ESP-01 ESP8266 Serial WiFi Transceiver Module

A tiny, low-cost way to add WiFi

The ESP-01 is a compact wireless module powered by the ESP8266 chipset, with a built-in TCP/IP stack. It lets a microcontroller connect to WiFi networks over UART serial communication, working either as a standalone controller running its own firmware or as a simple WiFi adapter for another microcontroller.

It operates on 2.4 GHz, supporting the IEEE 802.11 b/g/n standards, and its ESP8266EX chipset gives reliable WiFi connectivity with both Station (STA) and Access Point (AP) modes.

Specifications

Operating voltage is 3.3 V DC, flash memory is 1 MB, and interfaces include SDIO 1.1/2.0, SPI and UART. The module has a compact size with an onboard PCB antenna, low power consumption and supports both AT commands over serial and custom firmware for more advanced use.

Because it runs at 3.3 V and needs a reasonably steady current during WiFi activity, avoid powering it directly from a 5 V Arduino's 3.3 V pin without checking the current it can supply, and use a proper 3.3 V regulator for reliable operation.

Who it is for

Hobbyists adding basic WiFi connectivity to an existing Arduino or other microcontroller project, or running very small standalone WiFi tasks on the ESP8266 itself.

Flashing custom firmware

If you plan to run your own firmware instead of AT commands, back up the original firmware version first and use a proper 3.3V programmer during flashing, since the module has no onboard USB-to-serial converter of its own. A separate USB-to-serial adapter set to 3.3V logic is the usual way to program it.

Questions buyers ask

What voltage does it need?

3.3 V DC.

How much flash memory does it have?

1 MB.

Which WiFi modes does it support?

Station (STA) and Access Point (AP).

How do I control it?

With AT commands over serial, or by flashing custom firmware.