Overview Functional Description How to Flash a Board Hardware Preparation Hardware Setup Software Setup Board Dimensions Hardware Reference Block Diagram Power Supply Options Header Blocks Appendix—Learning Resources Must-Read Documents Must-Have Resources www.espressif.com ESP8266-DevKitS User Guide Version 1.1 Espressif Systems Copyright © 2025 End of Life (EOL) About This Guide This user guide provides information on ESP8266-DevKitS-development board. Release Notes Documentation Change Notification Espressif provides email notifications to keep customers updated on changes to technical documentation. Please subscribe here. Certification Download certificates for Espressif products from here. Date Version Release notes 2025.05 V1.1 End of Life. 2020.02 V1.0 Initial release. www.espressif.com Tables of Contents 1. Overview ................................................................................................................................1 2. Functional Description ..........................................................................................................2 3. How to Flash a Board ............................................................................................................4 3.1. Hardware Preparation! "................................................................................................................4 3.2. Hardware Setup! ".........................................................................................................................4 3.3. Software Setup! "..........................................................................................................................4 4. Board Dimensions .................................................................................................................5 5. Hardware Reference ..............................................................................................................6 5.1. Block Diagram! "............................................................................................................................6 5.2. Power Supply Options! "...............................................................................................................6 5.3. Header Blocks! "............................................................................................................................6 A. Appendix—Learning Resources ...........................................................................................8 A.1. Must-Read Documents! "..............................................................................................................8 A.2. Must-Have Resources!................................................................................................................9 1. Overview! 1. Overview ESP8266-DevKitS is Espressif’s flashing board designed specifically for ESP8266. It can be used to flash an ESP8266 module without soldering the module to the power supply and signal lines. With a module mounted, ESP8266-DevKitS can also be used as a mini development board like ESP8266-DevKitC. ESP8266-DevKitS supports the following ESP8266 modules: - ESP-WROOM-02 - ESP-WROOM-02D - ESP-WROOM-02U Espressif /91 End of Life (EOL) 2025.05 2. Functional Description! 2. Functional Description Figure 2-1. ESP8266-DevKitS This chapter introduces key components, interfaces and controls of ESP8266-DevKitS development board: • Spring Pins Connect and fix the module. These spring pins fit castellated holes on the module. • 2.54 mm Female Headers Connect to jumper wires and other development boards. For description of female headers, please refer to 5.3 Header Blocks. • USB-to-UART Bridge A single chip USB-UART bridge provides up to 3 Mbps transfers rates. Espressif /92 End of Life (EOL) 2025.05 2. Functional Description! • LDO 5V-to-3.3V Low dropout voltage regulator (LDO). • Boot Button Download button. Holding down the Boot button and pressing the EN button initiates the firmware download mode. Then users can download firmware through the serial port. • Micro USB Port/Micro USB Connector USB interface. Power supply for the board and the communication interface between a computer and the board. • EN Button Reset button. Pressing this button resets the system. • Power On LED Turns on when the USB or power supply is connected to the board. Espressif /93 End of Life (EOL) 2025.05 3. How to Flash a Board 3. How to Flash a Board 3.1. Hardware Preparation • 1 x ESP8266 module of your choice • 1 x USB 2.0 cable (Standard-A to Micro-B) • 1 x PC loaded with Windows, Linux or Mac OS 3.2. Hardware Setup Please mount a module of your choice onto your ESP8266-DevKitS according to the following steps: • Gently put your module on the ESP8266-DevKitS board. Make sure that castellated holes on your module are aligned with spring pins on the board. • Press your module down into the board until it clicks. • Check whether all spring pins are inserted into castellated holes. If there are some misaligned spring pins, place them into castellated holes with tweezers. 3.3. Software Setup For step-by-step introductions, please refer to ESP8266 Quick Start Guide. 📖 Note: 1. To flash binary files, the ESP32 chip should be set to UART boot mode. This can be done either by the flash tool automatically, or by holding down the Boot button and tapping the EN button. 2. After binary files have been flashed, please reset or power up your ESP32 module again to run the flashed application (this step is executed automatically by the flash tool by default). Espressif /94 End of Life (EOL) 2025.05 4. Board Dimensions 4. Board Dimensions Figure 4-1. Board Dimensions Espressif /95 End of Life (EOL) 2025.05 5. Hardware Reference 5. Hardware Reference 5.1. Block Diagram Figure 5-1. ESP8266-DevKitS Block Diagram 5.2. Power Supply Options There are three mutually exclusive ways to provide power to the board: • Micro USB port, default power supply • 5V and GND header pins • 3V3 and GND header pins It is advised to use the first option: micro USB port. 5.3. Header Blocks Table 5-1. Header Block Location Label Signal L1 G GND L2 3V3 VDD 3V3 L3 3V3 VDD 3V3 Espressif /96 End of Life (EOL) 2025.05 5. Hardware Reference L4 EN CHIP_EN L5 G GND L6 14 GPIO14 L7 12 GPIO12 L8 13 GPIO13 L9 15 GPIO15 L10 2 GPIO2 L11 0 GPIO0 L12 G GND L13 5V External 5V L14 G GND L15 G GND R1 G GND R2 16 GPIO16 R3 G GND R4 TX U0TXD R5 RX U0RXD R6 G GND R7 4 GPIO4 R8 RST EXT_RSTB R9 5 GPIO5 R10 ADC To TOUT after a voltage divider R11 G GND R12 G GND R13 G GND R14 G GND R15 G GND Espressif /97 End of Life (EOL) 2025.05 Appendix A A. Appendix—Learning Resources A.1. Must-Read Documents • ESP8266-DevKitS Reference Design Description: This zip package include ESP8266-DevKitS schematics, PCB layout, gerber and BOM files, and spring design files. • ESP8266 Quick Start Guide Description: This document is a quick user guide to getting started with ESP8266. It includes an introduction to the ESP-LAUNCHER, how to download firmware on to the board and run it, how to compile the AT application, structure and the debugging method of RTOS SDK. Basic documentation and other related resources for the ESP8266 are also provided. • ESP8266 SDK Getting Started Guide Description: This document takes ESP-LAUNCHER and ESP-WROOM-02 as examples to introduce how to use ESP8266 SDK. The contents include preparations before compilation, SDK compilation and firmware download. • ESP-WROOM-02 Datasheet Description: ESP-WROOM-02 is a SMD module that integrates ESP8266EX. The module has been adjusted to get the best RF performance. • ESP-WROOM-02D/ESP-WROOM-02U Datasheet Description: ESP-WROOM-02D and ESP-WROOM-02U are ESP8266EX-based modules developed by Espressif. Compared with ESP-WROOM-02, the RF performance of ESP-WROOM-02D and ESP-WROOM-02U are optimized. • ESP-WROOM-02 Reference Design Description: This zip package includes ESP-WROOM-02 hardware downloading resources, manufacturing specifications, BOM and schematics. • ESP-WROOM-02D/ESP-WROOM-02U Reference Design Description: This zip package includes ESP-WROOM-02D and ESP-WROOM-02U module reference design resources, including schematics, PCB layout, gerber files and BOM lists. " • ESP-WROOM-02 PCB Design and Module Placement Guide Description: The ESP-WROOM-02 module is designed to be soldered to a host PCB. This document compares six different placements of the antenna on a host board and provides notes on designing PCB. Espressif /8 10 End of Life (EOL) 2025.05 Appendix A • ESP8266 Hardware Resources Description: This zip package includes manufacturing specifications of the ESP8266 board and the modules, manufacturing BOM and schematics. • ESP8266 AT Command Examples Description: This document introduces some specific examples of using Espressif AT commands, including single connection as a TCP Client, UDP transmission and transparent transmission, and multiple connection as a TCP server. • ESP8266 AT Instruction Set Description: This document provides lists of AT commands based on ESP8266_NONOS_SDK, including user-defined AT commands, basic AT commands, Wi-Fi AT commands and TCP/IP-related AT commands. It also introduces the downloading of AT firmware into flash. • TCP/UDP UART Passthrough Test Demonstration Description: This guide is intended to help users run a TCP & UDP passthrough test on the ESP8266 IoT platform. • FAQ A.2. Must-Have Resources • ESP8266 SDKs Description: This website page provides links to the latest version of ESP8266 SDK and the older ones. • ESP8266 Tools Description: This website page provides links to the ESP8266 flash download tools and ESP8266 performance evaluation tools. • ESP8266 App • ESP8266 Certification and Test Guide • ESP8266 BBS • ESP8266 Resources Espressif /9 10 End of Life (EOL) 2025.05 Disclaimer and Copyright Notice Information in this document, including URL references, is subject to change without notice. THIS DOCUMENT IS PROVIDED AS IS WITH NO WARRANTIES WHATSOEVER, INCLUDING ANY WARRANTY OF MERCHANTABILITY, NON-INFRINGEMENT, FITNESS FOR ANY PARTICULAR PURPOSE, OR ANY WARRANTY OTHERWISE ARISING OUT OF ANY PROPOSAL, SPECIFICATION OR SAMPLE. All liability, including liability for infringement of any proprietary rights, relating to use of information in this document is disclaimed. No licenses express or implied, by estoppel or otherwise, to any intellectual property rights are granted herein. The Wi-Fi Alliance Member logo is a trademark of the Wi-Fi Alliance. The Bluetooth logo is a registered trademark of Bluetooth SIG. All trade names, trademarks and registered trademarks mentioned in this document are property of their respective owners, and are hereby acknowledged. Copyright © 2025 Espressif Inc. All rights reserved. Espressif IoT Team" www.espressif.com