RC Robot using ESP8266 (Wemos D1 Mini) with Ultrasonic Obstacle Avoidance
Overview
This project is a WiFi-controlled robotic car built using the ESP8266-based Wemos D1 Mini. It supports both manual control through a web interface and autonomous obstacle avoidance using an ultrasonic sensor.
The robot creates its own WiFi hotspot, allowing any smartphone or laptop to connect and control it directly via a browser without requiring a dedicated mobile application.
Features
- WiFi Access Point mode (no router required)
- Web-based control interface
- Manual control (forward, backward, left, right, stop)
- Autonomous obstacle avoidance mode
- Real-time response
- Simple and low-cost hardware setup
Hardware Requirements
- Wemos D1 Mini (ESP8266)
- HC-SR04 Ultrasonic Sensor
- L298N Motor Driver Module
- 2 DC Motors with wheels
- Robot chassis
- Battery pack (7.4V or 9V recommended)
- Jumper wires
Pin Configuration
Ultrasonic Sensor
| Sensor Pin | Wemos D1 Mini |
|---|
| VCC | 5V |
| GND | GND |
| TRIG | D5 |
| ECHO | D6 |
Motor Driver (L298N)
| L298N Pin | Wemos Pin |
|---|
| IN1 | D1 |
| IN2 | D2 |
| IN3 | D3 |
| IN4 | D4 |
| ENA | D7 |
| ENB | D8 |
How It Works
Manual Mode
- User connects to robot WiFi
- Opens web interface
- Sends movement commands
- Robot responds instantly
Auto Mode
Getting Started
1. Upload Code
- Open Arduino IDE
- Select board: Wemos D1 Mini (ESP8266)
- Upload the provided code
2. Power the Robot
- Use battery pack or external power supply
3. Connect to WiFi
- SSID:
RC_Robot
- Password:
12345678
4. Open Web Interface
Open browser and go to:
http://192.168.4.1
Project Structure
RC-Robot-ESP8266/
- robot_code.ino
- README.md
- circuit_diagram.png
- robot_image.jpg
Applications
- Robotics learning projects
- IoT-based vehicle control
- Obstacle avoidance systems
- Educational demonstrations
Future Improvements
- Mobile app control (Android / iOS)
- Camera integration for live streaming
- Voice command support
- AI-based navigation
- Line following feature
License
This project is open-source and free to use for educational and personal purposes.
Author
Developed as a DIY IoT robotics project using ESP8266 and basic electronic components.
Source Code
#include <ESP8266WiFi.h>
#include <ESP8266WebServer.h>
// Motor Pins
#define IN1 D1
#define IN2 D2
#define IN3 D3
#define IN4 D4
#define ENA D7
#define ENB D8
// Ultrasonic Pins
#define TRIG D5
#define ECHO D6
ESP8266WebServer server(80);
bool autoMode = false;
// WiFi credentials
const char* ssid = "RC_Robot";
const char* password = "12345678";
// Distance function
long getDistance() {
digitalWrite(TRIG, LOW);
delayMicroseconds(2);
digitalWrite(TRIG, HIGH);
delayMicroseconds(10);
digitalWrite(TRIG, LOW);
long duration = pulseIn(ECHO, HIGH);
long distance = duration * 0.034 / 2;
return distance;
}
// Motor functions
void stopMotors() {
digitalWrite(IN1, LOW); digitalWrite(IN2, LOW);
digitalWrite(IN3, LOW); digitalWrite(IN4, LOW);
}
void forward() {
digitalWrite(IN1, HIGH); digitalWrite(IN2, LOW);
digitalWrite(IN3, HIGH); digitalWrite(IN4, LOW);
}
void backward() {
digitalWrite(IN1, LOW); digitalWrite(IN2, HIGH);
digitalWrite(IN3, LOW); digitalWrite(IN4, HIGH);
}
void left() {
digitalWrite(IN1, LOW); digitalWrite(IN2, HIGH);
digitalWrite(IN3, HIGH); digitalWrite(IN4, LOW);
}
void right() {
digitalWrite(IN1, HIGH); digitalWrite(IN2, LOW);
digitalWrite(IN3, LOW); digitalWrite(IN4, HIGH);
}
// Web Handlers
void handleRoot() {
String html = R"rawliteral(
<!DOCTYPE html>
<html>
<head>
<title>Robot Control</title>
<style>
body { text-align:center; font-family:Arial; background:#222; color:white; }
button { width:120px; height:50px; margin:10px; font-size:16px; }
</style>
</head>
<body>
<h2>Robot Control</h2>
<button onclick="fetch('/auto')">AUTO MODE</button>
<button onclick="fetch('/manual')">MANUAL MODE</button><br>
<button onclick="fetch('/forward')">FORWARD</button><br>
<button onclick="fetch('/left')">LEFT</button>
<button onclick="fetch('/stop')">STOP</button>
<button onclick="fetch('/right')">RIGHT</button><br>
<button onclick="fetch('/backward')">BACKWARD</button>
</body>
</html>
)rawliteral";
server.send(200, "text/html", html);
}
void setupRoutes() {
server.on("/", handleRoot);
server.on("/forward", []() {
autoMode = false;
forward();
server.send(200, "text/plain", "Forward");
});
server.on("/backward", []() {
autoMode = false;
backward();
server.send(200, "text/plain", "Backward");
});
server.on("/left", []() {
autoMode = false;
left();
server.send(200, "text/plain", "Left");
});
server.on("/right", []() {
autoMode = false;
right();
server.send(200, "text/plain", "Right");
});
server.on("/stop", []() {
autoMode = false;
stopMotors();
server.send(200, "text/plain", "Stop");
});
server.on("/auto", []() {
autoMode = true;
server.send(200, "text/plain", "Auto Mode");
});
server.on("/manual", []() {
autoMode = false;
stopMotors();
server.send(200, "text/plain", "Manual Mode");
});
server.begin();
}
void setup() {
pinMode(IN1, OUTPUT); pinMode(IN2, OUTPUT);
pinMode(IN3, OUTPUT); pinMode(IN4, OUTPUT);
pinMode(ENA, OUTPUT); pinMode(ENB, OUTPUT);
pinMode(TRIG, OUTPUT);
pinMode(ECHO, INPUT);
analogWrite(ENA, 800);
analogWrite(ENB, 800);
WiFi.softAP(ssid, password);
setupRoutes();
}
void loop() {
server.handleClient();
if (autoMode) {
long distance = getDistance();
if (distance < 20) {
stopMotors();
delay(300);
backward();
delay(500);
right();
delay(400);
} else {
forward();
}
}
}
