Overview Pin Description Functional Description CPU 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 U.FL Connector Dimensions Product Handling Storage Conditions Electrostatic Discharge (ESD) Ultrasonic Vibration Appendix—Learning Resources Must-Read Documents Must-Have Resources www.espressif.com NRND Version 2.3 Espressif Systems Copyright © 2025 ESP-WROOM-02D/02U Datasheet Includes: ESP-WROOM-02D ESP-WROOM-02U Note： It is recommended to use the upgraded model: ESP8684-WROOM-02C/02UC NOT RECOMMENDED FOR NEW DESIGNS About This Guide This document provides introduction to the specifications of ESP-WROOM-02D and ESP- WROOM-02U hardware. Release Notes Date Version Release notes 2017.11 V1.0 First release. 2018.03 V1.1 Updated the figure of ESP-WROOM-02U dimensions. 2018.08 V1.2 • Updated Table 1-1 and Table 1-2; • Updated module dimensions; • Added PCB pattern; • Updated document cover. 2019.04 V1.3 • Added MSL information in table 1-2; • Added notes in Figure 5-1 and Figure 5-2. 2019.08 V1.4 Updated Chapter 6 Peripheral Schematics. 2019.12 V1.5 • Added a note for the reflow profile; • Added feedback links. 2019.12 V1.6 Updated a typo in ESP-WROOM-02D dimensions. 2020.07 V1.7 • Updated Note in Chapter 6; • Updated links in Appendix. 2022.03 V1.8 Added a link to RF certification in Table 1-2 2022.07 V1.9 • Updated links in Appendix; • Added Chapter 10 Product Handling. 2023.02 v2.0 Added description about footprint in Chapter 8. 2023.05 v2.1 Added ordering information in Table 1-1. 2023.06 v2.2 • Added a note on the cover page; • Updated two documents in Appendix. 2025.11 v2.3 Updated the product marketing status to Not Recommended for New Designs (NRND). 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. NRND Table of Contents 1. Overview ................................................................................................................................1 2. Pin Description ......................................................................................................................3 3. Functional Description ..........................................................................................................5 3.1. CPU! "..........................................................................................................................................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 ........................................................................................................14 7. Dimensions ..........................................................................................................................15 8. Recommended PCB Land Pattern .....................................................................................17 9. U.FL Connector Dimensions ...............................................................................................19 10.Product Handling .................................................................................................................20 10.1. Storage Conditions! "................................................................................................................20 10.2. Electrostatic Discharge (ESD)! ".................................................................................................20 10.3. Ultrasonic Vibration! "................................................................................................................20 A. Appendix—Learning Resources .........................................................................................21 A.1. Must-Read Documents! "..........................................................................................................21 A.2. Must-Have Resources!............................................................................................................22 NRND 1. Overview 1. Overview ESP-WROOM-02D and ESP-WROOM-02U are ESP8266EX-based modules developed by Espressif. Compared to ESP-WROOM-02, the RF performance of ESP-WROOM-02D and ESP-WROOM-02U are optimized. Besides, ESP-WROOM-02U integrates a U.FL connector. Please see Chapter 8 for details of U.FL connector. Table 1-1. ESP-WROOM-02D vs. ESP-WROOM-02U-1 Ordering Code Antenna In-Package Flash Ambient Temp Size (mm) ESP-WROOM-02D-H2 Onboard antenna 2 MB -40 °C ~ 105 °C (18.00 ± 0.10) x (20.00 ± 0.10) x (3.20 ± 0.10) ESP-WROOM-02D-N2 2 MB -40 °C ~ 85 °C ESP-WROOM-02D-N4 4 MB ESP-WROOM-02D-N16 16 MB ESP-WROOM-02U-H2 IPEX antenna 2 MB -40 °C ~ 105 °C (18.00 ± 0.10) x (14.30 ± 0.10) x (3.20 ± 0.10) ESP-WROOM-02U-N2 2 MB -40 °C ~ 85 °C ESP-WROOM-02U-N4 4 MB ESP-WROOM-02U-N16 16 MB 📖 Note: For more information on ESP8266EX, please refer to ESP8266EX Datasheet. Table 1-2. ESP-WROOM-02D/ESP-WROOM-02U Specifications Categories Items Specifications Certification RF certification See certificates from ESP-WROOM-02D and ESP- WROOM-02U Green certification RoHS, REACH Test 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) Peripheral interface UART/HSPI/I2C/I2S/IR Remote Control GPIO/PWM Operating voltage 2.7 V ~ 3.6 V Espressif / 1 23 Submit Documentation Feedback NRND 2025.11 1. Overview Hardware Operating current Average: 80 mA Minimum current delivered by power supply 500 mA External interface - Moisture sensitivity level Level 3 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 Categories Items Specifications Espressif / 2 23 Submit Documentation Feedback NRND 2025.11 2. Pin Description 2. Pin Description Figure 2-1 shows the pin distribution of the ESP-WROOM-02D. Figure 2-1. ESP-WROOM-02D Pin Layout (Top View) ESP-WROOM-02D and ESP-WROOM-02U have 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 📖 Note: The pin layout of ESP-WROOM-02U is the same with that of ESP-WROOM-02D, but it has no keepout zone for PCB antenna. Table 2-1. ESP-WROOM-02U/ESP-WROOM-02D 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. Espressif / 3 23 Submit Documentation Feedback NRND 2025.11 2. Pin Description 3 IO14 GPIO14; HSPI_CLK 4 IO12 GPIO12; HSPI_MISO 5 IO13 GPIO13; HSPI_MOSI; UART0_CTS 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 23 Submit Documentation Feedback NRND 2025.11 3. Functional Description 3. Functional Description 3.1. CPU The 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 the memory controller and memory units including ROM and SRAM. MCU can access the memory units through iBus, dBus, and AHB interfaces. All memory units can be accessed upon request. A memory arbiter determines the running sequence in the arrival order of requests. According to our current version of SDK, the SRAM space available to users is assigned as follows: • RAM size < 50 kB, that is, when ESP8266EX is working in Station mode and connects to the router, available space in the Heap + Data sector is around 50 kB. • There is no programmable ROM in ESP8266EX, therefore, the user program must be stored in an external SPI flash. 3.2.2. SPI Flash ESP8266EX supports SPI flash. Theoretically speaking, ESP8266EX can support an up- to-16-MB SPI flash. ESP-WROOM-02D and ESP-WROOM-02U currently integrate a 2-MB SPI flash. ESP- WROOM-02U supports these SPI modes: Standard SPI, DIO (Dual I/O), DOUT (Dual Output), QIO (Quad I/O) and QOUT (Quad Output). Espressif / 5 23 Submit Documentation Feedback NRND 2025.11 3. Functional Description 3.3. Crystal Oscillator ESP-WROOM-02U and ESP-WROOM-02D use 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. 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. Espressif / 6 23 Submit Documentation Feedback NRND 2025.11 3. Functional Description 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 23 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 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 - 2483.5 MHz Input reflection -　 - –10 dB Output Impedance - * - Ω 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 CCK, 11 Mbps - –91 - dBm Espressif / 8 23 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. 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 📖 Note: For the module that uses an IPEX antenna, the output impedance is 50 Ω. 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 23 Submit Documentation Feedback NRND 2025.11 4. Electrical Characteristics 4.4. Reflow Profile Figure 4-1. ESP-WROOM-02D/ESP-WROOM-02U 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, the 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 but only transmit data over long time lags, e.g., a temperature sensor that measures temperature every 100s. 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 23 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 Symb ol 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 23 Submit Documentation Feedback NRND 2025.11 5. Schematics 5. Schematics Figure 5-1. ESP-WROOM-02D Schematics 5 5 4 4 3 3 2 2 1 1 D D C C B B A A The values of C4, L1 and L2 vary with the actual PCB board. The values of C1 and C2 vary with the selection of the crystal. GPIO15 RST SD_D1 SD_D0 SD_CLK SD_CMD SD_D3 SD_D2 SD_CLK SD_CMD SD_D2 UTXDA 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 UTXD GND GND VDD33 GND GNDGND GND VDD33 GND VDD33 GND GND GND GND VDD33 GND GND GND VDD33 GND GND GND GND Title Size Document Number Rev Date: Sheet of ESP-WROOM-02D A3 22Monday, February 25, 2019 Title Size Document Number Rev Date: Sheet of ESP-WROOM-02D A3 22Monday, February 25, 2019 Title Size Document Number Rev Date: Sheet of ESP-WROOM-02D A3 22Monday, February 25, 2019 ANT1 1 2 C2 10pF D1 LESD8D3.3CAT5G J18 CON1 1 R1 12K±1% J5 CON1 1 C7 TBD(NC) C1 10pF C3 0.1uF L3 4.3nH J10 CON1 1 J13 CON1 1 C8 1uF(NC) J4 CON1 1 J15 CON1 1 J9 CON1 1 U3 FLASH /CS 1 DO 2 /WP 3 GND 4 DI 5 CLK 6 /HOLD 7 VCC 8 L1 TBD R3 200R J12 CON1 1 J3 CON1 1 C4 TBD L2 TBD J8 CON1 1 C6 1uF J2 CON1 1 U1 26MHz±10ppm XIN 1 GND 2 XOUT 3 GND 4 J11 CON1 1 J7 CON1 1 J1 CON1 1 J14 CON1 1 U2ESP8266EX 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 J16 CON1 1 J6 CON1 1 R2 499R±1% J17 CON1 1 Espressif / 12 23 Submit Documentation Feedback NRND 2025.11 5. Schematics Figure 5-2. ESP-WROOM-02U Schematics 5 5 4 4 3 3 2 2 1 1 D D C C B B A A The values of C4, L1 and L2 vary with the actual PCB board. The values of C1 and C2 vary with the selection of the crystal. GPIO15 RST SD_D1 SD_D0 SD_CLK SD_CMD SD_D3 SD_D2 SD_CLK SD_CMD SD_D2 UTXDA 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 UTXD GND GND VDD33 GND GNDGND GND GND VDD33 GND VDD33 GND GND GND GND VDD33 GND GND GND VDD33 GND GND GND GND Title Size Document Number Rev Date: Sheet of ESP-WROOM-02U A3 22Tuesday, February 26, 2019 Title Size Document Number Rev Date: Sheet of ESP-WROOM-02U A3 22Tuesday, February 26, 2019 Title Size Document Number Rev Date: Sheet of ESP-WROOM-02U A3 22Tuesday, February 26, 2019 C2 10pF D1 LESD8D3.3CAT5G J18 CON1 1 R1 12K±1% J5 CON1 1 C7 0.1uF(NC) C1 10pF C3 0.1uF L2 TBD L3 4.3nH J10 CON1 1 J13 CON1 1 C8 1uF(NC) J4 CON1 1 J15 CON1 1 J9 CON1 1 U3 FLASH /CS 1 DO 2 /WP 3 GND 4 DI 5 CLK 6 /HOLD 7 VCC 8 L1 TBD R3 200R J12 CON1 1 J3 CON1 1 J8 CON1 1 C6 1uF J2 CON1 1 U1 26MHz±10ppm XIN 1 GND 2 XOUT 3 GND 4 J11 CON1 1 CON1 IPEX 1 2 3 J7 CON1 1 J1 CON1 1 J14 CON1 1 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 C4 TBD J16 CON1 1 J6 CON1 1 R2 499R±1% J17 CON1 1 Espressif / 13 23 Submit Documentation Feedback NRND 2025.11 6. Peripheral Schematics 6. Peripheral Schematics Figure 6-1. ESP-WROOM-02D/ESP-WROOM-02U 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 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 / 14 23 Submit Documentation Feedback NRND 2025.11 7. Dimensions 7. Dimensions Figure 7-1. ESP-WROOM-02D Dimensions Module Length Unit: mm Module Width Top View Side View Bottom View 12.00±0.10 12.30±0.10 15.70±0.10 0.90±0.10 0.85±0.1 0.90±0.10 20.00±0.10 20.00±0.10 18.00±0.10 18.00±0.10 ESP-WROOM-02D DIMENSIONS 6.00±0.10 Antenna Area 1.50±0.10 0.90±0.10 1.50±0.10 12.00±0.10 PCB Thickness Module Thickness 0.80±0.10 3.20±0.10 0.90±0.10 0.45±0.10 󳊺 0.50±0.10 4.00±0.10 4.00±0.10 6.00±0.10 4.30±0.10 Espressif / 15 23 Submit Documentation Feedback NRND 2025.11 7. Dimensions Figure 7-2. ESP-WROOM-02U Dimensions PCB Thickness Module Thickness Module Length Unit: mm Module Width 18.00±0.10 14.30±0.10 3.94±0.10 3.90±0.10 4.37±0.10 8.12±0.10 0.90±0.10 0.85±0.1 3.20±0.10 0.80±0.10 18.00±0.10 14.30±0.10 12.00±0.10 1.50±0.10 0.90±0.10 ESP-WROOM-02U DIMENSIONS Top View Side View Bottom View 2.80±0.10 3.00±0.10 15.70±0.10 12.75±0.10 8.85±0.10 11.50±0.10 0.90±0.10 0.45±0.10 Espressif / 16 23 Submit Documentation Feedback NRND 2025.11 8. Recommended PCB Land Pattern 8. Recommended PCB Land Pattern This section provides the following resources for your reference: • Figures for recommended PCB land patterns with all the dimensions needed for PCB design. See Figure 8-1 and Figure 8-2. • Source files of recommended PCB land patterns to measure dimensions not covered in Figure 8-1 and Figure 8-2. You can view the source files for ESP-WROOM-02D and ESP-WROOM-02U with Autodesk Viewer. Figure 8-1. Recommended PCB Land Pattern of ESP-WROOM-02D Unit:mm 7.1 1.5x8=12 20 6 1.5 17.5 4 4.29 4 0.9 1 9 10 18 7.1 18 Espressif / 17 23 Submit Documentation Feedback NRND 2025.11 8. Recommended PCB Land Pattern Figure 8-2. Recommended PCB Land Pattern of ESP-WROOM-02U Unit:mm 1.5x8=12 1.5 17.5 4 4.29 4 0.9 1 9 10 18 7.1 1.4 14.3 18 Espressif / 18 23 Submit Documentation Feedback NRND 2025.11 9. U.FL Connector Dimensions 9. U.FL Connector Dimensions Figure 8-1. Dimensions of ESP-WROOM-02U’s U.FL Connector Unit: mm Espressif / 19 23 Submit Documentation Feedback NRND 2025.11 10. Product Handling 10. Product Handling 10.1. Storage Conditions The products sealed in moisture barrier bags (MBB) should be stored in a non-condensing atmospheric environment of < 40 °C and 90%RH. The module is rated at the moisture sensitivity level (MSL) of 3. After unpacking, the module must be soldered within 168 hours with the factory conditions 25 ± 5 °C and 60%RH. If the above conditions are not met, the module needs to be baked. 10.2. Electrostatic Discharge (ESD) • Human body model (HBM): ±2000 V • Charged-device model (CDM): ±500 V 10.3. Ultrasonic Vibration Avoid exposing Espressif modules to vibration from ultrasonic equipment, such as ultrasonic welders or ultrasonic cleaners. This vibration may induce resonance in the in- module crystal and lead to its malfunction or even failure. As a consequence, the module may stop working or its performance may deteriorate.! Espressif / 20 23 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. • ESP8266 Pin List Description: This link directs you to a list containing the type and function of every ESP8266 pin. • ESP8266 Hardware Design Guideline Description: This document provides a technical description of the ESP8266 series of products, including ESP8266EX, ESP-LAUNCHER and ESP-WROOM. • ESP8266 Technical Reference Description: This document provides an introduction to the interfaces integrated on ESP8266. Functional overview, parameter configuration, function description, application demos and other pieces of information are included. • ESP8266 Hardware Resources Description: This zip package includes manufacturing BOMs, schematics and PCB layouts of ESP8266 boards and modules. • ESP-WROOM-02 PCB Design and Module Placement Guide Description: The ESP-WROOM-02U 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 AT User Guide Description: This Get Started guide provides users with detailed information on what is ESP-AT, how to connect hardware, and how to download and flash AT firmware. • FAQ Espressif / 21 23 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 / 22 23 Submit Documentation Feedback NRND 2025.11 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. 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