Arduino Project
Radar Guard 10.0
Course Introduction
In this lesson, you’ll build an ultrasonic safety scanner using a servo, LEDs, and a buzzer. The servo sweeps the ultrasonic sensor to detect distance, while the LEDs change from green to yellow to red based on how close an object is. In danger zones, the buzzer sounds an alert with different beeping patterns.
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:
Traffic light LED
R: Connect to 2 on the Arduino.
Y: Connect to 3 on the Arduino.
G: Connect to 4 on the Arduino.
GND: Connect to GND on the Arduino.
Digital Servo Motor
Connect to breadboard’s positive power bus.
Connect to breadboard’s negative power bus.
Connect to 12 on the Arduino.
Buzzer Modudle
I/O: Connect to 5 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 11 on the Arduino.
Echo: Connect to 10 on the Arduino.
GND: Connect to breadboard’s negative power bus.
VCC: Connect to breadboard’s red power bus.
Writing the Code
Note
Build the circuit.
Upload the code to the Arduino board using Arduino IDE.
In the Arduino IDE, check the current Arduino port(COMx).
To install the library, use the Arduino Library Manager and search for LiquidCrystal_I2C and install it.
The ArduinoRadarGUI is used here. You can click here Radar_Guard9.0.zip to download it.
Open ArduinoLidarGUI.pde in the Processing IDE .
Modify the code in line 35 to ensure the correct port number(COMx).
Run the Processing sketch to visualize the radar data.
#include
// ------------ Pin Definitions ------------
const int trigPin = 11; // Ultrasonic Trig pin
const int echoPin = 10; // Ultrasonic Echo pin
const int servoPin = 12; // Servo signal pin
const int buzzerPin = 5; // Passive buzzer
const int greenLED = 2; // Traffic light - Green
const int yellowLED = 3; // Traffic light - Yellow
const int redLED = 4; // Traffic light - Red
// ------------ Servo Settings ------------
const int minAngle = 0; // Servo minimum angle
const int maxAngle = 180; // Servo maximum angle
const int stepAngle = 1; // Servo movement step
int currentAngle = minAngle;
int direction = 1; // +1 for forward, -1 for backward
// ------------ Distance Thresholds ------------
const int thresholdYellowCM = 30; // ≤30cm = Yellow zone
const int thresholdRedCM = 15; // ≤15cm = Red zone
// ------------ Buzzer Control ------------
bool buzzerEnabled = false;
unsigned long nextBuzzTime = 0;
int buzzerFreq = 2000; // Default beep frequency
int buzzOnMs = 80;
int buzzOffMs = 200;
bool buzzing = false;
// ------------ Timing ------------
unsigned long nextServoMove = 0;
const uint16_t servoStepInterval = 20;
// ------------ Servo Object ------------
Servo scanner;
// ------------ Measure distance (cm) ------------
long measureDistanceCM() {
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
unsigned long duration = pulseIn(echoPin, HIGH, 20000); // timeout 20ms
if (duration == 0) return 9999; // No echo
long distance = duration / 58.0;
if (distance <= 0) distance = 9999;
return distance;
}
// ------------ Update LEDs + Buzzer by distance ------------
void updateStateByDistance(long dist) {
// ---- Red zone ----
if (dist <= thresholdRedCM) {
digitalWrite(redLED, HIGH);
digitalWrite(yellowLED, LOW);
digitalWrite(greenLED, LOW);
buzzerEnabled = true;
buzzerFreq = 2800; // Danger tone
buzzOnMs = 120;
buzzOffMs = 120;
}
// ---- Yellow zone ----
else if (dist <= thresholdYellowCM) {
digitalWrite(redLED, LOW);
digitalWrite(yellowLED, HIGH);
digitalWrite(greenLED, LOW);
buzzerEnabled = true;
buzzerFreq = 2000; // Warning tone
buzzOnMs = 80;
buzzOffMs = 250;
}
// ---- Green zone ----
else {
digitalWrite(redLED, LOW);
digitalWrite(yellowLED, LOW);
digitalWrite(greenLED, HIGH);
buzzerEnabled = false;
noTone(buzzerPin);
}
}
// ------------ Non-blocking buzzer scheduler ------------
void updateBuzzer(unsigned long now) {
if (!buzzerEnabled) {
buzzing = false;
noTone(buzzerPin);
return;
}
if (now >= nextBuzzTime) {
if (!buzzing) {
tone(buzzerPin, buzzerFreq);
buzzing = true;
nextBuzzTime = now + buzzOnMs;
} else {
noTone(buzzerPin);
buzzing = false;
nextBuzzTime = now + buzzOffMs;
}
}
}
// ------------ Setup ------------
void setup() {
Serial.begin(9600);
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
pinMode(buzzerPin, OUTPUT);
pinMode(greenLED, OUTPUT);
pinMode(yellowLED, OUTPUT);
pinMode(redLED, OUTPUT);
// Initial LED state
digitalWrite(greenLED, HIGH);
digitalWrite(yellowLED, LOW);
digitalWrite(redLED, LOW);
// Servo init
scanner.attach(servoPin);
scanner.write(currentAngle);
nextServoMove = millis();
nextBuzzTime = millis();
}
// ------------ Main Loop ------------
void loop() {
unsigned long now = millis();
// ------ Servo movement control ------
if (now >= nextServoMove) {
nextServoMove = now + servoStepInterval;
currentAngle += direction * stepAngle;
if (currentAngle >= maxAngle) {
currentAngle = maxAngle;
direction = -1;
}
else if (currentAngle <= minAngle) {
currentAngle = minAngle;
direction = 1;
}
scanner.write(currentAngle);
long dist = measureDistanceCM();
updateStateByDistance(dist);
// Send angle + distance to Processing GUI
Serial.print(currentAngle);
Serial.print(",");
Serial.print(dist);
Serial.print(".");
}
// ------ Update buzzer (non-blocking) ------
updateBuzzer(now);
}