ESP8266 7-Segment Counter

3631AS 1-digit 7-segment display counter (0-9) with ESP8266 — cycles every 1 second

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What It Does

Counts from 0 to 9 on a single 3631AS 7-segment display, changing every 1 second.
Uses a lookup table to drive segments A-G through GPIO pins with 1kΩ current-limiting resistors.

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Hardware

Component	Model	Qty	Notes
Microcontroller	NodeMCU ESP8266 (ESP-12E)	1
7-Segment Display	3631AS (Common Cathode)	1	1-digit, 10-pin
Resistor	1kΩ	7	Current limiting for segments A-G
Jumper wires	M-M	15

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Pin Mapping

Display Pin	Segment	ESP8266 Pin	GPIO	Connection
10	A	D1	GPIO5	Via 1kΩ resistor
6	B	D3	GPIO0	Via 1kΩ resistor
4	C	D5	GPIO14	Via 1kΩ resistor
2	D	D6	GPIO12	Via 1kΩ resistor
1	E	D7	GPIO13	Via 1kΩ resistor
9	F	D0	GPIO16	Via 1kΩ resistor
5	G	D8	GPIO15	Via 1kΩ resistor
7	DIG3 (GND)	GND	—	Direct jumper wire

Common Cathode: DIG3 pin connects directly to GND. Segments light when GPIO goes HIGH.

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Visual Guide

Breadboard Overview

Display Close-up

Demo

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Wiring Diagram

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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 display should start counting 0→9 immediately

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How It Works

// Lookup table: 1 = segment ON, 0 = segment OFF
const byte numPatterns[10][7] = {
  {1,1,1,1,1,1,0}, // 0
  {0,1,1,0,0,0,0}, // 1
  {1,1,0,1,1,0,1}, // 2
  // ... etc
};

void printNumber(int number) {
  digitalWrite(segA, numPatterns[number][0]);
  // ... drives all 7 segments
}

• Period: 1 second per digit
• Cycle: 0→9 takes 10 seconds, then repeats

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Files

File	Description
src/main.cpp	Main source code
platformio.ini	PlatformIO build configuration
images/	Project photos and demo GIF
schematic/	Wiring diagram

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License

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