# ESP8266 ESP-01S WiFi Module

> Compact ESP8266-based WiFi dev board with 1MB flash, 2 GPIO pins, and 802.11 b/g/n. Runs Arduino, MicroPython, ESPHome, and Tasmota firmware for smart home and IoT projects.

## Quick Facts

- **Brand:** OpenELAB
- **Board Type:** ESP8266
- **Price:** ~$2.9
- **Product Readiness:** developer
- **CPU:** Tensilica L106 single-core @ 80/160MHz
- **CPU Architecture:** Xtensa
- **CPU Cores:** 1
- **RAM:** 64KB instruction RAM + 96KB data RAM
- **Flash:** 1MB
- **Power:** 3.0–3.6V
- **Operating Voltage:** 3.3V
- **Antenna:** Built-in PCB antenna

## Connectivity

- **Wifi:** 802.11 b/g/n

## Open Source

- **Firmware:** No
- **Schematics:** No
- **PCB Layout:** No

## Compatible Firmware

arduino, micropython, esphome, tasmota

## Use Cases

- smart-home
- iot
- smart-switch
- home-automation
- environmental-monitoring

## Components

- **ESP8266** (mcu): Espressif ESP8266EX single-core Tensilica L106 at 80/160MHz with integrated WiFi 802.11 b/g/n and 1MB flash. — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fwww.espressif.com%2Fsites%2Fdefault%2Ffiles%2Fdocumentation%2F0a-esp8266ex_datasheet_en.pdf&ref=openhardware.directory&product=esp8266-esp-01s&source=md-export)

## Protocols

- **UART**: TX: TX, RX: RX
- **GPIO**

## Description

## Overview

The ESP8266 ESP-01S is a compact WiFi module built around the Espressif ESP8266EX SoC, featuring a Tensilica L106 32-bit MCU running at 80/160MHz with integrated 802.11 b/g/n WiFi. With 1MB flash and 2 available GPIO pins, the ESP-01S is designed for space-constrained IoT applications where WiFi connectivity is the primary requirement.

Despite its tiny 24.8x14.3mm form factor with just an 8-pin 2x4 header, the ESP-01S is a fully programmable microcontroller that can run custom firmware. It supports Arduino IDE, MicroPython, ESPHome, and Tasmota, making it a popular choice for smart home relay control, WiFi-connected sensors, and MQTT-based IoT nodes.

The module is commonly paired with a relay adapter board (often included) for controlling mains-powered devices via WiFi. With ESPHome or Tasmota firmware, it integrates directly with Home Assistant for local smart home control without cloud dependencies.

## Key Features

- **ESP8266EX SoC**: 32-bit Tensilica L106 @ 80/160MHz
- **WiFi**: 802.11 b/g/n, WPA/WPA2, SoftAP + Station mode
- **Flash**: 1MB (8Mbit)
- **GPIO**: 2 usable pins (GPIO0, GPIO2)
- **UART**: TX/RX for programming and communication
- **Power**: 3.0–3.6V, ~170mA peak during transmission

## Pinout

| Pin | Function |
|-----|----------|
| VCC | 3.3V power supply |
| GND | Ground |
| TX | UART Transmit |
| RX | UART Receive |
| GPIO0 | General purpose I/O / Boot mode |
| GPIO2 | General purpose I/O |
| CH_PD | Chip Enable (tie to VCC) |
| RST | Reset (active low) |

## Where to Buy

- [OpenELAB](https://openhardware.directory/r?to=https%3A%2F%2Fopenelab.io%2Fproducts%2Fesp8266-esp-01s&ref=openhardware.directory&product=esp8266-esp-01s&source=md-export) — $2.90

## Resources

- [product](https://openhardware.directory/r?to=https%3A%2F%2Fopenelab.io%2Fproducts%2Fesp8266-esp-01s&ref=openhardware.directory&product=esp8266-esp-01s&source=md-export)

## Tags

`esp8266`, `esp-01s`, `wifi`, `iot`, `smart-home`, `arduino`, `micropython`, `esphome`, `tasmota`, `relay`

## Images

![ESP8266 ESP-01S WiFi Module](https://nbg1.your-objectstorage.com/openhardware-directory/entities/esp8266-esp-01s/542a146cf0aa.jpg)

---
[View full device page](https://openhardware.directory/devices/esp8266-esp-01s)