Circular LED Clock with Proximity Sensor Display using Arduino & NeoPixels

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If you love creative electronics projects, this Circular LED Clock with Proximity Sensor Display is a perfect DIY project. Using 60 NeoPixel LEDs arranged in a ring, this smart clock visually represents hours, minutes, and seconds using different colors. The project also integrates an HC-SR04 ultrasonic sensor, allowing users to change the clock display mode simply by waving their hand near the sensor.

This project is ideal for Arduino enthusiasts, robotics students, and IoT beginners who want to build a visually appealing and interactive digital clock.

Why Build a Circular LED Clock?

Traditional clocks use mechanical hands, but modern electronics allow us to create dynamic LED clocks with interactive features. This project demonstrates how addressable LEDs and sensors can be combined to build a futuristic display.


Key Benefits

  • Interactive gesture control

  • Attractive LED visualization

  • Hands-free display mode switching

  • Great learning project for Arduino programming

Components Required

To build the Circular LED Clock with Proximity Sensor, you will need the following components:

  • Arduino Uno / Nano

  • 60 LED NeoPixel Ring (WS2812B)

  • HC-SR04 Ultrasonic Sensor

  • Real Time Clock (RTC) Module (DS3231 recommended)

  • Breadboard

  • Jumper wires

  • 5V Power Supply

  • 330Ω resistor

  • 1000µF capacitor (recommended for NeoPixels)

Diagram.json:
{
  "version": 1,
  "author": "NeoPixel Clock",
  "editor": "wokwi",
  "parts": [
    {
      "type": "wokwi-arduino-mega",
      "id": "mega",
      "top": 200,
      "left": 100,
      "attrs": {}
    },
    {
      "type": "wokwi-led-ring",
      "id": "ring1",
      "top": -180,
      "left": -180,
      "attrs": { "pixels": "60" }
    },
    {
      "type": "wokwi-hc-sr04",
      "id": "sonar1",
      "top": 450,
      "left": 250,
      "attrs": { "distance": "25" }
    },
    {
      "type": "wokwi-pushbutton",
      "id": "btnA",
      "top": 450,
      "left": 50,
      "attrs": { "color": "blue" }
    },
    {
      "type": "wokwi-pushbutton",
      "id": "btnB",
      "top": 450,
      "left": 130,
      "attrs": { "color": "green" }
    }
  ],
  "connections": [
    ["ring1:GND",    "mega:GND.1",   "black",  []],
    ["ring1:VCC",    "mega:5V",      "red",    []],
    ["ring1:DIN",    "mega:6",       "green",  []],

    ["sonar1:GND",   "mega:GND.2",   "black",  []],
    ["sonar1:VCC",   "mega:5V",      "red",    []],
    ["sonar1:TRIG",  "mega:10",      "orange", []],
    ["sonar1:ECHO",  "mega:11",      "yellow", []],

    ["btnA:1.l",     "mega:2",       "blue",   []],
    ["btnA:2.l",     "mega:GND.3",   "black",  []],

    ["btnB:1.l",     "mega:3",       "green",  []],
    ["btnB:2.l",     "mega:GND.4",   "black",  []]
  ]
}

How the Circular LED Clock Works

The clock uses 60 NeoPixels arranged in a circular ring, representing the 60 seconds or minutes in a clock face.

Each LED represents a position on the clock:

  • 🔴 Red LED → Hour indicator

  • 🔵 Blue LED → Minute indicator

  • 🟢 Green LED → Second indicator

The RTC module keeps accurate time, while the Arduino reads the current time and lights up the LEDs accordingly.

Code:

// =====================================================
//  NEOPIXEL RING CLOCK — Wokwi Arduino MEGA
//  Part:    wokwi-led-ring  (pixels=60)
//  Library: Adafruit NeoPixel
//  Pins:    DIN→6, TRIG→10, ECHO→11, BTN_A→2, BTN_B→3
// =====================================================
#include <Adafruit_NeoPixel.h>

#define LED_PIN    6
#define NUM_LEDS   60
#define TRIG_PIN   10
#define ECHO_PIN   11
#define BTN_A      2
#define BTN_B      3

Adafruit_NeoPixel ring(NUM_LEDS, LED_PIN, NEO_GRB + NEO_KHZ800);

int hh = 10, mm = 9, sc = 0;   // sc instead of SS (SS is reserved by SPI)
unsigned long prevMs = 0;
uint8_t dispMode = 0;
bool prevA = HIGH, prevB = HIGH;
unsigned long dbA = 0, dbB = 0;

// --- ultrasonic ---
long ping() {
  digitalWrite(TRIG_PIN, LOW);  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH); delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  long t = pulseIn(ECHO_PIN, HIGH, 23000);
  return t ? t * 17L / 1000 : 60;
}

// --- colour wheel 0-255 ---
uint32_t wheel(uint8_t p) {
  p = 255 - p;
  if (p < 85)  return ring.Color(255-p*3, 0,       p*3);
  if (p < 170) { p -= 85;  return ring.Color(0,     p*3, 255-p*3); }
                 p -= 170; return ring.Color(p*3, 255-p*3, 0);
}

uint32_t scalec(uint32_t c, uint8_t f) {
  return ring.Color(
    ((c>>16)&0xFF)*f/255,
    ((c>> 8)&0xFF)*f/255,
    ( c     &0xFF)*f/255);
}

// ---- MODE 0 : Clock ----
void modeClock() {
  ring.clear();
  for (int i = 0; i < 60; i += 5)
    ring.setPixelColor(i, ring.Color(14, 14, 14));

  // hour (red)
  int hc = (int)round(((hh%12)*60.0f + mm) / 720.0f * 60.0f) % 60;
  for (int d = -2; d <= 2; d++) {
    int px = (hc+d+60)%60;
    uint8_t b = (d==0)?230:(abs(d)==1?100:35);
    uint32_t old = ring.getPixelColor(px);
    ring.setPixelColor(px, ring.Color(min(255,(int)((old>>16)&0xFF)+b),(old>>8)&0xFF,old&0xFF));
  }
  // minute (green)
  int mc = (int)round((mm*60.0f+sc)/3600.0f*60.0f) % 60;
  ring.setPixelColor((mc-1+60)%60, scalec(ring.Color(0,255,80),70));
  ring.setPixelColor(mc,            ring.Color(0,255,80));
  ring.setPixelColor((mc+1)%60,    scalec(ring.Color(0,255,80),70));
  // second (cyan)
  ring.setPixelColor(sc%60, ring.Color(0,210,255));
  ring.show();
}

// ---- MODE 1 : Equalizer ----
uint8_t eqH[8] = {20,42,16,52,34,28,46,22};
int8_t  eqV[8] = { 1,-1, 1,-1, 1,-1, 1,-1};
unsigned long eqMs = 0;

void modeEQ() {
  if (millis()-eqMs > 65) {
    for (int i=0;i<8;i++) {
      eqH[i] += eqV[i]*(int8_t)random(2,7);
      if (eqH[i]>=58||eqH[i]<=4){eqV[i]=-eqV[i];eqH[i]=constrain(eqH[i],4,58);}
    }
    eqMs = millis();
  }
  ring.clear();
  for (int b=0;b<8;b++) {
    int ctr = b*7+3;
    uint8_t br = map(eqH[b],4,58,40,255);
    uint32_t c = wheel(map(eqH[b],4,58,0,185));
    for (int d=-2;d<=2;d++) {
      int px = (ctr+d+60)%60;
      uint8_t f = (d==0)?255:(abs(d)==1?130:45);
      ring.setPixelColor(px, scalec(c,(uint16_t)br*f/255));
    }
  }
  ring.show();
}

// ---- MODE 2 : Radar ----
int radarHead = 0;
unsigned long radarMs = 0;

void modeRadar() {
  if (millis()-radarMs > 22){radarHead=(radarHead+1)%60; radarMs=millis();}
  ring.clear();
  for (int i=0;i<18;i++){
    int px=(radarHead-i+60)%60;
    ring.setPixelColor(px, ring.Color(0, map(i,0,17,210,4), 0));
  }
  long cm = ping();
  if (cm < 40){
    int obj = map(cm,2,40,0,59);
    ring.setPixelColor(obj,            ring.Color(255,80,0));
    ring.setPixelColor((obj+1)%60,     ring.Color(80,20,0));
    ring.setPixelColor((obj-1+60)%60,  ring.Color(80,20,0));
  }
  ring.show();
}

// ---- MODE 3 : Rainbow ----
uint16_t rbPos = 0;
unsigned long rbMs = 0;

void modeRainbow() {
  long cm = constrain(ping(),2,40);
  uint8_t spd = map(cm,2,40,14,1);
  if (millis()-rbMs > spd){rbPos=(rbPos+1)%256; rbMs=millis();}
  for (int i=0;i<NUM_LEDS;i++) ring.setPixelColor(i, wheel((i*4+rbPos)&0xFF));
  ring.show();
}

// ---- buttons ----
void checkButtons() {
  unsigned long now = millis();
  bool a = digitalRead(BTN_A);
  bool b = digitalRead(BTN_B);
  if (prevA==HIGH && a==LOW && now-dbA>200){
    dispMode=(dispMode+1)%4; dbA=now;
    ring.fill(ring.Color(25,25,25)); ring.show(); delay(55); ring.clear();
  }
  if (prevB==HIGH && b==LOW && now-dbB>200){
    mm=(mm+5)%60; sc=0; dbB=now;
  }
  prevA=a; prevB=b;
}

void setup() {
  ring.begin();
  ring.setBrightness(75);
  ring.show();
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(BTN_A, INPUT_PULLUP);
  pinMode(BTN_B, INPUT_PULLUP);
  // boot spiral
  for (int i=0;i<NUM_LEDS;i++){ring.setPixelColor(i,wheel(i*4));ring.show();delay(16);}
  delay(250);
  for (int i=NUM_LEDS-1;i>=0;i--){ring.setPixelColor(i,0);ring.show();delay(9);}
  prevMs = millis();
  randomSeed(42);
}

void loop() {
  checkButtons();
  if (millis()-prevMs >= 1000){
    prevMs += 1000;
    if(++sc >= 60){ sc=0; if(++mm >= 60){ mm=0; if(++hh >= 24) hh=0; }}
  }
  switch(dispMode){
    case 0: modeClock();   break;
    case 1: modeEQ();      break;
    case 2: modeRadar();   break;
    case 3: modeRainbow(); break;
  }
  delay(8);
}


Gesture Control with Ultrasonic Sensor

The HC-SR04 ultrasonic sensor detects hand movement in front of the clock.

When you wave your hand near the sensor, the display mode changes.

Display Modes

Mode 1 – Classic Clock Mode

  • Hour, minute, and second LEDs displayed simultaneously.

Mode 2 – Minimal Mode

  • Only hour and minute LEDs displayed.

Mode 3 – Seconds Animation

  • LEDs animate like a rotating second hand.

Mode 4 – Rainbow LED Mode

  • Entire ring glows with animated color patterns.

This feature makes the clock touchless and interactive, giving it a futuristic feel.

Circuit Connections

NeoPixel Ring

  • VCC → 5V

  • GND → GND

  • Data → Arduino Pin 6

Ultrasonic Sensor

  • VCC → 5V

  • GND → GND

  • TRIG → Arduino Pin 9

  • ECHO → Arduino Pin 10

RTC Module

  • VCC → 5V

  • GND → GND

  • SDA → A4

  • SCL → A5


Arduino Code Overview

The Arduino program performs three main tasks:

  1. Reads current time from the RTC module

  2. Controls the NeoPixel LEDs to represent clock hands

  3. Uses the ultrasonic sensor to detect gestures and change modes

Libraries typically used:

  • Adafruit NeoPixel Library

  • RTClib Library

These libraries simplify LED control and time reading.

Applications of LED Clock Project

This project is not just a decorative gadget but also a great educational tool.

Possible uses include:

  • Robotics and electronics learning projects

  • STEM classroom demonstrations

  • Smart home décor

  • Arduino programming practice

  • Interactive IoT prototype

Tips for Better Performance

  • Use an external 5V power supply for the NeoPixel ring.

  • Add a 1000µF capacitor across power lines to protect LEDs.

  • Use a DS3231 RTC module for accurate timekeeping.

  • Keep the ultrasonic sensor unobstructed for better gesture detection.



Final Thoughts

The Circular LED Clock with Proximity Sensor Display combines LED visualization, sensors, and Arduino programming to create an innovative interactive clock. With gesture control and colorful NeoPixel animations, this project is both educational and visually impressive.

If you enjoy Arduino, IoT, and robotics projects, this DIY LED clock is a fantastic addition to your project collection.

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