🤖 Voice-Enabled Robot Car with VC-02 LoRa Control & OLED Display

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📌 1. Introduction

Enhancing the previous design, an OLED display is added to the transmitter (master node) to:

• Display the recognized voice command in real time
• Provide visual feedback before sending the command
• Improve usability in noisy environments

The rest of the system remains the same: voice commands recognized by VC-02 → transmitted via LoRa → robot car executes commands.

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🎯 2. Additional Hardware for Transmitter

• 0.96" or 1.3" OLED display (I2C, SSD1306)
• SDA → ESP32 GPIO (e.g., 21)
• SCL → ESP32 GPIO (e.g., 22)
• 3.3V and GND

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🔌 3. Updated System Architecture

1. Master Node (Transmitter)

   • VC-02 voice recognition module
   • OLED display for command visualization
   • LoRa module (RA-08H) for transmitting commands

2. Robot Car Node (Slave)

   • ESP32 receives LoRa commands
   • Controls motors through motor driver

3. Dashboard / Status (Optional)

   • Central logging of commands and robot status

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📜 4. Updated Master Node Code (ESP32 + VC-02 + OLED)

#include <Wire.h>
#include <Adafruit_SSD1306.h>
#include <SoftwareSerial.h>
#include <LoRa.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

SoftwareSerial vc02(4, 5); // RX, TX to VC-02

void setup() {
  Serial.begin(115200);
  vc02.begin(9600);
  
  // Initialize OLED
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println("OLED init failed");
    while(true);
  }
  display.clearDisplay();
  display.setTextSize(2);
  display.setTextColor(WHITE);
  display.setCursor(0,0);
  display.println("Voice Car");
  display.display();

  // Initialize LoRa
  LoRa.begin(915E6);
}

void loop() {
  if(vc02.available()){
    String command = vc02.readStringUntil('\n');
    command.trim();
    
    // Display on OLED
    display.clearDisplay();
    display.setCursor(0,0);
    display.setTextSize(2);
    display.println("Cmd:");
    display.setTextSize(2);
    display.setCursor(0, 30);
    display.println(command);
    display.display();

    // Send via LoRa
    LoRa.beginPacket();
    LoRa.print(command);
    LoRa.endPacket();

    Serial.println("Sent Command: " + command);
    delay(1000);
  }
}

Robot Car Node (Slave)

#include <LoRa.h>
#define MOTOR_LEFT_FORWARD 14
#define MOTOR_LEFT_BACK 12
#define MOTOR_RIGHT_FORWARD 27
#define MOTOR_RIGHT_BACK 26

void setup() {
  Serial.begin(115200);
  LoRa.begin(915E6);
  pinMode(MOTOR_LEFT_FORWARD, OUTPUT);
  pinMode(MOTOR_LEFT_BACK, OUTPUT);
  pinMode(MOTOR_RIGHT_FORWARD, OUTPUT);
  pinMode(MOTOR_RIGHT_BACK, OUTPUT);
}

void loop() {
  int packetSize = LoRa.parsePacket();
  if(packetSize){
    String command = LoRa.readString();
    Serial.println("Received Command: " + command);

    if(command == "FORWARD"){
      digitalWrite(MOTOR_LEFT_FORWARD, HIGH);
      digitalWrite(MOTOR_RIGHT_FORWARD, HIGH);
    } 
    else if(command == "BACK"){
      digitalWrite(MOTOR_LEFT_BACK, HIGH);
      digitalWrite(MOTOR_RIGHT_BACK, HIGH);
    } 
    else if(command == "LEFT"){
      digitalWrite(MOTOR_LEFT_BACK, HIGH);
      digitalWrite(MOTOR_RIGHT_FORWARD, HIGH);
    } 
    else if(command == "RIGHT"){
      digitalWrite(MOTOR_LEFT_FORWARD, HIGH);
      digitalWrite(MOTOR_RIGHT_BACK, HIGH);
    } 
    else if(command == "STOP"){
      digitalWrite(MOTOR_LEFT_FORWARD, LOW);
      digitalWrite(MOTOR_LEFT_BACK, LOW);
      digitalWrite(MOTOR_RIGHT_FORWARD, LOW);
      digitalWrite(MOTOR_RIGHT_BACK, LOW);
    }
  }
}

🔎 Working Principle

The voice-enabled robot car with OLED feedback and LoRa control works as follows:

1. Voice Command Recognition

   • The VC-02 module on the transmitter recognizes predefined voice commands such as “Forward”, “Left”, “Right”, and “Stop”.

2. Visual Feedback on OLED

   • The recognized command is displayed on the OLED screen in real time, providing visual confirmation before transmission.

3. LoRa Transmission

   • The command is transmitted wirelessly via the RA-08H LoRa module from the master (transmitter) node to the robot car (slave node).
   • LoRa ensures long-range, low-power communication without Wi-Fi or Bluetooth.

4. Command Reception and Motor Control

   • The robot car receives the command via LoRa.
   • The ESP32 interprets the command and drives the motors through a motor driver (e.g., L298N) to execute the action.

5. Optional Feedback

   • The robot can transmit status updates (e.g., movement state, battery level) back to the master node or dashboard for monitoring.

6. Continuous Operation

   • This process repeats, enabling real-time, voice-controlled navigation of the robot car.

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🏁 Conclusion

The voice-enabled robot car with VC-02, OLED display, and LoRa control demonstrates:

• Real-time voice-controlled navigation of a mobile robot.
• Visual confirmation of commands via the OLED display, enhancing usability.
• Long-range, low-power wireless communication using LoRa for remote control.
• Integration of speech recognition, embedded control, and IoT communication in a single system.
• Practical application for remote robotics, IoT learning, and intelligent automation projects.

This system serves as a hands-on example of combining voice recognition, visual feedback, and wireless robotics control for engineering students and IoT enthusiasts.