A 2WD robot car controlled by an ESP32 over Wi-Fi using a WebSocket-based web interface.

This project is built as a hands-on embedded systems learning project using C++, ESP32, FreeRTOS, Wi-Fi, WebSocket, GPIO, and the TB6612FNG motor driver.

Overview

The car uses an ESP32 as the main controller.

The ESP32 creates its own Wi-Fi network and hosts a web page. A phone or computer connects to this network and opens the control interface.

The control commands are sent from the browser to the ESP32 using WebSocket.

The ESP32 then sends motor-control signals to the TB6612FNG motor driver.

                  PHONE / PC
                       |
                       | Wi-Fi
                       |
                       v
                +--------------+
                |    ESP32     |
                |              |
                | WebSocket    |
                +------+-------+
                       |
                  GPIO signals
                       |
                       v
                +--------------+
                |  TB6612FNG   |
                | Motor Driver |
                +------+-------+
                       |
                +------+------+
                |             |
                v             v
           LEFT MOTOR    RIGHT MOTOR

Current Status

The current version is working.

Implemented:

2WD robot chassis
Two DC geared motors
TB6612FNG motor driver
ESP32 NodeMCU-32S
ESP32 Wi-Fi Access Point
HTTP web server
WebSocket communication
Browser-based control interface
Forward movement
Backward movement
Left turn
Right turn
Stop
WebSocket disconnect safety stop
FreeRTOS task separation
Core 0 web task
Core 1 car-control task
FreeRTOS command queue

The HC-SR04 ultrasonic sensor is not used in the current version.

Hardware

Components

Component	Quantity	Purpose	Approx. Cost
ESP32 NodeMCU-32S	1	Main controller	₹399
2WD Robot Car Kit	1	Chassis, motors, wheels, battery holder	₹279
TB6612FNG Dual DC Motor Driver	1	Motor control	₹133
AA Batteries	4	Motor power	Existing
Jumper Wires	As required	Connections	Existing
USB Cable	1	ESP32 power/programming	Existing

Approximate cost of the main purchased components:

ESP32          ₹399
2WD Kit        ₹279
TB6612FNG      ₹133
--------------------
Total          ₹811

Prices may change.

Purchase Links

Hardware Architecture

The ESP32 does not directly drive the motors.

The ESP32 GPIO pins provide low-power control signals to the TB6612FNG.

The TB6612FNG handles the motor-side electrical power.

ESP32 GPIO
    |
    | Direction / Enable
    v
TB6612FNG
    |
    | Motor power
    v
DC Motors

The TB6612FNG contains two motor-control channels:

              TB6612FNG

        +-------------------+
        |                   |
        |    Channel A      |---- Left Motor
        |                   |
        |    Channel B      |---- Right Motor
        |                   |
        +-------------------+

Wiring

ESP32 to TB6612FNG

ESP32	TB6612FNG	Purpose
GPIO 25	PWMA	Left motor speed/enable
GPIO 26	AIN1	Left motor direction
GPIO 27	AIN2	Left motor direction
GPIO 14	PWMB	Right motor speed/enable
GPIO 32	BIN1	Right motor direction
GPIO 33	BIN2	Right motor direction
GPIO 13	STBY	Motor driver enable
3.3V	VCC	Logic supply
GND	GND	Common ground

Wiring diagram

ESP32                         TB6612FNG
------------------------------------------------

GPIO 25  ------------------> PWMA
GPIO 26  ------------------> AIN1
GPIO 27  ------------------> AIN2

GPIO 14  ------------------> PWMB
GPIO 32  ------------------> BIN1
GPIO 33  ------------------> BIN2

GPIO 13  ------------------> STBY

3.3V     ------------------> VCC
GND      ------------------> GND

Motor Connections

The left motor is connected to Channel A.

TB6612FNG

AO1 -------- Left Motor
AO2 -------- Left Motor

The right motor is connected to Channel B.

TB6612FNG

BO1 -------- Right Motor
BO2 -------- Right Motor

A DC motor changes its rotation direction when the polarity across its terminals is reversed.

During testing, the right motor rotated in the opposite direction.

The two right-motor wires were swapped to correct the direction.

Power

During development, the ESP32 is powered through USB from the laptop.

The motors receive power from the battery holder through the TB6612FNG.

                 LAPTOP
                    |
                   USB
                    |
                    v
                +-------+
                | ESP32 |
                +---+---+
                    |
                 GPIOs
                    |
                    v
              +-----------+
              | TB6612FNG |
              +-----+-----+
                    |
              +-----+-----+
              |           |
              v           v
         LEFT MOTOR   RIGHT MOTOR

The motor battery is connected to the motor driver's motor-voltage input.

Battery +
    |
  Switch
    |
    v
TB6612 VM

Battery -
    |
    v
TB6612 GND

The ESP32 and TB6612FNG share a common ground.

ESP32 GND
    |
    +---------- TB6612FNG GND
                     |
                     +---------- Battery -

Important

The ESP32 is currently powered through USB during development.

The motor battery supply is separate.

Do not connect a battery directly to the ESP32 5V pin unless its voltage is known to be within the board's acceptable input range.

Software

Development Environment

Operating System : Windows 10
IDE              : VS Code
Build System     : PlatformIO
Framework        : Arduino
Language         : C++
Board            : NodeMCU-32S

Project Structure

The code is separated into three main parts.

ESP32_TB6612FNG_Web_controlled_Car/
│
├── platformio.ini
├── README.md
│
└── src/
    │
    ├── main.cpp
    │
    ├── webpage.cpp
    ├── webpage.h
    │
    ├── car.cpp
    └── car.h

`main.cpp`

Responsible for:

Starting the application
Creating the FreeRTOS command queue
Creating the web task
Creating the car task
Assigning tasks to CPU cores

`webpage.cpp`

Responsible for:

Wi-Fi Access Point
HTTP server
WebSocket server
HTML
CSS
JavaScript
Receiving commands from the browser
Sending commands to the FreeRTOS queue

`car.cpp`

Responsible for:

TB6612FNG initialization
Motor GPIO configuration
Forward movement
Backward movement
Left turn
Right turn
Stop

Wi-Fi

The ESP32 runs in Access Point mode.

It creates its own Wi-Fi network.

SSID:     ESP32-CAR
Password: esp32car
IP:       192.168.4.1

The phone connects directly to the ESP32.

Phone
  |
  | Wi-Fi
  v
ESP32-CAR

Internet access is not required.

Web Interface

The ESP32 hosts a simple control webpage.

The interface is arranged with movement controls on the sides and the connection status and STOP button in the center.

+-------------------------------------------+
|                 ESP32 CAR                 |
|                                           |
|                 Connected                 |
|                                           |
|     +-----+                 +-----+       |
|     |  ▲  |                 |  ◀  |       |
|     +-----+                 +-----+       |
|                                           |
|     +-----+       +------+  +-----+       |
|     |  ▼  |       | STOP |  |  ▶  |       |
|     +-----+       +------+  +-----+       |
|                                           |
+-------------------------------------------+

Left side:

▲ UP
▼ DOWN

Right side:

◀ LEFT
▶ RIGHT

Center:

Connection Status
       |
      STOP

WebSocket

The browser communicates with the ESP32 using WebSocket.

The WebSocket server runs on port 81.

Phone Browser
      |
      | WebSocket
      v
ws://192.168.4.1:81/

Commands are sent as text.

Browser Command	Internal Command	Action
`UP`	`CMD_FORWARD`	Forward
`DOWN`	`CMD_BACKWARD`	Backward
`LEFT`	`CMD_LEFT`	Turn left
`RIGHT`	`CMD_RIGHT`	Turn right
`STOP`	`CMD_STOP`	Stop

Example:

Phone
  |
  | "UP"
  v
WebSocket
  |
  v
ESP32
  |
  | CMD_FORWARD
  v
Car Task
  |
  v
TB6612FNG
  |
  v
Motors

Button Behaviour

The movement buttons use press-and-release control.

For example:

Finger touches UP
        |
        v
      "UP"
        |
        v
   Car moves forward
        |
        |
Finger releases UP
        |
        v
     "STOP"
        |
        v
     Car stops

This prevents the car from continuing to move after the user releases the movement button.

Dual-Core Architecture

The ESP32 has two CPU cores.

The application separates the web and car-control tasks.

                 ESP32
        +----------------------+
        |                      |
        |      CPU CORES       |
        |                      |
        |  Core 0    Core 1    |
        |    |         |       |
        +----|---------|-------+
             |         |
             v         v
          WEB TASK   CAR TASK

Current task assignment:

Core 0
 |
 +-- Web Task
     |
     +-- HTTP Server
     +-- WebSocket


Core 1
 |
 +-- Car Task
     |
     +-- Motor Control
     +-- TB6612FNG

The networking code does not directly control the motor GPIO pins.

FreeRTOS Command Queue

The web task and car task communicate through a FreeRTOS queue.

                    CORE 0
                      |
                  WebSocket
                      |
                      v
                  "UP"
                      |
                      v
             +----------------+
             | FreeRTOS Queue |
             +-------+--------+
                     |
                     v
                    CORE 1
                     |
                  Car Task
                     |
                     v
               carForward()
                     |
                     v
                 TB6612FNG
                     |
                +----+----+
                |         |
                v         v
              Motor     Motor

The queue separates network handling from hardware control.

This prevents the WebSocket callback from directly manipulating the motor hardware.

Motor Control

The TB6612FNG uses two direction pins for each motor.

For the left motor:

AIN1 = HIGH
AIN2 = LOW

moves in one direction.

AIN1 = LOW
AIN2 = HIGH

moves in the opposite direction.

The right motor works similarly:

BIN1 = HIGH
BIN2 = LOW

and:

BIN1 = LOW
BIN2 = HIGH

The STBY pin must be HIGH for the motor driver to operate.

STBY = HIGH

For the current initial motor test, PWMA and PWMB are held HIGH.

PlatformIO Configuration

platformio.ini:

[env:nodemcu-32s]

platform = espressif32

board = nodemcu-32s

framework = arduino

monitor_speed = 115200

lib_deps =
    links2004/WebSockets

Running the Project

Connect the ESP32 to the computer using USB.

Build and upload the project using PlatformIO.

Open the Serial Monitor:

115200 baud

The ESP32 should display:

================================
     ESP32 WEB CONTROL CAR
================================
[MAIN] Command queue created
[WEB] Running on core 0
[CAR] Running on core 1
[CAR] Motor controller initialized
[WEB] Starting Wi-Fi AP...
[WEB] SSID: ESP32-CAR
[WEB] IP: 192.168.4.1
[WEB] HTTP server started
[WEB] WebSocket started

Connect the phone to:

ESP32-CAR

Password:

esp32car

Then open:

http://192.168.4.1

The web interface should appear.

Testing

For the first motor test, keep the wheels lifted from the ground.

Test each control individually:

UP
DOWN
LEFT
RIGHT
STOP

The Serial Monitor should show messages similar to:

[WS] Client connected

[WS] Command: UP
[CAR] FORWARD

[WS] Command: STOP
[CAR] STOP

[WS] Command: LEFT
[CAR] LEFT

[WS] Command: STOP
[CAR] STOP

After verifying that the controls work correctly, the car can be placed on the floor for controlled testing.

Safety

Always test the car with the wheels lifted from the ground after making wiring or software changes.

Before powering the motor driver:

Check the motor wiring.
Check the common GND.
Check the TB6612FNG connections.
Make sure the car cannot drive into anything.
Keep the emergency STOP control accessible.

The WebSocket disconnect handler also sends a STOP command to the car-control task.

WebSocket connection lost
          |
          v
      CMD_STOP
          |
          v
      Car Task
          |
          v
    Motors stopped

Learning Concepts

This project combines several embedded-system concepts.

ESP32

The ESP32 acts as the main microcontroller.

ESP32
 |
 +-- Wi-Fi
 +-- GPIO
 +-- FreeRTOS
 +-- WebSocket
 +-- C++

TB6612FNG

The TB6612FNG acts as the motor driver.

ESP32
  |
  | Logic signals
  v
TB6612FNG
  |
  | Motor power
  v
DC Motors

GPIO

GPIO pins are used to send digital control signals from the ESP32 to the TB6612FNG.

Wi-Fi

The ESP32 creates its own wireless network.

WebSocket

WebSocket provides a persistent connection between the browser and ESP32.

FreeRTOS

FreeRTOS provides the task and queue system used to separate web handling from car control.

C++

The firmware is written using C++ with the Arduino framework.

Complete System

The complete system can be represented as:

                         PHONE
                           |
                           |
                         Wi-Fi
                           |
                           v
                  +----------------+
                  |     ESP32      |
                  |                |
                  |    CORE 0      |
                  |                |
                  | HTTP/WebSocket |
                  +-------+--------+
                          |
                     Command Queue
                          |
                          v
                  +----------------+
                  |     CORE 1     |
                  |                |
                  |    Car Task    |
                  +-------+--------+
                          |
                       GPIO
                          |
                          v
                  +----------------+
                  |   TB6612FNG    |
                  | Motor Driver   |
                  +-------+--------+
                          |
                   +------+------+
                   |             |
                   v             v
              LEFT MOTOR    RIGHT MOTOR

Current GPIO Map

                ESP32

GPIO 25  ----------> PWMA
GPIO 26  ----------> AIN1
GPIO 27  ----------> AIN2

GPIO 14  ----------> PWMB
GPIO 32  ----------> BIN1
GPIO 33  ----------> BIN2

GPIO 13  ----------> STBY

3.3V     ----------> VCC
GND      ----------> GND

Repository Structure

ESP32_TB6612FNG_Web_controlled_Car/
│
├── platformio.ini
├── README.md
│
└── src/
    │
    ├── main.cpp
    │
    ├── webpage.cpp
    ├── webpage.h
    │
    ├── car.cpp
    └── car.h

Summary

The current system consists of:

ESP32
   |
   | Wi-Fi
   v
Web Browser
   |
   | WebSocket
   v
ESP32
   |
   | FreeRTOS Queue
   v
Car Task
   |
   | GPIO
   v
TB6612FNG
   |
   +------ Left Motor
   |
   +------ Right Motor

The ESP32 successfully receives movement commands through a WebSocket connection and passes those commands to the car-control task, which controls the TB6612FNG motor driver.

Project status: Working

ESP32 TB6612FNG Web Controlled Car

Overview

Current Status

Hardware

Components

Purchase Links

ESP32 NodeMCU-32S

2WD Robot Car Kit

TB6612FNG Dual DC Motor Driver

Hardware Architecture

Wiring

ESP32 to TB6612FNG

Wiring diagram

Motor Connections

Power

Important

Software

Development Environment

Project Structure

main.cpp

webpage.cpp

car.cpp

Wi-Fi

Web Interface

WebSocket

Button Behaviour

Dual-Core Architecture

FreeRTOS Command Queue

Motor Control

PlatformIO Configuration

Running the Project

Testing

Safety

Learning Concepts

ESP32

TB6612FNG

GPIO

Wi-Fi

WebSocket

FreeRTOS

C++

Complete System

Current GPIO Map

Repository Structure

Summary

`main.cpp`

`webpage.cpp`

`car.cpp`