ESP-01S ESP8266 Wi-Fi Module
Add powerful internet connectivity to your microcontrollers without adding bulk. The ESP-01S is an ultra-compact, highly upgraded version of the classic ESP-01 wireless module. Built around the revolutionary ESP8266 SoC, this tiny module features a full self-contained TCP/IP protocol stack, allowing your Arduino, AVR, or STM32 boards to seamlessly connect to any 2.4 GHz Wi-Fi network.
Whether you are pushing sensor data to an MQTT broker, building an standalone web server, or launching a smart home automation relay, the ESP-01S delivers robust wireless communication in a pocket-sized form factor.
Key Features
Upgraded ESP-01S Enhancements: Unlike the older ESP-01, the "S" variant features an optimized 4-layer PCB RF layout for improved Wi-Fi signal stability, an onboard 1MB flash memory chip, and removes the need for external pull-up resistors on the reset and enable pins.
Dual-Mode Operation: Functions flawlessly as an external Wi-Fi adapter using simple AT Commands over serial UART, or acts as a standalone microcontroller by flashing custom firmware via the Arduino IDE.
Rich Wi-Fi Protocols: Fully supports $802.11\text{ b/g/n}$ standards with three adaptable network modes: Station (client), AP (Access Point), or Dual AP+Station mode.
Integrated PCB Antenna: Features an onboard high-performance trace antenna, ensuring strong signal transmission and reception without needing bulky external antennas.
Smart Config & IoT Support: Out-of-the-box support for modern cloud ecosystems, Smart Link configuration, and secure Wi-Fi connections (WPA/WPA2).
Technical Specifications
Feature | Specification |
Microcontroller Core | ESP8266EX (32-bit RISC processor) |
Flash Memory Size | 1 MB (8 Mbit) |
Wireless Protocol | Wi-Fi 2.4 GHz ($802.11\text{ b/g/n}$) |
Logic/Operating Voltage | 3.3V DC (Strictly 3.3V only) |
Operating Current | Average: $\approx 80\text{ mA}$ | Peak Transmit: $$\approx 200\text{ mA$ |
Deep Sleep Current | < 10 µA |
Interface Pins | 2x4 Header (2.54mm pitch) |
Available GPIOs | 2 Channels (GPIO0, GPIO2) |
Serial Communication | UART (TX/RX) up to 115200 bps default |
Hardware Pinout Configuration
The ESP-01S breaks out 8 essential pins via a standard $2\times4$ male header block:
VCC & GND: 3.3V Power input and system ground.
TX & RX: Serial data communication pins used to send AT commands or flash custom software.
CH_PD (EN): Chip Enable pin. It is pulled HIGH internally on the ESP-01S to keep the module active.
RST: Hardware Reset pin (active LOW).
GPIO0 & GPIO2: General-purpose I/O pins. Note: GPIO0 must be pulled to GND during power-up to force the module into programming/firmware upload mode.
Common Applications
Smart Home Relays: Pair it with a 1-channel or 2-channel relay module to build phone-controlled smart switches.
Remote Weather Station: Read temperature/humidity data and upload metrics to IoT channels like ThingsSpeak or Blynk.
Serial-to-Wi-Fi Bridges: Turn any traditional desktop or legacy hardware project into an internet-connected smart machine.
Hardware Integration Warning: The ESP8266 silicon operates strictly on 3.3V logic levels. Interfacing the RX/TX lines directly with a 5V microcontroller (like the Arduino Uno) without a logic level converter or a 3.3V voltage regulator can permanently damage the module.
Package Includes:
1 x ESP-01S ESP8266 Wi-Fi Module