ESP8266 Pinout

Overview

This guide covers the ESP8266 as it appears on NodeMCU and Wemos D1 Mini style development boards, the way almost everyone actually encounters this chip. The bare chip and its ESP-12E/F module have far more pins internally, but these boards only break out the ones listed below, add USB, voltage regulation, and reset/flash buttons for easy prototyping.

No Bluetooth badge here on purpose: the ESP8266 has no Bluetooth radio at all, Wi-Fi is the only wireless feature on this chip.

Getting started

Most ESP8266 dev boards use a CH340 or CP2102 USB-to-serial chip, install its driver first if your board doesn’t show up as a serial port.

Hello World: blink an LED

The microcontroller equivalent of “Hello World”: GPIO2 (D4) toggles once a second. Most NodeMCU and Wemos D1 Mini boards already have an onboard LED here, wired active-low, so LOW turns it on.

#define LED_PIN 2 // D4, onboard LED on most boards, active low
void setup() {
  pinMode(LED_PIN, OUTPUT);
}

void loop() {
  digitalWrite(LED_PIN, LOW);  // on  delay(1000);
  digitalWrite(LED_PIN, HIGH); // off  delay(1000);
}

Select your exact board first, see “Getting started” above. There’s no ESP-IDF example here, ESP-IDF targets the newer ESP32 family, not the ESP8266.

Specifications

Official specifications for the ESP8266 chip.

Pinout diagram

The ESP8266 module’s full pin matrix, including the alternate SPI/JTAG/UART functions not broken out on most dev boards.

GPIO quick reference

Board labels (D0–D8) are what’s silkscreened on NodeMCU/Wemos boards, they don’t match the underlying GPIO numbers.

Flashing pins (UART0)

Used by a USB-to-serial adapter (or the onboard one) to upload firmware.

Safety notes