Overview Pin Description Functional Description MCU Memory Internal SRAM and ROM SPI Flash Crystal Oscillator Interface Description Electrical Characteristics Electrical Characteristics Wi-Fi Radio Power Consumption Reflow Profile Electrostatic Discharge Schematics Peripheral Schematics Dimensions Recommended PCB Land Pattern Appendix—Learning Resources Must-Read Documents Must-Have Resources www.espressif.com Version 3.7 Espressif Systems Copyright © 2025 ESP-WROOM-02 Datasheet Note： It is recommended to use the upgraded model: ESP8684-WROOM-02C NOT RECOMMENDED FOR NEW DESIGNS About This Guide This document provides introduction to the specifications of ESP-WROOM-02 hardware. Release Notes Date Version Release notes 2015.12 V0.5 First release. 2016.01 V0.6 Updated Section 3.2.2. 2016.02 V0.7 • Added Appendix—Notices. • Updated Chapter 1. 2016.04 V0.8 Updated the flash size and PAD (bottom) size. 2016.06 V0.9 Updated the flash size. 2016.06 V1.0 • Added Appendix—Notices—B.5. • Updated Figure 2-1. 2016.08 V1.1 Updated the operating temperature range. 2016.11 V1.2 • Added Appendix—Learning Resources. • Added “ESP-WROOM-02 Peripheral Schematics” in Chapter 5. 2016.11 V2.0 • Added Section 4.8 “Electrostatic Discharge”. • Updated Figure 5-1. ESP-WROOM-02 Schematics. 2016.12 V2.1 • Changed the minimum working voltage from 3.0 V to 2.5 V. • Changed the power consumption during Deep-sleep from 10 μA to 20 μA. 2017.02 V2.2 Updated Section 3.3. 2017.04 V2.3 • Added the module's dimensional tolerance; • Changed the input impedance value in Table 4-4 and 4-5 from 50 Ω to 39 + j6 Ω; • Added Figure 4-1 Reflow Profile. Not Recommended For New Designs (NRND) 2017.09 V2.4 • Added Documentation Change Notification and the official link for downloading Product Certificates; • Updated the supply voltage to 2.7 V ~ 3.6 V; • Updated Figure 2-1 ESP-WROOM-02 Pin Layout and added a note to it; • Updated Chapter 4: Collated electrical-characteristics-related data into Table 4-1; collated Wi-Fi-radio-related data into Table 4-2 and updated the output power parameters; • Updated Chapter 5 Schematics and added a note; • Added Chapter 6 Dimensions. • Deleted Appendix B—Notices. 2017.10 V2.5 Updated the note to ESP-WROOM-02 Peripheral Schematics in Chapter 5. 2018.03 V2.6 • Deleted the note in Chapter 1; • Deleted the “RF certification” column and added a new “Certificates” section with all acquired certifications listed in Table 1-1; • Updated Section 3.1 and Section 3.2; • Updated Figure 4-1. 2018.04 V2.7 Deleted the “Bluetooth certification” part in Table 1-1. 2018.06 V2.8 • Updated Figure 1-1 and Figure 6-1; • Updated Chapter 1 for module size. 2018.08 V2.9 • Updated Chapter 1 for module size, and add information of reliability test items; • Updated Figure 6-1 Dimensions of ESP-WROOM-02; • Added Chapter 7 Recommended PCB Land Pattern; • Updated the cover page. 2019.08 V3.0 Updated Chapter 6 Peripheral Schematics. 2019.12 V3.1 • Added a note for the reflow profile; • Added feedback links. 2020.07 V3.2 • Updated Note in Chapter 6; • Updated links in Appendix. 2021.08 V3.3 Added the “Not Recommended For New Designs (NRND)” watermark and footers. 2022.03 V3.4 Added a link to RF certification in Table 1-1 2023.06 v3.5 • Added a note on the cover page; • Updated two documents in Appendix. 2023.09 v3.6 Updated Figure 6-1 and Figure 7-1. 2025.11 v3.7 Updated the product marketing status to Not Recommended for New Designs (NRND). Date Version Release notes Not Recommended For New Designs (NRND) Documentation Change Notification Espressif provides email notifications to keep customers updated on changes to technical documentation. Please subscribe at https://www.espressif.com/en/subscribe. Certification Download certificates for Espressif products from https://www.espressif.com/en/ certificates. Not Recommended For New Designs (NRND) Table of Contents 1. Overview ......................................................................................................................1 2. Pin Description ............................................................................................................3 3. Functional Description ..................................................................................................5 3.1. MCU ...............................................................................................................................5 3.2. Memory ..........................................................................................................................5 3.2.1. Internal SRAM and ROM ......................................................................................5 3.2.2. SPI Flash ............................................................................................................5 3.3. Crystal Oscillator ..............................................................................................................6 3.4. Interface Description .......................................................................................................6 4. Electrical Characteristics ...............................................................................................8 4.1. Electrical Characteristics ..................................................................................................8 4.2. Wi-Fi Radio ......................................................................................................................8 4.3. Power Consumption ........................................................................................................9 4.4. Reflow Profile .................................................................................................................10 4.5. Electrostatic Discharge ....................................................................................................11 5. Schematics ................................................................................................................12 6. Peripheral Schematics .................................................................................................13 7. Dimensions ................................................................................................................14 8. Recommended PCB Land Pattern .................................................................................15 A. Appendix—Learning Resources ....................................................................................16 A.1. Must-Read Documents ...................................................................................................16 A.2. Must-Have Resources .....................................................................................................17 Not Recommended For New Designs (NRND) 1. Overview 1. Overview Espressif provides the SMD module—ESP-WROOM-02 that integrates ESP8266EX. The module has been adjusted to get the best RF performance. We recommend using ESP- WROOM-02 for tests or for further development. The module size is (18.00 ± 0.20) mm x (20.00 ± 0.20) mm x (2.80 ± 0.15) mm. The type of flash used on this module is an SPI flash with a package size of SOP 8-150 mil. The gain of the on-board PCB antenna is 2 dBi. Figure 1-1. ESP-WROOM-02 Module 📖 Note: For more information on ESP8266EX, please refer to ESP8266EX Datasheet. Espressif / 1 18 Submit Documentation Feedback NRND 2025.11 1. Overview Table 1-1. ESP-WROOM-02 Specifications Categories Items Specifications Certification RF certification See certificates for ESP-WROOM-02 Wi-Fi certifaction Wi-Fi Alliance Green certification RoHS, REACH Te st Reliablity HTOL/HTSL/uHAST/TCT/ESD Wi-Fi Wi-Fi protocols 802.11 b/g/n Frequency range 2.4 GHz ~ 2.5 GHz (2400 MHz ~ 2483.5 MHz) Hardware Peripheral interface UART/HSPI/I2C/I2S/IR Remote Control GPIO/PWM Operating voltage 2.7 V ~ 3.6 V Operating current Average: 80 mA Minimum current delivered by power supply 500 mA Operating temperature range –40 °C ~ 85 °C Storage temperature –40 °C ~ 85 °C Package size (18.00 ± 0.20) mm x (20.00 ± 0.20) mm x (2.80±0.15) mm External interface - Software Wi-Fi mode Station/SoftAP/SoftAP + Station Security WPA/WPA2 Encryption WEP/TKIP/AES Firmware upgrade UART Download/OTA (via network)/Download and write firmware via host Software development Supports Cloud Server Development/SDK for custom firmware development Network protocols IPv4, TCP/UDP/HTTP/FTP User configuration AT Instruction Set, Cloud Server, Android/iOS app Espressif / 2 18 Submit Documentation Feedback NRND 2025.11 2. Pin Description 2. Pin Description Figure 2-1 shows the pin distribution of the ESP-WROOM-02. Figure 2-1. ESP-WROOM-02 Pin Layout (Top View) ESP-WROOM-02 has 18 pins. Please see the pin definitions in Table 2-1. 19GND PCB ANTENNA GND IO16 TOUT RST IO5 GND TXD RXD IO4 3V3 EN IO14 IO12 IO13 IO15 IO2 IO0 GND 9 8 7 6 5 4 3 2 1 10 11 12 13 14 15 16 17 18 Table 2-1. ESP-WROOM-02 Pin Definitions No. Pin Name Functional Description 1 3V3 3.3 V power supply (VDD) 📖 Note: It is recommended the maximum output current a power supply provides be of 500 mA or above. 2 EN Chip enable pin. Active high. 3 IO14 GPIO14; HSPI_CLK 4 IO12 GPIO12; HSPI_MISO 5 IO13 GPIO13; HSPI_MOSI; UART0_CTS Espressif / 3 18 Submit Documentation Feedback NRND 2025.11 2. Pin Description 6 IO15 GPIO15; MTDO; HSPICS; UART0_RTS Pull down. 7 IO2 GPIO2; UART1_TXD Floating (internal pull-up) or pull up. 8 IO0 GPIO0 • UART download: pull down. • Flash boot: floating or pull up. 9 GND GND 10 IO4 GPIO4 11 RXD UART0_RXD, receive end in UART download; GPIO3 12 TXD UART0_TXD, transmit end in UART download, floating or pull up; GPIO1 13 GND GND 14 IO5 GPIO5 15 RST Reset 16 TOUT It can be used to test the power-supply voltage of VDD3P3 (Pin3 and Pin4) and the input power voltage of TOUT (Pin6). These two functions cannot be used simultaneously. 17 IO16 GPIO16; used for Deep-sleep wake-up when connected to RST pin. 18 GND GND No. Pin Name Functional Description Espressif / 4 18 Submit Documentation Feedback NRND 2025.11 3. Functional Description 3. Functional Description 3.1. MCU ESP8266EX integrates a Tensilica L106 32-bit RISC processor, which achieves extra-low power consumption and reaches a maximum clock speed of 160 MHz. The Real-Time Operating System (RTOS) and Wi-Fi stack allow 80% of the processing power to be available for user application programming and development. The CPU includes the interfaces as below. • Programmable RAM/ROM interfaces (iBus), which can be connected with memory controller, and can also be used to visit flash. • Data RAM interface (dBus), which can connected with memory controller. • AHB interface which can be used to visit the register. 3.2. Memory 3.2.1. Internal SRAM and ROM ESP8266EX Wi-Fi SoC integrates memory controller and memory units including SRAM and ROM. MCU can access the memory units through iBus, dBus, and AHB interfaces. All memory units can be accessed upon request, while a memory arbiter will decide the running sequence according to the time when these requests are received by the processor. According to our current version of SDK, SRAM space available to users is assigned as below. • RAM size < 50 kB, that is, when ESP8266EX is working under the Station mode and connects to the router, programmable space accessible in heap + data section is around 50 kB. • There is no programmable ROM in the SoC, therefore, user program must be stored in an external SPI flash. 3.2.2. SPI Flash ESP8266EX uses external SPI flash to store user programs, and supports up to 16 MB memory capacity theoretically. Espressif / 5 18 Submit Documentation Feedback NRND 2025.11 3. Functional Description ESP-WROOM-02 currently integrates a 2-MB SPI flash. ESP-WROOM-02 supports these SPI modes: Standard SPI, DIO (Dual I/O), DOUT (Dual Output), QIO (Quad I/O) and QOUT (Quad Output). 3.3. Crystal Oscillator ESP-WROOM-02 uses a 26-MHz crystal oscillator. The accuracy of the crystal oscillator should be ±10 PPM. When using the download tool, please select the right type of crystal oscillator. In circuit design, capacitors C1 and C2 which connect to the earth are added to the input and output terminals of the crystal oscillator respectively. The values of the two capacitors can be flexible, ranging from 6 pF to 22 pF, however, the specific capacitive values depend on further testing of, and adjustment to, the overall performance of the whole circuit. Normally, the capacitive values of C1 and C2 are within 10 pF for the 26-MHz crystal oscillator. 3.4. Interface Description Table 3-1. Interface Description Interface Pin Functional Description HSPI IO12 (MISO), IO13 (MOSI), IO14 (CLK), IO15 (CS) Connects to SPI Flash, display screen, and MCU. PWM IO12 (R), IO15 (G), IO13 (B) Currently the PWM interface has four channels, but users can extend it to eight channels. PWM interface can realize the control of LED lights, buzzers, relays, electronic machines, etc. IR IO14 (IR_T), IO5 (IR_R) The functionality of the infrared remote control interface can be realized via software programming. The interface uses NEC coding, modulation, and demodulation. The frequency of the modulated carrier signal is 38 kHz. ADC TOUT Tests the power supply voltage of VDD3P3 (Pin3 and Pin4) and the input power voltage of TOUT (Pin6). However, these two functions cannot be used simultaneously. This interface is typically used in sensors. I2C IO14 (SCL), IO2 (SDA) Connects to external sensors and display screens, etc. Espressif / 6 18 Submit Documentation Feedback NRND 2025.11 3. Functional Description UART UART0: TXD (U0TXD), RXD (U0RXD), IO15 (RTS), IO13 (CTS) UART1: IO2 (TXD) Communicates with the UART device. Downloading: U0TXD + U0RXD or GPIO2 + U0RXD Communicating: (UART0): U0TXD, U0RXD, MTDO (U0RTS), MTCK (U0CTS) Debugging: UART1_TXD (GPIO2) can be used to print debugging information. By default, UART0 will output some printed information when you power on ESP8266EX. If this issue influences some specific applications, users can exchange the inner pins of UART when initializing ESP8266EX, that is, exchange U0TXD and U0RXD with U0RTS and U0CTS. Users can connect MTDO and MTCK to the serial port of the external MCU to realize the communication. I2S I2S input: IO12 (I2SI_DATA) ; IO13 (I2SI_BCK ); IO14 (I2SI_WS); Collects, processes and transmits audio data. I2S output: IO15 (I2SO_BCK ); IO3 (I2SO_DATA); IO2 (I2SO_WS ). Interface Pin Functional Description Espressif / 7 18 Submit Documentation Feedback NRND 2025.11 4. Electrical Characteristics 4. Electrical Characteristics 4.1. Electrical Characteristics 4.2. Wi-Fi Radio 📖 Note: Unless otherwise specified, measurements are based on VDD = 3.3 V, TA = 25 °C. Table 4-1. Electrical Characteristics Parameter Symbol Min Typ Max Unit Storage temperatue - –40 Normal 85 ℃ Operating temperature - –40 20 85 ℃ Maximum soldering temperature (Condition: IPC/JEDEC J-STD-020) - - - 260 ℃ Supply voltage VDD 2.7 3.3 3.6 V Input logic level low V IL –0.3 - 0.25 VDD V Input logic level high V IH 0.75 VDD - VDD + 0.3 V Output logic level low V OL - - 0.1 VDD V Output logic level high V OH 0.8 VDD - - V Table 4-2. Wi-Fi Radio Characteristics Description Min Typ Max Unit Input frequency 2412 - 2484 MHz Input reflection -　 - –10 dB Output Power PA output power at 72.2 Mbps 13 14 15 dBm PA output power in 11b mode 19.5 20 20.5 dBm Sensitivity DSSS, 1 Mbps - –98 - dBm Espressif / 8 18 Submit Documentation Feedback NRND 2025.11 4. Electrical Characteristics 4.3. Power Consumption The following power consumption data were obtained from the tests with a 3.3 V power supply and a voltage stabilizer, in 25 °C ambient temperature. All data are based on 50% duty cycle in continuous transmission mode. DSSS, 1 Mbps - –98 - dBm CCK, 11 Mbps - –91 - dBm 6 Mbps (1/2 BPSK) - –93 - dBm 54 Mbps (3/4 64-QAM) - –75 - dBm HT20, MCS7 (65 Mbps, 72.2 Mbps) - –72 - dBm Adjacent channel rejection OFDM, 6 Mbps - 37 - dB OFDM, 54 Mbps - 21 - dB HT20, MCS0 - 37 - dB HT20, MCS7 - 20 - dB Description Min Typ Max Unit Table 4-3. Power Consumption Modes Min Typ Max Unit Tx 802.11 b, CCK 11 Mbps, POUT = +17 dBm - 170 - mA Tx 802.11 g, OFDM 54 Mbps, POUT = +15 dBm - 140 - mA Tx 802.11 n, MCS7, POUT = +13 dBm - 120 - mA Rx 802.11 b, 1024 bytes packet length, -80 dBm - 50 - mA Rx 802.11 g, 1024 bytes packet length, -70 dBm - 56 - mA Rx 802.11 n, 1024 bytes packet length, -65 dBm - 56 - mA Modem-sleep① - 15 - mA Light-sleep② - 0.9 - mA Deep-sleep③ - 20 - μA Power Off - 0.5 - μA Espressif / 9 18 Submit Documentation Feedback NRND 2025.11 4. Electrical Characteristics 4.4. Reflow Profile Figure 4-1. ESP-WROOM-02 Reflow Profile 📖 Notes: ① Modem-sleep is used when such applications as PWM or I2S require the CPU to be working. In cases where Wi-Fi connectivity is maintained and data transmission is not required, the Wi-Fi Modem circuit can be shut down to save power, according to 802.11 standards (such as U-APSD). For example, in DTIM3, when ESP8266EX sleeps for 300 ms and wakes up for 3 ms to receive Beacon packages from AP, the overall average current consumption is about 15 mA. ② Light-sleep is used for applications whose CPU may be suspended, such as Wi-Fi switch. In cases where Wi-Fi connectivity is maintained and data transmission is not required, Wi-Fi Modem circuit and CPU can be shut down to save power, according to 802.11 standards (such as U-APSD). For example, in DTIM3, when ESP8266EX sleeps for 300 ms and wakes up for 3 ms to receive Beacon packages from AP, the overall average current consumption is about 0.9 mA. ③ Deep-sleep is for applications that do not require Wi-Fi connectivity and only transmit data over long time lags, e.g., a temperature sensor that measures temperature every 100 s. For example, when ESP8266EX sleeps for 300 s then wakes up to connect to AP (taking about 0.3 ~ 1 s), the overall average current consumption is far less than 1 mA. The current consumption of 20 μA was obtained at the voltage of 2.5 V. 50 150 0 25 1 ~ 3℃/s 0 200 250 200 -1 ~ -5℃/s Cooling zone 100 217 50 100 250 Reflow zone 217℃ 60 ~ 90s Temperature (℃) Preheating zone 150 ~ 200℃ 60 ~ 120s Ramp-up zone Peak Temp. 235 ~ 250℃ Soldering time > 30s Time (sec.) Ramp-up zone — Temp.: <150℃ Time: 60 ~ 90s Ramp-up rate: 1 ~ 3℃/s Preheating zone — Temp.: 150 ~ 200℃ Time: 60 ~ 120s Ramp-up rate: 0.3 ~ 0.8℃/s Reflow zone — Temp.: >217℃ 60 ~ 90s; Peak Temp.: 235 ~ 250℃ (<245℃ recommended) Time: 30 ~ 70s Cooling zone — Peak Temp. ~ 180℃ Ramp-down rate: -1 ~ -5℃/s Solder — Sn&Ag&Cu Lead-free solder (SAC305) Espressif / 10 18 Submit Documentation Feedback NRND 2025.11 4. Electrical Characteristics 4.5. Electrostatic Discharge 📖 Note: Solder the module in a single reflow. If the PCBA requires multiple reflows, place the module on the PCB during the final reflow. Table 4-4. Electrostatic Discharge Parameters Name Symbol Reference Level Max Unit Electrostatic Discharge (Human - Body Model) VESD (HBM) Temperature: 23 ± 5 ℃ Basedon ANSI/ESDA/JEDEC JS - 001 - 2014 2 2000 V Electrostatic Discharge (Charged - Device Model) VESD (CDM) Temperature: 23 ± 5 ℃ Basedon JEDEC EIA/JESD22 - C101F C2 500 Espressif / 11 18 Submit Documentation Feedback NRND 2025.11 5. Schematics 5. Schematics Figure 5-1. ESP-WROOM-02 Schematics GPIO15 RST SD_D1 SD_D0 SD_CLK SD_CMD SD_D3 SD_D2 SD_CLK SD_CMD SD_D2 UTXD WIFI_ANT GPIO14 GPIO12 URXD GPIO13 GPIO16 GPIO0 CH_PU GPIO2 GPIO4 GPIO5 CH_PU GPIO14 GPIO12 GPIO13 GPIO15 GPIO2 GPIO0 GPIO4 GPIO5 URXD UTXD RST TOUT GPIO16 TOUT SD_D3 SD_D0 SD_D1 GND GND VDD33 GND GNDGND GND GND VDD33 GND VDD33 GND GND GND GND VDD33 GND GND GND VDD33 GND GND GND Pin.1 3V3 Pin.2 CH_PU/EN Pin.3 IO14 Pin.4 IO12 Pin.5 IO13 Pin.6 IO15 Pin.7 IO2 Pin.8 IO0 Pin.9 GND Pin.10 IO4 Pin.11 RXD Pin.12 TXD Pin.13 GND Pin.14 IO5 Pin.15 RST Pin.16 TOUT Pin.17 IO16 Pin.18 GND Pin.19 GND(P_GND) ANT1 1 2 C2 10pF D1 ESD3.3V88D-C R1 12K±1% C1 10pF C3 0.1uF C4 8.2pF U3 FLASH /CS 1 DO 2 /WP 3 GND 4 DI 5 CLK 6 /HOLD 7 VCC 8 L1 2.4pF R3 200 C6 1uF U1 26MHz ± 10ppm XIN 1 GND 2 XOUT 3 GND 4 U2 ESP8266EX VDDA 1 LNA 2 VDD3P3 3 VDD3P3 4 VDD_RTC 5 TOUT 6 CHIP_EN 7 XPD_DCDC 8 MTMS 9 MTDI 10 VDDPST 11 MTCK 12 MTDO 13 GPIO2 14 GPIO0 15 GPIO4 16 VDDPST 17 SD_DATA_2 18 SD_DATA_3 19 SD_CMD 20 SD_CLK 21 SD_DATA_0 22 SD_DATA_1 23 GPIO5 24 U0RXD 25 U0TXD 26 XTAL_OUT 27 XTAL_IN 28 VDDD 29 VDDA 30 RES12K 31 EXT_RSTB 32 GND 33 C5 10uF L2 1.5nH Espressif / 12 18 Submit Documentation Feedback NRND 2025.11 6. Peripheral Schematics 6. Peripheral Schematics Figure 5-2. ESP-WROOM-02 Peripheral Schematics EN IO14 IO12 IO13 IO15 IO2 IO0 IO16 IO5 IO4 ADC RXD RST TXD VDD33 GND VDD33 GND GND GNDGND GND GND J2 BOOT OPTION 1 2 U1 ESP_WROOM_02 3V3 1 EN 2 IO14 3 IO12 4 IO13 5 IO15 6 IO2 7 IO0 8 GND1 9 IO4 10 RXD 11 TXD 12 GND2 13 IO5 14 RST 15 TOUT 16 IO16 17 GND3 18 P_GND 19 J1 UART DOWNLOAD 1 2 3 C2 0.1uF C3 0.1uF R2 10K C1 10uF R1 10K 📖 Note: 1. Soldering Pad 19 to the Ground of the base board is not necessary for a satisfactory thermal performance. If users do want to solder it, they need to ensure that the correct quantity of soldering paste is applied. 2. To ensure the power supply to the ESP8266EX chip during the power-up, it is advised to add an RC delay circuit at the EN pin. The recommended setting for the RC delay circuit is usually R = 10 kΩ and C = 0.1 uF. However, specific parameters should be adjusted based on the power-up timing of the module and the power-up and reset timing of the ESP8266 chip. For ESP8266EX’s Power-up and Reset Timing Diagram, please refer to Electrical Characteristics in ESP8266EX Datasheet. 3. To improve module’s anti-inference capability, it is advised to reserve an RC delay circuit at the RST pin. The recommended setting for the RC delay circuit is usually R= 10 kΩ and C = 0.1 uF. Espressif / 13 18 Submit Documentation Feedback NRND 2025.11 7. Dimensions 7. Dimensions Figure 6-1. Dimensions of ESP-WROOM-02 2.8±0.15 0.8 0.80 1.15 20±0.2 6 18 x 0.9 12 0.9 1.5 Top View Side View Bottom View 18 x 0.85 18 x 0.9 7.87 18±0.2 18 x 0.45 Unit: mm 18 x Ø0.55 15.65 12.25 Ø1 4.29 4.29 6.30 Espressif / 14 18 Submit Documentation Feedback NRND 2025.11 8. Recommended PCB Land Pattern 8. Recommended PCB Land Pattern Figure 7-1. Recommended PCB Land Pattern of ESP-WROOM-02 20.00 6.00 6.30 4.40x4.40 1 9 10 18 10.11 18.00 Unit: mm Copper Via for thermal pad Antenna Area 1.15x1.15 0.90 1.50 18x0.90 18x1.50 12.00 0.50 Espressif / 15 18 Submit Documentation Feedback NRND 2025.11 Appendix A A. Appendix—Learning Resources A.1. Must-Read Documents • ESP-AT Instruction User Guide Description: This document provides users with detailed information on what is ESP- AT, how to connect hardware, and how to download and flash AT firmware. • ESP8266 SDK Getting Started Guide Description: This document describes how to get started withESP8266_RTOS_SDK, which is the official development framework for theESP8266EXchip. • 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. • 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 Espressif / 16 18 Submit Documentation Feedback NRND 2025.11 Appendix A 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 / 17 18 Submit Documentation Feedback NRND 2025.11 Not Recommended For New Designs (NRND) 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 © 2023 Espressif Inc. All rights reserved. Espressif IoT Team www.espressif.com