ESP8266 Onboard LED Blink

Practice project: 5Hz onboard LED blinker to learn proper GitHub repo structure for future ESP8266 projects.

What It Does

Blinks the onboard blue LED on a NodeMCU ESP8266 at 5Hz (100ms on, 100ms off).

Originally started as 10Hz (50ms delay), changed to 5Hz in commit a25d380 for better visibility.

This project serves as a template for organizing hardware projects with code, photos, and documentation.

Hardware

Component Model Qty Notes
Microcontroller NodeMCU ESP8266 (ESP-12E) 1 Onboard LED on GPIO2 (D4)
USB Cable Micro-USB 1 Power + programming

Pin Mapping

ESP8266 Pin Connected To Function
GPIO2 (D4) Onboard LED Blink indicator (Active-Low)

Active-Low: LOW = LED ON, HIGH = LED OFF

Visual Guide

Board Overview

Board top view

LED Close-up

LED blinking

Side View

Board side angle

Schematic

This project uses only the onboard LED — no external wiring required.

ESP8266 NodeMCU
┌─────────────┐
│         LED │◄── GPIO2 (D4)
│    [====]   │     (Active-Low)
│             │
│  USB        │
└─────────────┘

Software

PlatformIO Configuration

Setting Value
Platform espressif8266
Board nodemcuv2
Framework arduino

See platformio.ini for full configuration.

Build & Upload

  1. Open project in VS Code with PlatformIO extension
  2. Click Build (checkmark icon) or press Ctrl+Alt+B
  3. Click Upload (arrow icon) or press Ctrl+Alt+U
  4. The onboard blue LED should start blinking immediately

How It Works

digitalWrite(LED_BUILTIN, LOW);   // LED ON  (Active-Low)
delay(100);                       // 100ms
digitalWrite(LED_BUILTIN, HIGH);  // LED OFF
delay(100);                       // 100ms
// Cycle repeats → 5Hz blink

Frequency Note

Files

File Description
src/main.cpp Main source code
platformio.ini PlatformIO build configuration
images/ Project photos
schematic/ Wiring diagrams (N/A for this project)

License

MIT — Use this as a template for your own projects.