Arduino Project
Radar Guard 6.0
Course Introduction
This project uses an ultrasonic sensor, a servo motor, and an Arduino to build a radar system with LCD and OLED displays.
The servo scans for obstacles, showing distance and angle data on both screens with a semicircle radar view. If an object is closer than the set threshold, a red LED and buzzer alert; otherwise, a green LED indicates a clear path.
Note
If this is your first time working with an Arduino project, we recommend downloading and reviewing the basic materials first.
1.1 Install Arduino IDE(Important)
1.2 Introduction of Arduino IDE
Required Components
In this project, we need the following components:
Wiring
Common Connections:
LED
Red LED: Connect the LEDs anode to the 4 on Arduino, and the LEDs cathode to a 220Ω resistor then to negative power bus on the breadboard.
Green LED: Connect the LEDs anode to the 5 on Arduino, and the LEDs cathode to a 220Ω resistor then to negative power bus on the breadboard.
Digital Servo Motor
Connect to breadboard’s positive power bus.
Connect to breadboard’s negative power bus.
Connect to 9 on the Arduino.
Active Buzzer
＋: Connect to 6 on the Arduino.
－: Connect to breadboard’s negative power bus.
I2C LCD 1602
SDA: Connect to A4 on the Arduino.
SCL: Connect to A5 on the Arduino.
GND: Connect to breadboard’s negative power bus.
VCC: Connect to breadboard’s red power bus.
Ultrasonic Sensor Module
Trig: Connect to 2 on the Arduino.
Echo: Connect to 3 on the Arduino.
GND: Connect to breadboard’s negative power bus.
VCC: Connect to breadboard’s red power bus.
OLED Display Module
SDA: Connect to SDA on the Arduino.
SCK: Connect to SCL on the Arduino.
GND: Connect to breadboard’s negative power bus.
VCC: Connect to breadboard’s red power bus.
Writing the Code
Note
You can copy this code into Arduino IDE.
To install the library, use the Arduino Library Manager and search for LiquidCrystal I2C and Adafruit GFX and Adafruit SSD1306 and install it.
Don’t forget to select the board(Arduino UNO R4 Minima/WIFI) and the correct port before clicking the Upload button.
#include
#include
#include
#include
#include
// --- Servo & Ultrasonic ---
Servo servo;
const int trigPin = 2;
const int echoPin = 3;
// --- LED & Buzzer ---
const int ledGreen = 4;
const int ledRed = 5;
const int buzzer = 6;
// --- LCD (0x27 or 0x3F) ---
LiquidCrystal_I2C lcd(0x27, 16, 2);
// --- OLED (0x3C) ---
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);
// --- Parameters ---
int angle = 0;
long distance = 0;
const int DETECT_THRESHOLD = 20; // cm
// --- Distance measurement function ---
long getDistance() {
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
long duration = pulseIn(echoPin, HIGH, 30000); // 30ms timeout
if (duration == 0) return 999; // timeout handling
return duration * 0.034 / 2; // cm
}
void setup() {
Serial.begin(9600);
servo.attach(9);
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
pinMode(ledGreen, OUTPUT);
pinMode(ledRed, OUTPUT);
pinMode(buzzer, OUTPUT);
// LCD
lcd.init();
lcd.backlight();
// OLED
if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
for (;;); // stop if initialization fails
}
display.clearDisplay();
display.display();
}
void loop() {
// Left to right
for (angle = 0; angle <= 180; angle += 3) {
servo.write(angle);
delay(30);
distance = getDistance();
radarAction(distance);
drawRadar(angle, distance);
}
// Right to left
for (angle = 180; angle >= 0; angle -= 3) {
servo.write(angle);
delay(30);
distance = getDistance();
radarAction(distance);
drawRadar(angle, distance);
}
}
// --- Buzzer/LED/LCD display control ---
void radarAction(long d) {
lcd.clear();
if (d < DETECT_THRESHOLD && d > 0) {
digitalWrite(ledRed, HIGH);
digitalWrite(ledGreen, LOW);
digitalWrite(buzzer, HIGH);
lcd.setCursor(0, 0);
lcd.print("Detected Object");
lcd.setCursor(0, 1);
lcd.print("Dist: ");
lcd.print(d);
lcd.print(" cm");
} else {
digitalWrite(ledRed, LOW);
digitalWrite(ledGreen, HIGH);
digitalWrite(buzzer, LOW);
lcd.setCursor(0, 0);
lcd.print("No Object");
lcd.setCursor(0, 1);
lcd.print("Dist: ");
lcd.print(d);
lcd.print(" cm");
}
}
// --- OLED semicircle radar drawing ---
void drawRadar(int angle, long d) {
display.clearDisplay();
int centerX = SCREEN_WIDTH / 2;
int centerY = SCREEN_HEIGHT - 1;
// --- Semicircle concentric circles ---
for (int r = 15; r <= 60; r += 15) {
display.drawCircle(centerX, centerY, r, SSD1306_WHITE);
}
// --- Radius lines ---
for (int a = 0; a <= 180; a += 30) {
float rad = radians(a);
int x = centerX + cos(rad) * 60;
int y = centerY - sin(rad) * 60;
display.drawLine(centerX, centerY, x, y, SSD1306_WHITE);
}
// --- Scanning line ---
float rad = radians(angle);
int x2 = centerX + cos(rad) * 60;
int y2 = centerY - sin(rad) * 60;
display.drawLine(centerX, centerY, x2, y2, SSD1306_WHITE);
// --- Detected target point ---
if (d < 60) {
int tx = centerX + cos(rad) * d;
int ty = centerY - sin(rad) * d;
display.fillCircle(tx, ty, 2, SSD1306_WHITE);
}
// --- Angle/Distance text ---
display.setTextSize(1);
display.setTextColor(SSD1306_WHITE);
display.setCursor(0, 0);
display.print("Ang:");
display.print(angle);
display.print(" D:");
display.print(d);
display.display();
}