By Paul , 15 September 2025

Simple Arduino Radar with Processing - Step by Step Guide

Why This Approach is Much Easier

✅ Only 3 components - Arduino Mega, servo, ultrasonic sensor
✅ No complex TFT display wiring - uses your computer screen instead
✅ Easy troubleshooting - see data in real-time
✅ Professional radar display - looks just as good as TFT version
✅ Works on any computer - no special hardware needed

Components Needed (Only 3!)

Component	Purpose	Notes
Arduino Mega 2560	Main controller	Any Arduino Mega will work
HC-SR04 Ultrasonic Sensor	Distance measurement	Very common, cheap sensor
SG90 Servo Motor	Rotates the sensor	Standard 9g servo
Jumper wires	Connections	Male-to-male, about 10 wires
USB cable	Arduino connection	Usually comes with Arduino

Total cost: About $20-25

Super Simple Wiring (Only 6 Wires!)

Arduino Mega Pin Connections

Component	Wire Color	Arduino Pin
Servo
Red (Power)		5V
Brown/Black (Ground)		GND
Orange (Signal)		Pin 6
Ultrasonic Sensor
VCC (Power)	Red	5V
GND (Ground)	Black	GND
TRIG (Trigger)	Any color	Pin 9
ECHO (Echo)	Any color	Pin 10

Visual Wiring Guide

Arduino Mega
┌─────────────────┐
│  ╔═══════════╗  │
│  ║ USB PORT  ║  │     Servo Motor
│  ╚═══════════╝  │     ┌─────────┐
│                 │     │  ┌───┐  │
│  Pin 6  ────────┼─────┤  │ ● │  │ ← Ultrasonic mounted here
│  Pin 9  ────────┼───┐ │  └───┘  │
│  Pin 10 ────────┼─┐ │ └─────────┘
│  5V     ────────┼─┼─┼─── Red wires (Power)
│  GND    ────────┼─┼─┼─── Black wires (Ground)
└─────────────────┘ │ │
    Ultrasonic      │ │
    ┌─────────────┐ │ │
    │ TRIG ECHO   │ │ │
    │  │    │     │ │ │
    │  └────┼─────┘ │ │
    │       └───────┘ │
    └─────────────────┘

Step 1: Physical Assembly (15 minutes)

Mount Ultrasonic Sensor to Servo

Attach the ultrasonic sensor to the servo horn (white plastic piece)
Use small screws or strong double-sided tape
Ensure sensor faces forward when servo is at center position
Mount servo to a stable base (breadboard, cardboard, etc.)

Make Connections

Connect servo wires:
- Red → 5V on Arduino
- Brown/Black → GND on Arduino
- Orange → Pin 6 on Arduino
Connect ultrasonic sensor:
- VCC → 5V on Arduino
- GND → GND on Arduino
- TRIG → Pin 9 on Arduino
- ECHO → Pin 10 on Arduino
Double-check all connections before powering on

Step 2: Install Software (10 minutes)

Download Processing

Go to https://processing.org/download
Download Processing for your operating system
Install and open Processing

Prepare Arduino IDE

Open Arduino IDE
Select Tools → Board → "Arduino Mega or Mega 2560"
Select Tools → Port → (your Arduino's COM port)

Step 3: Upload Arduino Code (5 minutes)

Copy the Arduino code from the "Simple Arduino Radar Code" above
Paste into Arduino IDE
Click Upload (arrow button)
Wait for "Done uploading" message

Test Arduino is Working

Open Serial Monitor (Tools → Serial Monitor)
Set baud rate to 9600
You should see data like: 0,45 then 2,47 then 4,52 etc.
Watch servo move from 0° to 180° and back

If this doesn't work, STOP HERE and let me know what's happening!

Step 4: Run Processing Display (5 minutes)

Copy the Processing code from "Simple Processing Radar Display Code" above
Open Processing and paste the code
Click the Play button (triangle)

Fix Serial Port Connection

If you get an error about serial ports:

Look at the console output in Processing
Find your Arduino port in the list (usually COM3, COM4 on Windows)
Change line 23 in the Processing code:
```
myPort = new Serial(this, Serial.list()[0], 9600);
```
Replace [0] with the correct number from the list
Run again

Step 5: Enjoy Your Working Radar! 🎉

You should now see:

✅ Green radar screen with distance circles and angle lines
✅ Bright green sweep line rotating back and forth
✅ Red dots appearing when objects are detected
✅ Live information showing current angle and distance
✅ "CONNECTED" status in green

Testing Your Radar

Test Object Detection

Place objects at different distances in front of the sensor
Watch red dots appear on the radar display
Move objects around and see them tracked in real-time
Try different sized objects - bigger objects show up better

Keyboard Controls

Press 'C' - Clear all detected objects from display
Press 'R' - Reconnect to Arduino if connection is lost

Troubleshooting Common Issues

Problem: Arduino Serial Monitor shows no data

Solutions:

Check servo and sensor power connections (5V and GND)
Verify TRIG → Pin 9, ECHO → Pin 10
Try different USB cable
Restart Arduino IDE

Problem: Processing can't connect to serial port

Solutions:

Close Arduino Serial Monitor first
Check which COM port Arduino is using (Tools → Port)
Change the [0] in Processing code to correct port number
Try running Processing as administrator

Problem: Servo doesn't move smoothly

Solutions:

Use external 9V power adapter for Arduino
Check servo power connections
Ensure servo isn't mechanically blocked

Problem: No objects detected

Solutions:

Test sensor with hand in front at different distances
Check TRIG and ECHO pin connections
Ensure sensor faces straight ahead
Try larger objects (books, boxes work well)

Customization Options

Adjust Scanning Speed

delay(100);  // Change to 50 for faster, 200 for slower

Change Angle Step Size

angle += direction * 2;  // Change 2 to 1 for smoother, 5 for faster

Modify Detection Range

if (distance > 2 && distance < 200) {  // Change 200 to desired max range

Change Radar Colors in Processing

stroke(0, 255, 0);     // Green - change to stroke(255, 0, 0) for red
fill(255, 0, 0);       // Red objects - change to fill(0, 0, 255) for blue

Why This Approach is Better for Learning

✅ Immediate feedback - see exact distance readings
✅ Easy debugging - watch data in real-time
✅ Professional results - looks like real radar systems
✅ Less complexity - fewer things to go wrong
✅ Expandable - easy to add features later

This gives you a fully functional radar system that's perfect for demonstrations, learning, and impressing friends!

Next Steps (Advanced)

Once this works perfectly, you can:

Add sound effects when objects are detected
Log data to files for analysis
Add multiple sensors for wider coverage
Create a web interface to view remotely
Add object tracking to follow moving targets

But first, let's get the basic version working perfectly!

Comments4

ARDUINO CODE (Upload this to your Arduino Mega first)

#include <Servo.h>

// Create servo object
Servo radarServo;

// Define pins - ONLY 3 connections needed!
const int trigPin = 9;
const int echoPin = 10;
const int servoPin = 6;

// Variables
int angle = 0;
int direction = 1; // 1 for forward, -1 for backward

void setup() {
// Initialize serial communication
Serial.begin(9600);

// Initialize pins
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);

// Attach servo
radarServo.attach(servoPin);

// Move servo to starting position
radarServo.write(0);
delay(1000);

Serial.println("Simple Radar Started");
}

void loop() {
// Move servo to current angle
radarServo.write(angle);
delay(50); // Wait for servo to reach position

// Measure distance
int distance = measureDistance();

// Send data to Processing in format: angle,distance
Serial.print(angle);
Serial.print(",");
Serial.println(distance);

// Update angle for next iteration
angle += direction * 2; // Move 2 degrees at a time

// Change direction when reaching limits
if (angle >= 180) {
direction = -1;
angle = 180;
} else if (angle <= 0) {
direction = 1;
angle = 0;
}

delay(100); // Delay between measurements
}

int measureDistance() {
// Clear the trigPin
digitalWrite(trigPin, LOW);
delayMicroseconds(2);

// Send 10 microsecond pulse
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);

// Read the echo pin
long duration = pulseIn(echoPin, HIGH);

// Calculate distance in cm
int distance = duration * 0.034 / 2;

// Limit maximum distance reading
if (distance > 200 || distance < 2) {
distance = 200; // Return max distance if no valid reading
}

return distance;
}

🔵 PROCESSING CODE (Run this on your computer after Arduino work

import processing.serial.*;

Serial myPort;
String data = "";
int angle = 0;
int distance = 0;

// Radar display settings
int centerX, centerY;
int maxRadius = 300;
ArrayList<PVector> objects;

void setup() {
size(800, 600);

// Set radar center
centerX = width / 2;
centerY = height - 80;

// Initialize objects list
objects = new ArrayList<PVector>();

// List available serial ports
println("Available serial ports:");
for (int i = 0; i < Serial.list().length; i++) {
println(i + ": " + Serial.list()[i]);
}

// Connect to Arduino - CHANGE [0] TO CORRECT PORT NUMBER
try {
myPort = new Serial(this, Serial.list()[0], 9600);
myPort.bufferUntil('\n');
println("Connected to: " + Serial.list()[0]);
} catch (Exception e) {
println("Could not connect to serial port!");
println("Check your Arduino connection and change the port number in line 23");
}
}

void draw() {
// Dark background with fade effect
fill(0, 30);
rect(0, 0, width, height);

// Draw radar grid
drawRadarGrid();

// Draw detected objects
drawObjects();

// Draw sweep line
drawSweepLine();

// Draw information
drawInfo();
}

void drawRadarGrid() {
stroke(0, 255, 0, 100);
strokeWeight(1);
noFill();

// Draw distance circles
for (int i = 1; i <= 4; i++) {
float radius = (maxRadius / 4.0) * i;
arc(centerX, centerY, radius * 2, radius * 2, PI, TWO_PI);
}

// Draw angle lines
for (int a = 0; a <= 180; a += 30) {
float radian = radians(a);
float x = centerX + cos(radian) * maxRadius;
float y = centerY - sin(radian) * maxRadius;
line(centerX, centerY, x, y);
}

// Draw distance labels
fill(0, 255, 0);
textAlign(CENTER);
textSize(12);
for (int i = 1; i <= 4; i++) {
int dist = (200 / 4) * i;
float radius = (maxRadius / 4.0) * i;
text(dist + "cm", centerX, centerY - radius + 5);
}

// Draw angle labels
text("0°", centerX + maxRadius - 20, centerY + 20);
text("90°", centerX, centerY - maxRadius + 20);
text("180°", centerX - maxRadius + 20, centerY + 20);
}

void drawObjects() {
fill(255, 0, 0);
noStroke();

// Draw all detected objects with fading
for (int i = objects.size() - 1; i >= 0; i--) {
PVector obj = objects.get(i);

// Calculate position
float radian = radians(obj.x);
float dist = map(obj.y, 0, 200, 0, maxRadius);
float x = centerX + cos(radian) * dist;
float y = centerY - sin(radian) * dist;

// Draw object with fading
float alpha = map(i, 0, objects.size() - 1, 50, 255);
fill(255, 0, 0, alpha);
ellipse(x, y, 8, 8);
}

// Remove old objects (keep last 50)
while (objects.size() > 50) {
objects.remove(0);
}
}

void drawSweepLine() {
stroke(0, 255, 0);
strokeWeight(2);

float radian = radians(angle);
float x = centerX + cos(radian) * maxRadius;
float y = centerY - sin(radian) * maxRadius;

line(centerX, centerY, x, y);
}

void drawInfo() {
fill(0, 255, 0);
textAlign(LEFT);
textSize(16);

text("ARDUINO RADAR SYSTEM", 20, 30);
text("Angle: " + angle + "°", 20, 55);
text("Distance: " + distance + " cm", 20, 80);
text("Objects: " + objects.size(), 20, 105);

if (myPort != null) {
fill(0, 255, 0);
text("● CONNECTED", 20, 130);
} else {
fill(255, 0, 0);
text("● DISCONNECTED", 20, 130);
}

// Instructions
textSize(12);
text("Press 'c' to clear objects", 20, height - 40);
text("Press 'r' to reconnect", 20, height - 25);
}

void serialEvent(Serial myPort) {
try {
data = myPort.readStringUntil('\n');

if (data != null) {
data = trim(data);

// Parse angle and distance
String[] values = split(data, ',');
if (values.length == 2) {
angle = int(values[0]);
distance = int(values[1]);

// Add object if valid distance
if (distance > 2 && distance < 200) {
objects.add(new PVector(angle, distance));
}

// Debug output
println("Angle: " + angle + "°, Distance: " + distance + "cm");
}
}
} catch (Exception e) {
println("Error reading data: " + e.getMessage());
}
}

void keyPressed() {
if (key == 'c' || key == 'C') {
objects.clear();
println("Objects cleared");
}

if (key == 'r' || key == 'R') {
// Reconnect to serial port
if (myPort != null) {
myPort.stop();
}
try {
myPort = new Serial(this, Serial.list()[0], 9600);
myPort.bufferUntil('\n');
println("Reconnected");
} catch (Exception e) {
println("Reconnection failed");
}
}
}

error

Sketch uses 5682 bytes (2%) of program storage space. Maximum is 253952 bytes.
Global variables use 366 bytes (4%) of dynamic memory, leaving 7826 bytes for local variables. Maximum is 8192 bytes.
avrdude: ser_open(): can't open device "\\.\COM5": The system cannot find the file specified.

avrdude: ser_drain(): read error: The handle is invalid.

avrdude: ser_send(): write error: sorry no info avail
avrdude: stk500_send(): failed to send command to serial port
avrdude: ser_recv(): read error: The handle is invalid.

avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: ser_send(): write error: sorry no info avail
avrdude: stk500_send(): failed to send command to serial port
avrdude: ser_recv(): read error: The handle is invalid.

avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_getsync(): timeout communicating with programmer
Failed uploading: uploading error: exit status 1

Fix

🔧 Fix "Can't Open Device COM5" Error

Step 1: Find Your Arduino's REAL COM Port

Unplug your Arduino from USB completely
In Arduino IDE, go to Tools → Port
Write down all COM ports you see (or take a screenshot)
Plug your Arduino back in and wait 10 seconds
Go to Tools → Port again
Look for a NEW COM port that appeared - this is your Arduino!

Step 2: Windows Device Manager Check

Press Windows Key + X
Click "Device Manager"
Look under "Ports (COM & LPT)"
You should see "Arduino Mega 2560 (COMx)" or similar
Note the COM number - this is your real port!

If you don't see Arduino in Device Manager:

🔴 Arduino Not Recognized - Driver Fix

Option A: Automatic Driver Install

Unplug Arduino
Download Arduino IDE again from arduino.cc
Install fresh (this includes drivers)
Plug Arduino back in

Option B: Manual Driver Install

Go to Device Manager
Look for "Unknown Device" or "USB Device"
Right-click → Update Driver
Browse to Arduino IDE folder → drivers
Install the Arduino driver

🚀 Quick Solutions to Try Right Now

Solution 1: Try Different COM Ports

In Arduino IDE:

Tools → Port → COM3 (try uploading)
Tools → Port → COM4 (try uploading)
Tools → Port → COM6 (try uploading)
Keep trying until one works!

Solution 2: Reset Everything

Close Arduino IDE completely
Unplug Arduino
Wait 30 seconds
Plug Arduino back in
Open Arduino IDE
Check Tools → Port for available ports

Solution 3: Different USB Port/Cable

Try a different USB port on your computer
Try a different USB cable (some cables are power-only)
Avoid USB hubs - plug directly into computer

🔍 Diagnostic Questions

Tell me:

What COM ports do you see in Tools → Port right now?
Is there anything in Windows Device Manager under "Ports (COM & LPT)"?
Does the Arduino LED light up when you plug it in?
What computer are you using (Windows 10/11)?

💡 Most Likely Quick Fix

The real problem: You're trying to use COM5, but your Arduino is probably on COM3 or COM4.

Try this right now:

Tools → Port
Select COM3 (if available)
Try uploading
If that fails, try COM4, COM6, etc.

🎯 Emergency Solution - Use Different Computer

If nothing works:

Try a different computer (laptop, friend's computer)
This will tell us if it's a driver/software issue or hardware problem

Most of these COM port errors are fixed within 5 minutes once we find the correct port!

What COM ports do you see available in Tools → Port right now?

Radar 4

Simple Arduino Radar with Processing - Step by Step Guide

Why This Approach is Much Easier

Components Needed (Only 3!)

Super Simple Wiring (Only 6 Wires!)

Arduino Mega Pin Connections

Visual Wiring Guide

Step 1: Physical Assembly (15 minutes)

Mount Ultrasonic Sensor to Servo

Make Connections

Step 2: Install Software (10 minutes)

Download Processing

Prepare Arduino IDE

Step 3: Upload Arduino Code (5 minutes)

Test Arduino is Working

Step 4: Run Processing Display (5 minutes)

Fix Serial Port Connection

Step 5: Enjoy Your Working Radar! 🎉

Testing Your Radar

Test Object Detection

Keyboard Controls

Troubleshooting Common Issues

Problem: Arduino Serial Monitor shows no data

Problem: Processing can't connect to serial port

Problem: Servo doesn't move smoothly

Problem: No objects detected

Customization Options

Adjust Scanning Speed

Change Angle Step Size

Modify Detection Range

Change Radar Colors in Processing

Why This Approach is Better for Learning

Next Steps (Advanced)

Comments4

ARDUINO CODE (Upload this to your Arduino Mega first)

🔵 PROCESSING CODE (Run this on your computer after Arduino work

error

Fix

🔧 Fix "Can't Open Device COM5" Error

Step 1: Find Your Arduino's REAL COM Port

Step 2: Windows Device Manager Check

🔴 Arduino Not Recognized - Driver Fix

Option A: Automatic Driver Install

Option B: Manual Driver Install

🚀 Quick Solutions to Try Right Now

Solution 1: Try Different COM Ports

Solution 2: Reset Everything

Solution 3: Different USB Port/Cable

🔍 Diagnostic Questions

💡 Most Likely Quick Fix

🎯 Emergency Solution - Use Different Computer