How to Build an ESP32 Desk Presence Busy Light

Motion sensing, manual busy mode, OLED status, and a colour LED ring

ESP32 Smart Home Beginner35 minutes4 components

Updated May 27, 2026

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How to Build an ESP32 Desk Presence Busy Light — For illustrative purposes only

On this page

What you'll build
Wiring diagram
Components needed
Assembly
Pin assignments
Code

What you'll build

This guide walks you through building a small ESP32 desk presence light that makes your workspace status obvious at a glance. A PIR motion sensor marks the desk as recently active, a tactile button toggles manual busy mode, an SSD1306 OLED shows the current state in plain text, and a WS2812B LED ring changes colour: green for free, orange for recently active, and red when you have deliberately set focus mode.

The build is intentionally practical rather than flashy. You will wire a common PIR module to a digital input, use the ESP32 internal pull-up for the button, share the OLED over I2C, and drive the addressable LED ring from one data pin. The firmware keeps the motion state alive for a short window after movement, debounces the button, and updates both the display and lights without needing Wi-Fi, accounts, or a phone app.

By the end you will have a useful desk sign for shared studios, home offices, livestream setups, or classrooms where people need a simple signal before interrupting you. The code is easy to adapt: change the timeout, swap the LED colours, add a quiet mode for evenings, or send the state over MQTT later once the physical version works reliably.

Wiring diagram

React Flow

Components needed

Component	Type	Qty	Buy
HC-SR501 PIR Motion Sensor	sensor	1	€1.85
Tactile Push Button	input	1	€8.30
WS2812B LED Ring	actuator	1
SSD1306 OLED Display	display	1	€4.30

Prices and availability are indicative and may have been updated by the supplier. Schematik may earn a commission from purchases made through affiliate links.

Assembly

Wire the shared power rails

Connect each module VCC to the ESP32 3V3 rail where supported, and connect all grounds together.

Connect the PIR sensor

Wire PIR OUT to GPIO 27, then place the sensor so it sees the desk rather than the whole room.

Add the busy button

Connect the button signal side to GPIO 26 and the other side to ground. The firmware uses the internal pull-up.

Connect the LED ring and OLED

Wire the LED ring DIN to GPIO 4. Connect the OLED SDA to GPIO 21 and SCL to GPIO 22.

Upload and tune

Upload the sketch, check the three states, then adjust occupiedHoldMs if the status clears too quickly or too slowly.

Pin assignments

Pin	Connection	Type
3V3	pir-1 VCC	POWER
GND	pir-1 GND	GROUND
GPIO 27	pir-1 OUT	DIGITAL
GPIO 26	button-1 SIG	DIGITAL
GND	button-1 GND	GROUND
3V3	led-ring-1 VCC	POWER
GND	led-ring-1 GND	GROUND
GPIO 4	led-ring-1 DIN	DIGITAL
3V3	oled-1 VCC	POWER
GND	oled-1 GND	GROUND
GPIO 21	oled-1 SDA	I2C
GPIO 22	oled-1 SCL	I2C

Code

Arduino C++

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#include <Wire.h>
#include <Adafruit_SSD1306.h>
#include <Adafruit_GFX.h>
#include <FastLED.h>

#define PIR_PIN 27
#define BUTTON_PIN 26
#define LED_PIN 4
#define NUM_LEDS 12
#define SDA_PIN 21
#define SCL_PIN 22

Adafruit_SSD1306 display(128, 64, &Wire, -1);
CRGB leds[NUM_LEDS];

bool manualBusy = false;
bool occupied = false;
unsigned long lastMotionMs = 0;
unsigned long lastButtonMs = 0;
const unsigned long occupiedHoldMs = 120000;

void setRing(CRGB color) {
  fill_solid(leds, NUM_LEDS, color);
  FastLED.show();
}

void drawStatus(const char* status, const char* detail) {
  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);
  display.setTextSize(2);
  display.setCursor(0, 6);
  display.println(status);
  display.setTextSize(1);
  display.setCursor(0, 40);
  display.println(detail);
  display.display();
}

void setup() {
  pinMode(PIR_PIN, INPUT);
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  Wire.begin(SDA_PIN, SCL_PIN);
  FastLED.addLeds<NEOPIXEL, LED_PIN>(leds, NUM_LEDS);
  FastLED.setBrightness(80);
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  drawStatus("FREE", "Wave nearby or press button");
  setRing(CRGB::Green);
}

void loop() {
  if (digitalRead(PIR_PIN) == HIGH) {
    occupied = true;
    lastMotionMs = millis();
  }

  if (digitalRead(BUTTON_PIN) == LOW && millis() - lastButtonMs > 350) {
    manualBusy = !manualBusy;
    lastButtonMs = millis();
  }

  if (occupied && millis() - lastMotionMs > occupiedHoldMs) {
    occupied = false;
  }

  if (manualBusy) {
    setRing(CRGB::Red);
    drawStatus("BUSY", "Manual focus mode");
  } else if (occupied) {
    setRing(CRGB::Orange);
    drawStatus("HERE", "Motion seen at desk");
  } else {
    setRing(CRGB::Green);
    drawStatus("FREE", "No recent motion");
  }

  delay(200);
}

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