This article serves as your complete technical datasheet and reference guide. We will dissect every line of the official specifications, decode the confusing pinout, address the infamous "3.3V vs. 5V" power dilemma, and show you how to program it.
The is a breakout board manufactured by Ai-Thinker. It houses the original ESP8266 microcontroller (ESP8266EX) on a compact PCB with two key components: a 2x4 pin header and a PCB trace antenna.
The pinout is the most confusing part of this module. There are two versions: (original) and ESP-01S (revised). They look identical but have different internal pull-up resistors.
