ESP8266-01 Pinout

Overview

The ESP8266-01 is the smallest, cheapest way to add Wi-Fi to a project: an 8-pin module with just the chip, its antenna and flash. Unlike NodeMCU-style boards, there’s no onboard USB-to-serial chip or 3.3V regulator here, you supply both yourself, and only GPIO0 and GPIO2 are actually usable as general-purpose pins.

No Bluetooth badge here on purpose: the ESP8266 has no Bluetooth radio at all.

Getting started

You’ll need a USB-to-serial adapter set to 3.3V logic (a 5V adapter can damage this module), plus a way to pull GPIO0 low for flashing, most people just use a jumper wire and a breadboard.

Hello World: blink an LED

The microcontroller equivalent of “Hello World”: GPIO2 toggles once a second. Wire an LED (with a resistor) to GPIO2, one of only two general-purpose pins on this module.

#define LED_PIN 2

void setup() {
  pinMode(LED_PIN, OUTPUT);
}

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

Select “Generic ESP8266 Module” first, see “Getting started” above.

Pinout diagram

All 8 pins on the ESP8266-01 module.

Dimensions

The bare ESP8266-01 module: PCB antenna at one end, 2×4-pin header at 2.54 mm pitch at the other.

Pin reference

Boot modes

GPIO0 and GPIO2 together decide how the module starts up.

Safety notes