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The ESP8266 Wi-Fi Module is one of the most widely used and affordable solutions for adding wireless connectivity to embedded and IoT systems. Developed by Espressif Systems, this compact System-on-Chip (SoC) combines powerful processing capabilities, low power consumption, and integrated Wi-Fi support in a single device. This article will discuss the ESP8266 Wi-Fi module’s overview, pinout, specifications, features, applications, programming circuit, and more.
The ESP8266 Wi-Fi Module is a low-cost System-on-Chip (SoC) developed by Espressif Systems, designed to provide full Wi-Fi networking capabilities and microcontroller functionality. Operating on the IEEE 802.11 b/g/n standard at 2.4 GHz, it features a 32-bit Tensilica processor running up to 160 MHz, integrated TCP/IP stack, and support for UART, SPI, and I²C communication. This makes it a versatile choice for projects that require wireless connectivity without additional Wi-Fi hardware.
The ESP8266 can function either as a Wi-Fi adapter for microcontrollers like Arduino or as a standalone controller running custom firmware. Its compact design, 3.3V low-power operation, and multiple variants such as ESP-01, NodeMCU, and Wemos D1 Mini make it ideal for IoT applications including smart devices, automation systems, and wireless sensors.
If you are interested in purchasing the ESP8266 Wi-Fi Module, feel free to contact us for pricing and availability.
| Pin No. | Pin Name | Function |
| 1 | GND (Ground) | Connects to ground of the circuit. |
| 2 | TX (Transmit) | Serial data transmit pin; used to send data to other devices (e.g., Arduino RX). |
| 3 | GPIO2 | General Purpose Input/Output pin – can be used for digital input/output. |
| 4 | CH_EN (Chip Enable) | Must be connected to 3.3V to enable the chip (active high). |
| 5 | GPIO0 | General Purpose Input/Output pin; also used to enter programming mode (connect to GND during flashing). |
| 6 | RST (Reset) | Used to reset the module; connect to GND momentarily to reset. |
| 7 | RX (Receive) | Serial data receive pin; used to receive data from other devices (e.g., Arduino TX). |
| 8 | VCC (3.3V) | Power supply pin (connect to regulated 3.3V, not 5V). |
| Model | Manufacturer | Connectivity | Processor |
| ESP32 Dev Board (ESP-WROOM-32) | Espressif Systems | Wi-Fi + Bluetooth | Dual-core Xtensa LX6 @ up to 240 MHz |
| ESP32-C3 (Seeed Studio XIAO) | Espressif / Seeed Studio | Wi-Fi + Bluetooth LE | RISC-V Single-core @ 160 MHz |
| ESP32 D1 Mini | AZ-Delivery | Wi-Fi + Bluetooth | Dual-core Xtensa LX6 |
| ESP32 Ultra-Low Power Board | Espressif / Generic | Wi-Fi + Bluetooth | Dual-core Xtensa LX6 |
| ESP32 38-Pin Dev Board | Makerlab / Generic | Wi-Fi + Bluetooth | Dual-core Xtensa LX6 |
| Realtek RTL8710 | Realtek | Wi-Fi | ARM Cortex-M3 @ 166 MHz |
| Specification | Details |
| Manufacturer | Espressif Systems |
| Model | ESP8266 (commonly ESP-01, ESP-12E, ESP-12F, NodeMCU, etc.) |
| Architecture / Core | 32-bit Tensilica Xtensa® L106 microcontroller |
| CPU Clock Speed | 80 MHz (can be overclocked to 160 MHz) |
| Operating Voltage | 3.0V – 3.6V (typical 3.3V) |
| Power Consumption | < 170 mA (active mode); < 20 µA (deep sleep mode) |
| Flash Memory | 512 KB to 16 MB (varies by module) |
| SRAM | 64 KB instruction + 96 KB data |
| Storage Interface | SPI Flash |
| Wi-Fi Standard | IEEE 802.11 b/g/n (2.4 GHz) |
| Wi-Fi Modes | Station / Soft Access Point / Station + AP |
| Network Protocols | TCP, UDP, HTTP, FTP, MQTT |
| Security | WPA/WPA2 Encryption |
| GPIO Pins | Up to 17 (depends on module variant) |
| Analog Input | 1 × 10-bit ADC (on some modules) |
| Interfaces Supported | UART, SPI, I²C (bit-bang), PWM |
| Reset / Enable Pins | RST (Reset), CH_PD (Chip Enable, active HIGH) |
| Operating Temperature | –40°C to +125°C |
| Antenna | PCB trace antenna or external (via IPEX connector) |
| Dimensions (ESP-01 module) | Approx. 24.8 mm × 14.3 mm |
| Firmware Options | AT Command Firmware, NodeMCU (Lua), Arduino Core, MicroPython |
| Programming Interface | UART (TX/RX), USB (via adapter or NodeMCU board) |
Integrated DNS and DHCP support: Allows automatic IP assignment and hostname resolution without manual configuration.
Multiple simultaneous connections: Supports up to 5 TCP clients in AP mode for flexible networking.
Built-in SPI flash file system (SPIFFS): Enables storage of web pages, configuration files, or data logs directly on the module.
OTA (Over-The-Air) firmware updates: Allows remote program upgrades without requiring physical access to the module.
Wi-Fi Direct (P2P) communication: Enables device-to-device networking without the need for a router.
SoftAP configuration via web portal: Simplifies setup using a mobile browser interface.
Multicast and broadcast networking: Supports data transmission to multiple devices simultaneously.
Built-in real-time clock (RTC) memory: Preserves data during deep sleep cycles for improved reliability.
Automatic power-saving mechanisms: Includes modem-sleep and light-sleep modes to enhance energy efficiency.
IPv4 and IPv6 support: Operates with IPv4 and offers potential for IPv6 in advanced firmware builds.
Integrated watchdog timer (WDT): Provides system recovery and ensures stability during long-running operations.
Programmable PWM frequency: Supports adjustable frequencies from 1 kHz to 10 kHz for LED dimming and motor control.
Regulatory certifications: Fully FCC, CE, and IC certified for use in wireless applications.
Extensive SDK support: Offers Non-OS SDK and RTOS SDK for flexible custom firmware development.
Seamless cloud integration: Works smoothly with popular IoT platforms like Google Firebase, AWS IoT, and Adafruit IO.
Built-in debugging and diagnostic logs: Accessible through UART for easier firmware troubleshooting.
Catalogue
FPGA / CPLD
Memory
MOS 
MCU 
DSP
OCEP
Secondary 
Other