Arduino Project
Radar Guard 3.0
Course Introduction
In this lesson, we will learn how to use the Ultrasonic Sensor Module, Digital Servo Motor, and MAX7219 Dot Matrix Module with the Arduino Board to create a radar defense system version 3.0.
When the ultrasonic sensor module detects an object, it will display the object’s range on the MAX7219 Dot Matrix Module.
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:
Digital Servo Motor
Connect to breadboard’s positive power bus.
Connect to breadboard’s negative power bus.
Connect to 2 on the Arduino.
Ultrasonic Sensor Module
Trig: Connect to 4 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.
MAX7219 Dot Matrix Module
CLK: Connect to 11 on the Arduino.
CS: Connect to 10 on the Arduino.
DIN: Connect to 12 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 LedControl and install it.
Don’t forget to select the board(Arduino UNO R4 WIFI) and the correct port before clicking the Upload button.
#include
#include
// hardware pins
LedControl lc(12, 11, 10, 4); // DIN=12, CLK=11, CS=10, 4 modules
Servo radarServo;
const int servoPin = 2; // servo control pin
const int trigPin = 4; // HC-SR04 Trig pin
const int echoPin = 3; // HC-SR04 Echo pin
// timing
const unsigned long updateInterval = 20; // ms per step
unsigned long lastUpdate = 0;
int currentAngle = 0;
int increment = 1;
// thresholds for rows 0..7
const int thresholds[8] = { 32, 28, 24, 20, 16, 12, 8, 4 };
void setup() {
Serial.begin(9600);
// init LED matrix
for (int m = 0; m < 4; m++) {
lc.shutdown(m, false);
lc.setIntensity(m, 8);
lc.clearDisplay(m);
}
// init servo
radarServo.attach(servoPin);
radarServo.write(currentAngle);
// init ultrasonic
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
}
void loop() {
unsigned long now = millis();
if (now - lastUpdate < updateInterval) return;
lastUpdate = now;
// 1) move servo to currentAngle
radarServo.write(currentAngle);
// 2) measure distance
float d = getDistance();
Serial.print("Angle: ");
Serial.print(currentAngle);
Serial.print("°, Distance: ");
Serial.print(d);
Serial.println(" cm");
// 3) map angle -> step -> module & col
int step = map(currentAngle, 0, 180, 31, 0);
int module = step / 8;
int col = 7 - (step % 8);
// 4) always light row 0 at (module,col)
lc.setLed(module, 0, col, true);
// then for each deeper threshold light extra rows
for (int r = 1; r < 8; r++) {
if (d <= thresholds[r]) {
lc.setLed(module, r, col, true);
}
}
// 5) update angle
currentAngle += increment;
// 6) at each end clear all before reversing
if (currentAngle >= 180) {
currentAngle = 180;
increment = -1;
clearAll();
} else if (currentAngle <= 0) {
currentAngle = 0;
increment = 1;
clearAll();
}
}
// perform ultrasonic distance measurement (cm)
float getDistance() {
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
long dur = pulseIn(echoPin, HIGH, 30000);
return dur * 0.034 / 2;
}
// helper: clear entire display
void clearAll() {
for (int m = 0; m < 4; m++) {
lc.clearDisplay(m);
}
}