Arduino Project
Distance Display 1.0
Course Introduction
In this project, we use an ultrasonic sensor and three groups of LEDs (green, yellow, red) to simulate a radar-style proximity alert system with the Arduino board.
The system measures the distance to an object and activates different LED groups based on how close the object is: green LEDs indicate a safe distance (≤15 cm), yellow LEDs warn that the object is getting closer (≤10 cm), and red LEDs signal a critical proximity alert (≤5 cm). The LEDs turn on from left to right and turn off from right to left to enhance the visual effect.
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
Wiring
Common Connections:
LED
Connect the LEDs cathode to the negative power bus on the breadboard, and the LEDs anode to a 1kΩ resistor then to 4 ~ 12 on the Arduino.
Ultrasonic Sensor Module
Trig: Connect to 3 on the Arduino.
Echo: Connect to 2 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.
Don’t forget to select the board(Arduino UNO R4 WIFI) and the correct port before clicking the Upload button.
const int echoPin = 2; // Echo pin of the ultrasonic sensor
const int trigPin = 3; // Trig pin of the ultrasonic sensor
// Three LED groups from left to right
const int greenLEDs[] = {12, 11, 10}; // Green LEDs = safe distance
const int yellowLEDs[] = {9, 8, 7}; // Yellow LEDs = getting closer
const int redLEDs[] = {6, 5, 4}; // Red LEDs = very close
// Flags to track if each LED group is on
bool greenOn = false;
bool yellowOn = false;
bool redOn = false;
void setup() {
Serial.begin(9600); // Start the serial monitor
pinMode(echoPin, INPUT); // Set echo pin as input
pinMode(trigPin, OUTPUT); // Set trig pin as output
// Set all LED pins as output
for (int i = 0; i < 3; i++) {
pinMode(greenLEDs[i], OUTPUT);
pinMode(yellowLEDs[i], OUTPUT);
pinMode(redLEDs[i], OUTPUT);
}
Serial.println("Ultrasonic sensor:");
}
void loop() {
float distance = readSensorData(); // Read distance in cm
Serial.print(distance);
Serial.println(" cm");
if (distance <= 15) {
// 15 cm or less: turn on green LEDs
if (!greenOn) {
turnOnLEDs(greenLEDs);
greenOn = true;
}
if (distance <= 10) {
// 10 cm or less: turn on yellow LEDs
if (!yellowOn) {
turnOnLEDs(yellowLEDs);
yellowOn = true;
}
if (distance <= 5) {
// 5 cm or less: turn on red LEDs
if (!redOn) {
turnOnLEDs(redLEDs);
redOn = true;
}
} else {
// More than 5 cm: turn off red LEDs
if (redOn) {
turnOffLEDsReverse(redLEDs);
redOn = false;
}
}
} else {
// More than 10 cm: turn off yellow LEDs
if (yellowOn) {
turnOffLEDsReverse(yellowLEDs);
yellowOn = false;
}
}
} else {
// More than 15 cm: turn off all LEDs
if (redOn) {
turnOffLEDsReverse(redLEDs);
redOn = false;
}
if (yellowOn) {
turnOffLEDsReverse(yellowLEDs);
yellowOn = false;
}
if (greenOn) {
turnOffLEDsReverse(greenLEDs);
greenOn = false;
}
}
delay(50); // Short delay to avoid reading too frequently
}
// Measure distance using ultrasonic sensor
float readSensorData() {
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
float duration = pulseIn(echoPin, HIGH);
return duration / 58.0; // Convert time to distance in cm
}
// Turn on LEDs from left to right
void turnOnLEDs(const int ledArray[]) {
for (int i = 0; i < 3; i++) {
if (digitalRead(ledArray[i]) == LOW) {
digitalWrite(ledArray[i], HIGH);
delay(60); // Add delay for visual effect
}
}
}
// Turn off LEDs from right to left
void turnOffLEDsReverse(const int ledArray[]) {
for (int i = 2; i >= 0; i--) {
if (digitalRead(ledArray[i]) == HIGH) {
digitalWrite(ledArray[i], LOW);
delay(60); // Add delay for visual effect
}
}
}