ESP8266 Wi-Fi Serial Transceiver Module
General-purpose ESP8266 breakout with more accessible GPIO.
A more fully-broken-out ESP8266 module than the ESP-01, exposing extra GPIO pins alongside its Wi-Fi radio. It packages the same ESP8266 Wi-Fi SoC used across the ESP-01 through ESP-12 family, but on a board layout that surfaces more of the chip's usable GPIO, ADC, and control pins, making it easier to wire directly into a breadboard project without the limited 2-GPIO constraint of the ESP-01.
Specifications
| Wi-Fi chipset | ESP8266 SoC, 802.11 b/g/n 2.4GHz Wi-Fi |
| CPU | Tensilica L106 32-bit RISC, up to 80/160 MHz |
| Operating voltage | 3.3V DC (NOT 5V tolerant on GPIO or power input) |
| Operating current | ~80 mA average, spikes to 200-300 mA during Wi-Fi transmit bursts |
| Flash memory | Typically 1MB–4MB onboard SPI flash, depending on module variant |
| GPIO | Multiple usable GPIO pins broken out (varies by exact module, typically 8-9), plus one analog input (ADC) |
| ADC | 1 analog input, 0-1V range (some breakouts add a resistor divider for 0-3.3V) |
| Programming interface | UART (TX/RX) for flashing via esptool or the Arduino IDE, requires GPIO0 pulled LOW to enter flash mode |
Pinout
| Pin | Name | Description |
|---|---|---|
| 1 | VCC | Power, 3.3V DC only — do not supply 5V |
| 2 | GND | Ground |
| 3 | TX / RXD | UART transmit/receive for programming and serial communication |
| 4 | GPIO0 | General I/O; must be pulled LOW at boot to enter flashing mode, HIGH for normal run mode |
| 5 | GPIO2 | General I/O; must be pulled HIGH at boot for normal operation |
| 6 | CH_PD / EN | Chip enable — must be pulled HIGH for the module to run |
| 7 | RST | Active-LOW reset pin |
| 8 | A0 (ADC) | Analog input, present on modules that expose it (e.g. ESP-12 based boards) |
All ESP8266 GPIO and power pins are strictly 3.3V — connecting 5V logic or supply will damage the chip, so use a logic-level shifter or a 5V-to-3.3V regulator when interfacing with 5V boards like the Arduino Uno. GPIO0 and GPIO2 have boot-mode roles (LOW/HIGH respectively for normal run) that must be respected or the module will fail to start correctly.
Variants
For quick prototyping, a NodeMCU or Wemos D1 Mini dev board is by far the easiest entry point since it includes USB programming and onboard regulation. Reach for a bare ESP-12 module only when designing a custom PCB or minimizing size/cost in a final build, and avoid the ESP-01 unless the project truly only needs 1-2 GPIO pins.
| Variant | Temp range | Hum range | Accuracy | Protocol | Price |
|---|---|---|---|---|---|
| ESP-12E / ESP-12F | ~$2-4 | ||||
| ESP-01 | ~$1-2 | ||||
| NodeMCU / Wemos D1 Mini (dev board) | ~$3-6 |