This project enables a user to control a robot car using a PlayStation 3 (PS3) controller via an MQTT protocol. The system consists of a PS3 controller, a computer running a Python script to read joystick inputs and send MQTT messages, and an ESP8266-based car that receives and processes the MQTT messages to move accordingly.

1. ESP8266 NodeMCU (to control the motors and communicate via MQTT)
2. L298N Motor Driver Module (to control the DC motors)
3. Two DC Motors (for movement)
4. Power Supply (Battery pack for the motors and ESP8266)
5. PlayStation 3 Controller (to control the car)
6. Computer (to run the Python script for joystick input and MQTT communication)
7. Jumper Wires (to connect all components)

• Connect ESP8266 to L298N motor driver using the above table.
• Connect the PS3 controller to the computer via USB or Bluetooth.
• Power the ESP8266 using a battery pack (5V recommended).

This project consists of two main parts:

1. Python Code (on the computer) to read PS3 joystick input and publish MQTT messages.
2. C++ Code (Arduino) (on the ESP8266) to receive and process MQTT messages to control the motors.

import paho.mqtt.client as mqtt
import hid  # To read input from PS3 Controller
import time

• paho.mqtt.client: Handles MQTT communication.
• hid: Reads input from the PS3 controller.
• time: Provides delay functionality.

BROKER = "broker.emqx.io"
TOPIC = "IoT/example"

• BROKER: The MQTT broker address.
• TOPIC: The topic to which movement commands are published.

def on_disconnect(client, userdata, rc):
    print("Disconnected, trying to reconnect...")
    while True:
        try:
            client.reconnect()
            break
        except:
            time.sleep(5)

• This function ensures that if the MQTT connection is lost, the client will continuously attempt to reconnect every 5 seconds.

client = mqtt.Client()
client.on_disconnect = on_disconnect
client.connect(BROKER, 1883, 60)
client.loop_start()  # start loop MQTT

• Creates an MQTT client.
• Assigns the on_disconnect function.
• Connects to the broker on port 1883 with a keep-alive of 60 seconds.
• Starts the MQTT loop to keep the connection alive.

Below is a detailed explanation of each part of the C++ code running on the ESP8266:

#include <ESP8266WiFi.h>
#include <PubSubClient.h>

• ESP8266WiFi.h: Connects ESP8266 to the WiFi network.
• PubSubClient.h: Enables MQTT communication with the broker.

const char* ssid = "your_wifi_ssid";
const char* password = "your_wifi_password";
const char* mqtt_server = "broker.emqx.io";

• ssid: WiFi network name.
• password: WiFi password.
• mqtt_server: MQTT broker address.

#define MOTOR_A1 D1
#define MOTOR_A2 D2
#define MOTOR_B1 D3
#define MOTOR_B2 D4
#define ENA D0
#define ENB D5
#define LED_STOP D7
#define LED_MOVE D8

• Defines the pins used to control motors and indicator LEDs.

WiFiClient espClient;
PubSubClient client(espClient);

• Creates WiFi and MQTT client objects.

void setup_wifi() {
    delay(10);
    Serial.println("Connecting to WiFi...");
    WiFi.begin(ssid, password);
    while (WiFi.status() != WL_CONNECTED) {
        delay(500);
        Serial.print(".");
    }
    Serial.println("WiFi connected");
}

• Initiates connection to the WiFi network and waits until it is successfully connected.

void callback(char* topic, byte* payload, unsigned int length) {
    String message = "";
    for (int i = 0; i < length; i++) {
        message += (char)payload[i];
    }
    if (message == "forward") { moveForward(); }
    else if (message == "backward") { moveBackward(); }
    else if (message == "left") { turnLeft(); }
    else if (message == "right") { turnRight(); }
    else { stopMotor(); }
}

• Receives commands from MQTT and executes the corresponding movement function.

void setup() {
    Serial.begin(115200);
    setup_wifi();
    client.setServer(mqtt_server, 1883);
    client.setCallback(callback);
}

• Initializes serial communication, WiFi connection, and MQTT setup.

void loop() {
    if (!client.connected()) {
        reconnect();
    }
    client.loop();
}

• Ensures ESP8266 remains connected to the MQTT broker and processes incoming messages.

• Implement WebSocket control.
• Add voice command support.
• Add a camera module for remote vision.

Enjoy controlling your car wirelessly with a PS3 controller and MQTT!