IEIndustrial Automation & Embedded

Smart Library RC Car Assistant

A teleoperated NodeMCU rover that scans book ISBNs with a TTL barcode scanner and queries a Python/Flask mock database over a REST API to return shelving coordinates.

Hardware & Architecture

NodeMCU (ESP8266/ESP32) handling differential-drive motor control, Wi-Fi, and serial comms.
L298N dual H-bridge driving 2–4 DC gear motors for differential-drive kinematics.
UART/TTL barcode scanner (e.g., GM65) for high-speed ISBN capture.
Python backend hosting a mock relational database mapping barcodes to physical shelf locations.

Key Highlights

Distributed architecture splits work between the embedded edge node and a centralized backend.
Onboard web server exposes a simple RC control pad; scanned ISBNs are forwarded to the backend over an HTTP REST call.
Flask backend returns shelving coordinates (Aisle, Shelf, Row) or flags unknown books for manual sorting.

Images

Demonstration of the backend terminal successfully receiving a scanned payload and returning the target shelf location (e.g., 'Book: Robotics & Control | Location: Aisle 4, Row B').

Code

library_car.inoNodeMCU Rover Firmwarecpp

#include <ESP8266WiFi.h>
#include <ESP8266HTTPClient.h>
#include <WiFiClient.h>
#include <SoftwareSerial.h>

// --- Network Configuration ---
const char* ssid = "YOUR_WIFI_SSID";
const char* password = "YOUR_WIFI_PASSWORD";
const String serverName = "http://192.168.1.100:5000/api/scan"; // Update to your PC's IP

// --- Hardware Pins ---
// Motor A (Left)
const int enA = 14; // D5
const int in1 = 12; // D6
const int in2 = 13; // D7
// Motor B (Right)
const int enB = 0;  // D3
const int in3 = 2;  // D4
const int in4 = 15; // D8

// Barcode Scanner (Software Serial keeps Hardware TX/RX free for debugging)
SoftwareSerial barcodeScanner(4, 5); // RX (D2), TX (D1)

WiFiServer server(80);
String header;

void setup() {
  Serial.begin(115200);
  barcodeScanner.begin(9600);
  // Initialize Motor Pins
  pinMode(enA, OUTPUT);
  pinMode(enB, OUTPUT);
  pinMode(in1, OUTPUT);
  pinMode(in2, OUTPUT);
  pinMode(in3, OUTPUT);
  pinMode(in4, OUTPUT);
  // Connect to Wi-Fi
  Serial.print("Connecting to ");
  Serial.println(ssid);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("\nWiFi connected.");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
  server.begin();
}

void loop() {
  // 1. Handle Barcode Scanning
  if (barcodeScanner.available()) {
    String barcodeData = barcodeScanner.readStringUntil('\n');
    barcodeData.trim(); // Remove whitespace/newline
    if (barcodeData.length() > 0) {
      Serial.println("Scanned Barcode: " + barcodeData);
      sendToDatabase(barcodeData);
    }
  }

  // 2. Handle RC Teleoperation (Simple Web Server)
  WiFiClient client = server.available();
  if (client) {
    String currentLine = "";
    while (client.connected()) {
      if (client.available()) {
        char c = client.read();
        header += c;
        if (c == '\n') {
          if (currentLine.length() == 0) {
            // HTTP response
            client.println("HTTP/1.1 200 OK");
            client.println("Content-type:text/html");
            client.println("Connection: close");
            client.println();
            // RC Commands parsed from URL
            if (header.indexOf("GET /forward") >= 0) moveForward();
            else if (header.indexOf("GET /backward") >= 0) moveBackward();
            else if (header.indexOf("GET /left") >= 0) turnLeft();
            else if (header.indexOf("GET /right") >= 0) turnRight();
            else if (header.indexOf("GET /stop") >= 0) stopMotors();
            // Simple HTML Control Pad
            client.println("<!DOCTYPE html><html><body><h1>RC Library Car</h1>");
            client.println("<p><a href=\"/forward\"><button>Forward</button></a></p>");
            client.println("<p><a href=\"/left\"><button>Left</button></a>");
            client.println("<a href=\"/stop\"><button>Stop</button></a>");
            client.println("<a href=\"/right\"><button>Right</button></a></p>");
            client.println("<p><a href=\"/backward\"><button>Backward</button></a></p>");
            client.println("</body></html>");
            client.println();
            break;
          } else {
            currentLine = "";
          }
        } else if (c != '\r') {
          currentLine += c;
        }
      }
    }
    header = "";
    client.stop();
  }
}

// --- Helper Functions ---
void sendToDatabase(String barcode) {
  if (WiFi.status() == WL_CONNECTED) {
    WiFiClient client;
    HTTPClient http;
    // Construct REST Payload
    String serverPath = serverName + "?barcode=" + barcode;
    http.begin(client, serverPath.c_str());
    int httpResponseCode = http.GET();
    if (httpResponseCode > 0) {
      Serial.print("HTTP Response code: ");
      Serial.println(httpResponseCode);
      String payload = http.getString();
      Serial.println("Database Reply: " + payload);
    } else {
      Serial.print("Error code: ");
      Serial.println(httpResponseCode);
    }
    http.end();
  }
}

// Kinematics Control Logic
void moveForward() {
  digitalWrite(in1, HIGH); digitalWrite(in2, LOW);
  digitalWrite(in3, HIGH); digitalWrite(in4, LOW);
  analogWrite(enA, 200); analogWrite(enB, 200);
}
void moveBackward() {
  digitalWrite(in1, LOW); digitalWrite(in2, HIGH);
  digitalWrite(in3, LOW); digitalWrite(in4, HIGH);
  analogWrite(enA, 200); analogWrite(enB, 200);
}
void turnLeft() {
  digitalWrite(in1, LOW); digitalWrite(in2, HIGH);
  digitalWrite(in3, HIGH); digitalWrite(in4, LOW);
  analogWrite(enA, 150); analogWrite(enB, 150);
}
void turnRight() {
  digitalWrite(in1, HIGH); digitalWrite(in2, LOW);
  digitalWrite(in3, LOW); digitalWrite(in4, HIGH);
  analogWrite(enA, 150); analogWrite(enB, 150);
}
void stopMotors() {
  digitalWrite(in1, LOW); digitalWrite(in2, LOW);
  digitalWrite(in3, LOW); digitalWrite(in4, LOW);
  analogWrite(enA, 0); analogWrite(enB, 0);
}

library_server.pyFlask Mock Databasepython

from flask import Flask, request, jsonify

app = Flask(__name__)

# Mock Relational Database (Barcode -> Book Metadata & Location)
library_db = {
    "9780134685991": {
        "title": "Modern Robotics",
        "author": "Kevin M. Lynch",
        "location": "Aisle 3, Shelf B, Row 2"
    },
    "9780262033848": {
        "title": "Introduction to Algorithms",
        "author": "Thomas H. Cormen",
        "location": "Aisle 1, Shelf A, Row 5"
    },
    "1234567890123": {
        "title": "Embedded Systems Design",
        "author": "Steve Heath",
        "location": "Aisle 4, Shelf C, Row 1"
    }
}


@app.route('/api/scan', methods=['GET'])
def handle_scan():
    barcode = request.args.get('barcode')
    if not barcode:
        return jsonify({"error": "No barcode provided"}), 400
    print(f"[SYSTEM] Received Scan Request for Barcode: {barcode}")
    if barcode in library_db:
        book_info = library_db[barcode]
        print(f"[SUCCESS] Match Found: {book_info['title']} -> {book_info['location']}")
        return jsonify({
            "status": "success",
            "data": book_info
        }), 200
    else:
        print("[WARNING] Barcode not recognized in current database.")
        return jsonify({
            "status": "error",
            "message": "Book not found in database. Requires manual sorting."
        }), 404


if __name__ == '__main__':
    # Run on 0.0.0.0 to allow incoming connections from the NodeMCU on the local network
    app.run(host='0.0.0.0', port=5000, debug=True)