ESP8266 Pinouts: ESP-01/01S, NodeMCU & D1 Mini GPIO Guide

This guide explains the most common ESP8266AliExpress price variants (ESP-01AliExpress price, ESP-12E/F, NodeMCUAliExpress price and D1 mini) and shows their pinouts, safe GPIOs, and boot-sensitive pins to avoid.

The ESP8266AliExpress price started life as a tiny Wi-Fi module but quickly became a full microcontroller platform. Under the metal cans, almost all modules use the same chip (ESP8266EX) – what changes is:

• How many GPIO pins are brought out
• Antenna type (PCB vs ceramic vs u.FL)
• Form factor (bare module vs dev board)

Quick verdict: choose a D1 Mini for the smallest general-purpose development board, NodeMCUAliExpress price when easy USB setup and more breadboard space matter, an ESP-12F for custom PCBs, and an ESP-01S only when two boot-sensitive GPIOs are enough.

1. ESP-01 / ESP-01S – 8-pin “stick” module
2. ESP-12E / ESP-12F (and ESP-07) – 22-pad SMD modules
3. NodeMCU dev board – ESP-12E on a USB dev board
4. Wemos D1 mini – small, breadboard-friendly dev board

And we’ll summarise pinouts and which pins are “safe” to use.

⚠️ ESP8266 GPIOs use 3.3 V logic. Feeding 5 V directly into a GPIO can damage the chip.

ESP-01 and ESP-01S Pinout

The ESP-01 is the original “blue board” most people saw first: a tiny module with only 8 pins broken out. It’s cheap and widely used in legacy designs.

Typical pinout (viewed from top, pins pointing down)

Pin	Name	Function
1	GND	Ground
2	GPIO2	I/O, also affects boot mode
3	GPIO0	I/O, boot-mode / flash pin
4	RXD0	UART0 RX
5	TXD0	UART0 TX
6	CH_PD / EN	Chip enable (pull HIGH to run)
7	RST	Reset (active LOW)
8	VCC	3.3 V power

Practical notes:

• Usable GPIOs in normal projects: GPIO0, GPIO2 (both have boot-mode roles)
• To flash firmware, you usually:
  • Hold GPIO0 LOW at reset → enter bootloader
  • Use TXD0/RXD0 as serial connection
• Very limited number of I/O pins makes ESP-01 a pain for bigger projects. Great as a Wi-Fi modem or for very small nodes.

ESP-12E, ESP-12F and ESP-07 Pinouts

Modules like ESP-12E, ESP-12F and ESP-07 expose almost all usable pins of the ESP8266EX. They’re metal-shielded SMD modules used on dev boards like NodeMCU.

They all share a very similar core pinout; ESP-12E/F adds an extra bottom row mainly for flash pins.

High-level features of the ESP-12 class:

• 17 GPIOs total on the chip, ~11–13 usable on typical modules
• 1× 10-bit ADC (A0)
• PCB antenna (ESP-12), ceramic antenna (ESP-07)

Typical ESP-12E pin groups:

• Power & control: VCC, GND, EN/CH_PD, RST
• UART0: TXD0 (GPIO1), RXD0 (GPIO3) – default programming / logging port
• SPI flash pins: GPIO6–GPIO11 – used internally, don’t touch
• General GPIOs: GPIO0, 2, 4, 5, 12, 13, 14, 15, 16
• ADC: TOUT or ADC0 – 0–1.0 V max

Example bare ESP-12E pinout:

• “Safe” GPIOs most people use:
  • GPIO4, GPIO5, GPIO12, GPIO13, GPIO14 → best general I/O
  • GPIO16 can wake the ESP8266 from deep sleep only when it is wired to RST.
• Boot-sensitive pins:
  • GPIO0, GPIO2, GPIO15 control boot mode – must be at the right level on reset.
  • GPIO1/3 used for UART – toggled during boot.

NodeMCU ESP8266 Pinout

NodeMCU boards like NodeMCU v1.0 (ESP-12E) take an ESP-12 module and add:

• USB-to-serial (CP2102/CH340)
• 3.3 V regulator
• Auto-reset / auto-flash circuitry
• Breadboard-friendly pins labelled D0, D1, D2… instead of raw GPIO numbers

Typical NodeMCU ESP-12E dev board pinout:

Board label	ESP8266 GPIO	Notes
D0	GPIO16	No PWM; wire D0 to RST for deep-sleep wake
D1	GPIO5	I²C SCL (by convention)
D2	GPIO4	I²C SDA (by convention)
D3	GPIO0	Boot mode pin, pulled-up
D4	GPIO2	Boot mode pin, on-board LED on many
D5	GPIO14	HSPI CLK
D6	GPIO12	HSPI MISO
D7	GPIO13	HSPI MOSI
D8	GPIO15	Boot mode pin, pulled-down
RX	GPIO3	UART0 RX (Serial)
TX	GPIO1	UART0 TX (Serial)
A0	ADC0	Board-dependent divider; commonly about 3.2–3.3 V max. Bare ESP8266 TOUT is 1.0 V max.

Good defaults on NodeMCU:

• I²C → D2 (GPIO4) SDA, D1 (GPIO5) SCL
• SPI → D5 (GPIO14) SCK, D6 (GPIO12) MISO, D7 (GPIO13) MOSI, D8 (GPIO15) CS
• Avoid using D3 (GPIO0), D4 (GPIO2), D8 (GPIO15) for things that pull hard HIGH/LOW at boot.

Wemos/LOLIN D1 Mini Pinout

The Wemos D1 mini is a very compact dev board with an ESP-12 module, micro-USB and 3.3 V regulator. It exposes 11 usable GPIOs and is extremely popular in DIY and Home Assistant projects.

Typical D1 mini pin mapping:

Label	GPIO	Typical use
D0	GPIO16	Wire D0 to RST for deep-sleep wake; no PWM
D1	GPIO5	I²C SCL
D2	GPIO4	I²C SDA
D3	GPIO0	Boot pin, input w/PU
D4	GPIO2	Boot pin, on-board LED
D5	GPIO14	SPI SCK
D6	GPIO12	SPI MISO
D7	GPIO13	SPI MOSI
D8	GPIO15	Boot pin (pulled-down)
RX	GPIO3	UART0 RX
TX	GPIO1	UART0 TX
A0	ADC0	3.2 V max on the official D1 Mini

Notes:

• Only one ADC channel (A0).
• D0 (GPIO16) lacks the usual interrupt, PWM, I²C and OneWire support; wire D0 to RST for deep-sleep wake.
• Don’t tie D3, D4, D8 to random stuff that changes the boot levels.

Other ESP8266 Module Variants

There are more SMD modules, but they’re all the same chip plus different antennas / footprints:

• ESP-05 – tiny module with just UART pins and power (like ESP-01 but even more limited).
• ESP-07 – similar pinout to ESP-12 but with ceramic antenna and u.FL connector.
• ESP-201 / ESP-14 – older / less common modules with their own pinouts.

The main differences are:

• How many GPIOs are broken out
• Antenna type (PCB vs ceramic vs external connector)
• Footprint and shield size

The actual SoC (ESP8266EX) and its GPIO roles are the same across all of them.

Safe GPIOs and Boot Pins

Because of boot-mode strapping, some pins must be at defined levels during reset. The classic rule from the ESP8266 pinout references:

Boot strapping pins:

• GPIO0
• GPIO2
• GPIO15

Valid boot from flash requires:

• GPIO0 = HIGH
• GPIO2 = HIGH
• GPIO15 = LOW

So:

• Don’t pull GPIO0 or GPIO2 hard LOW at boot.
• Don’t pull GPIO15 HIGH at boot.
• You can use them after boot, but avoid big loads or things that force the wrong level during reset.

Generally safe GPIOs on ESP-12 / NodeMCU / D1 mini:

GPIO4, GPIO5, GPIO12, GPIO13, GPIO14, GPIO16