Turn on/off Front lights
     case 'W':
        digitalWrite(LED, HIGH);
         break;
      
     case 'w':
        digitalWrite(LED, LOW);
         break;

//////////////////////////////////////   Turn on/off Back lights
      case 'U':
        digitalWrite(LED2, HIGH);
        break;
      
      case 'u':
        digitalWrite(LED2, LOW);
        break;
/////////////////////////////////////// Toggle on/off Horn
      case 'V':
        tone(buzzer, 2500); // Send 1KHz sound signal...
        break;
      
      case 'v':
          noTone(buzzer);// Stop sound...
        break;
////////////////////////////////////////
      
      case 'F':
        forward();
        break;
      case 'B':
        back();
        break;
      case 'L':
        left();
        break;
      case 'R':
        right();
        break;
      case 'G':
        forwardleft();
        break;
      case 'I':
        forwardright();
        break;
      case 'H':
        backleft();
        break;
      case 'J':
        backright();
        break;
      case '0':
        pwm_speedA = 100;
        break;
      case '1':
        pwm_speedA = 140;
        break;
      case '2':
        pwm_speedA = 153;
        break;
      case '3':
        pwm_speedA = 165;
        break;
      case '4':
        pwm_speedA = 178;
        break;
      case '5':
        pwm_speedA = 191;
         break;
      case '6':
        pwm_speedA = 204;
        break;
      case '7':
        pwm_speedA=216;
        
        break;
      case '8':
        pwm_speedA = 229;
        break;
      case '9':
        pwm_speedA = 242;
        break;
      case 'q':
        pwm_speedA = 255;      
        break;
    }
  
        
  }
}

void forward() {
  digitalWrite(in4, HIGH);  
  analogWrite(en2,pwm_speedA); 
}

void back() {
  digitalWrite(in3, HIGH);
  analogWrite(en2,pwm_speedA);
}

void left() {
  digitalWrite(in2, HIGH);
  analogWrite(en1,pwm_speedB);
}

void right() {
  digitalWrite(in1, HIGH);
analogWrite(en1,pwm_speedB);
  }
void forwardleft() {
  digitalWrite(in4, HIGH);  
  analogWrite(en2,pwm_speedA);
  
  digitalWrite(in2, HIGH);
  analogWrite(en1,pwm_speedB);
  
}
void forwardright() {
  digitalWrite(in4, HIGH);  
  analogWrite(en2,pwm_speedA);
  
  
  digitalWrite(in1, HIGH);
analogWrite(en1,pwm_speedB);
}
void backright() {
  digitalWrite(in3, HIGH);
  analogWrite(en2,pwm_speedA);
    
    digitalWrite(in1, HIGH);
analogWrite(en1,pwm_speedB);
}
void backleft() {
  digitalWrite(in3, HIGH);
  analogWrite(en2,pwm_speedA);
  
    digitalWrite(in2, HIGH);
  analogWrite(en1,pwm_speedB);
}

void Stop() {
  analogWrite(in1, 0);
  analogWrite(in2, 0);
  analogWrite(in3, 0);
  analogWrite(in4, 0);
}

Before starting, make sure that you have:

• Arduino uno board
• L298n motor driver
• HC-05  or HC-05 Bluetooth module
• Car with 4 motors as the above picture
• Battery Holder
• 2x 18650 batteries
• Lots of dupont wires

Optional

• 4x leds for lights
• 1x speaker/buzzer for horn sound
• 1x Ultrasonic Distance Sensor – HC-SR04

Step 2 Install all components. Schematics as the above picture

Step 3 Code Code and some more Code!!!

#define in1 7 //Right
#define in2 6 //Right
#define en1 3 //right speed

#define in3 10   //Left
#define in4 11   //Left
#define en2 5   //Left speed

#define LED 4          // Front lights  pin
#define LED2 A1        // Back lights pin
const int buzzer = A0; //Buzzer to arduino pin A0 (Horn)


int command; //Int to store app command state.

int pwm_speedA = 255;  //forward speed
int pwm_speedB = 48;  //turn speed

void setup() {

  pinMode(in1, OUTPUT);
  pinMode(in2, OUTPUT);  
  pinMode(en1, OUTPUT);
   
  pinMode(in3, OUTPUT);
  pinMode(in4, OUTPUT);
  pinMode(en2, OUTPUT);
  
  pinMode(LED, OUTPUT);   //Set the Front Lights pin.
  pinMode(LED2, OUTPUT); //Set the Back lights.

  pinMode(buzzer, OUTPUT);  //buzzer to arduino pin A0 (Horn)
  
  Serial.begin(9600);  //Set the baud rate to your Bluetooth module.
}

void loop() {
  
  if (Serial.available() > 0) {
    command = Serial.read();
    Stop(); //Initialize with motors stoped.
    switch (command) {
     
///////////////////////////////////// Turn on/off Front lights
     case 'W':
        digitalWrite(LED, HIGH);
         break;
      
     case 'w':
        digitalWrite(LED, LOW);
         break;
//////////////////////////////////////   Turn on/off Back lights
      case 'U':
        digitalWrite(LED2, HIGH);
        break;
      
      case 'u':
        digitalWrite(LED2, LOW);
        break;
/////////////////////////////////////// Toggle on/off Horn
      case 'V':
        tone(buzzer, 2500); // Send 1KHz sound signal...
        break;
      
      case 'v':
          noTone(buzzer);// Stop sound...
        break;
////////////////////////////////////////
      
      case 'F':
        forward();
        break;
      case 'B':
        back();
        break;
      case 'L':
        left();
        break;
      case 'R':
        right();
        break;
      case 'G':
        forwardleft();
        break;
      case 'I':
        forwardright();
        break;
      case 'H':
        backleft();
        break;
      case 'J':
        backright();
        break;
      case '0':
        pwm_speedA = 100;
        break;
      case '1':
        pwm_speedA = 140;
        break;
      case '2':
        pwm_speedA = 153;
        break;
      case '3':
        pwm_speedA = 165;
        break;
      case '4':
        pwm_speedA = 178;
        break;
      case '5':
        pwm_speedA = 191;
         break;
      case '6':
        pwm_speedA = 204;
        break;
      case '7':
        pwm_speedA=216;
        
        break;
      case '8':
        pwm_speedA = 229;
        break;
      case '9':
        pwm_speedA = 242;
        break;
      case 'q':
        pwm_speedA = 255;      
        break;
    }
    
  }
}

void forward() {
  digitalWrite(in3, HIGH);  
  analogWrite(en2,pwm_speedA); 
  
  digitalWrite(in2, HIGH);  
  analogWrite(en1,pwm_speedA);

}

void back() {
  digitalWrite(in1, HIGH);  
  analogWrite(en1,pwm_speedA); 
  
  digitalWrite(in4, HIGH);  
  analogWrite(en2,pwm_speedA);
}

void left() {
  digitalWrite(in3, HIGH);
  analogWrite(en2,pwm_speedA);
  
  digitalWrite(in1, HIGH);
  analogWrite(en1,pwm_speedA);
}

void right() {
  digitalWrite(in2, HIGH);
analogWrite(en1,pwm_speedA);

digitalWrite(in4, HIGH);
  analogWrite(en2,pwm_speedA);
  }
void forwardleft() {
  digitalWrite(in3, HIGH);  
  analogWrite(en2,pwm_speedA); 
  
  digitalWrite(in2, HIGH);  
  analogWrite(en1,pwm_speedB);
  
}
void forwardright() {
  digitalWrite(in3, HIGH);  
  analogWrite(en2,pwm_speedB); 
  
  digitalWrite(in2, HIGH);  
  analogWrite(en1,pwm_speedA);
}
void backright() {
  digitalWrite(in1, HIGH);
  analogWrite(en1,pwm_speedA);
    
    digitalWrite(in4, HIGH);
analogWrite(en2,pwm_speedB);
}
void backleft() {
  digitalWrite(in1, HIGH);
  analogWrite(en1,pwm_speedB);
      
  digitalWrite(in4, HIGH);
analogWrite(en2,pwm_speedA);
}

void Stop() {
  analogWrite(in1, 0);
  analogWrite(in2, 0);
  analogWrite(in3, 0);
  analogWrite(in4, 0);
}

Special function: Collision avoidance System

You can install in front of the car an HC-SR04 ultrasonic sensor. In this way the sensor measures obstacles that are in the way. When the distance measured, is below 10 cm (you can adjust it) and the special key D is sent from the app (Menu -> Collision button is enabled) the car is going backwards for half a second and then it stops

SR04 pins

Echo Pin to Arduino Pin 9

Trig Pin to Arduino Pin 8The Schematics and the code for the Arduino in this case is

Special Function. Bluetooth dead or alive!!

Imagine you move forward your car and suddenly Bluetooth is disconnected. Your car will continue to move forward.

The solution. The state pin! Connect the state pin of your Bluetooth module to the Arduino pin 12.

Load the full version code below. That’s it . The code reads pin 12. If the Bluetooth is connected pin 12 has voltage if not the Arduino stops all motors

So to enable this function delete // comment from the above code within the code provided

if (digitalRead(BTpin)==LOW){
Stop();
}

If your is not responding or just moves for a tenth of second please make sure that your Bluetooth module  supports this function. I own some Bluetooth modules that it didn’t work

Code for the advanced car

Please unplug the RX and TX pin of the Bluetooth module. Otherwise, you will not be able to upload the code to the Arduino.

The application is available on Google Play (link)

This application was created by me using appinventor. Maybe, in the future I will post a tutorial on how the app was made.

How the app works.

Simple. It just sends when a button is pressed a character over the serial port.

Also there are some special features

• Remote control Interface
• Vibration
• Sounds when buttons are pressed
• Front lights and back lights buttons
• Three Function buttons for custom use
• Panel showing the command send to the Bluetooth
• Link to web page with detailed instructions
• Arduino code provided
• Speed control

The characters send to the Bluetooth are

• Forward (F)
• Back (B)
• Right (R)
• Left (L)
• Forward Left (G)
• Forward Right (I)
• Backward Left (H)
• Backward Right (J)
• Front lights on (W) off (w)
• Back Lights on (U) off (u)
• Horn on (V) off (v)
• Special button F1 on (K) off (k)
• Special button F2 on (P) off (p)
• Special button F3 on (N) off (n)
• Collision Avoidance system Enable (M) Disable (m)

 1.  If the car is not going on the right direction.

If this happens and your car is not going in the right direction then you don’t have to modify any code. You have to just change the motor driver wires in pairs.

For instance swap in1 with in2 or in3 with in4 pins

2.  Cannot upload the code to the Arduino

You must know that when you are uploading the code to the Arduino. You must unplug the RX and TX pin of the Bluetooth module. Otherwise, you will not be able to upload the code to the Arduino.

3.  The car in not responding the right way or often Bluetooth disconnections.

There is not enough power supply. Please make sure that both 18650 batteries are full charged