Description
Product Overview
The ESP-WROOM-02U (4MB) is a highly integrated, certified Wi-Fi module developed by Espressif Systems, the original creator of the ESP8266 ecosystem. This module represents the official, production-ready implementation of the ESP8266EX chip, featuring 4 MB (32 Mbit) of SPI flash memory—double the storage capacity of the standard version—and a U.FL/IPEX connector that allows you to attach an external antenna for enhanced wireless range and flexibility .
What distinguishes the ESP-WROOM-02U from its counterparts (like the ESP-WROOM-02D) is its external antenna interface and narrow form factor. While the 02D variant uses a PCB trace antenna and measures 20mm wide, the 02U integrates a U.FL connector and measures just 14.3mm wide, making it ideal for space-constrained designs where antenna placement flexibility is required . The external antenna capability allows you to choose the optimal antenna for your specific application—whether that’s a high-gain antenna for long-range communication or a flexible antenna for tight enclosures.
At its heart lies the ESP8266EX chip—a Tensilica L106 32-bit RISC processor running at up to 160 MHz, with 4 MB (32 Mbit) of SPI flash memory and 50 kB of user-available SRAM . The module supports 802.11 b/g/n Wi-Fi protocols at 2.4 GHz, delivering up to +20.5 dBm output power and excellent receiver sensitivity down to -98 dBm .
Designed and manufactured by Espressif, the ESP-WROOM-02U comes preloaded with AT command firmware, allowing you to add Wi-Fi connectivity to any microcontroller using simple serial commands. It can also be reprogrammed as a standalone IoT processor using the Arduino IDE, MicroPython, or ESP-IDF .
Key Features
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4 MB Flash Memory: Equipped with 4 MB (32 Mbit) of SPI flash memory—double the capacity of standard ESP-WROOM-02 modules—providing ample storage for complex firmware, web interfaces, and robust OTA (Over-The-Air) updates with room for dual firmware partitions .
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U.FL/IPEX Antenna Connector: Features an external antenna connector, allowing you to use a high-gain or custom antenna for extended range and flexibility in enclosure design. No onboard PCB antenna is present .
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Narrow Form Factor: Measures just 18.0 mm × 14.3 mm × 3.2 mm—significantly narrower than the ESP-WROOM-02D (20mm wide)—making it ideal for space-constrained designs .
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Official Espressif Module: Designed and manufactured by Espressif Systems, the creators of the ESP8266, ensuring the highest quality and reliable RF performance .
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Integrated 32-bit Processor: Powered by the Tensilica L106 32-bit RISC processor running at up to 160 MHz, capable of running application code independently without an external microcontroller .
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Complete Wi-Fi Solution: Supports 802.11 b/g/n protocols at 2.4 GHz with an external antenna interface. Delivers up to +20.5 dBm output power with receiver sensitivity down to -98 dBm .
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Preloaded AT Command Firmware: Ships with industrial-grade AT firmware that allows control via simple serial commands, enabling rapid integration with any microcontroller.
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Multiple Operating Modes: Supports Station (STA), SoftAP (Access Point), and SoftAP + STA modes, enabling devices to connect to existing networks or create their own .
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Rich Peripheral Interfaces: Provides UART, HSPI, I2C, I2S, IR Remote Control, PWM, and 10-bit ADC interfaces, allowing connection to a wide variety of sensors, actuators, and display devices .
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Ultra-Low Power Consumption: Features multiple sleep modes with deep sleep current as low as 20 µA, making it ideal for battery-powered applications .
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Global Regulatory Certifications: Certified with FCC, CE-RED, TELEC, KCC, IC, NCC, SRRC, and RoHS, simplifying the certification process for commercial products .
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Wide Operating Temperature: Rated for operation from -40°C to +85°C, suitable for demanding industrial environments and outdoor installations .
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Upgradable Firmware: Supports local serial flashing and OTA (Over-The-Air) updates for flexible firmware management .
Technical Specifications
| Parameter | Operating Value |
|---|---|
| Module Model | ESP-WROOM-02U (4MB) |
| Core Chip | ESP8266EX |
| Processor | Tensilica L106 32-bit RISC |
| Clock Speed | 80 MHz (supports 160 MHz) |
| Flash Memory | 4 MB (32 Mbit) |
| SRAM | 50 kB (user-available) |
| Operating Voltage | 2.7 V – 3.6 V DC (3.3 V typical) |
| Average Operating Current | 80 mA |
| Transmit Current | 120 mA – 170 mA |
| Receive Current | 50 mA – 56 mA |
| Deep Sleep Current | 20 µA |
| Minimum Supply Current Required | 500 mA |
| Wireless Standard | 802.11 b/g/n |
| Frequency Band | 2.4 GHz (2400 MHz – 2483.5 MHz) |
| Output Power | +20.5 dBm |
| Receiver Sensitivity | -98 dBm |
| Data Rate | Up to 72.2 Mbps |
| Modulation | 64-QAM, BPSK, CCK, OFDM |
| Antenna | U.FL/IPEX connector (external antenna required) |
| Interfaces | UART, HSPI, I2C, I2S, IR Remote Control, PWM, ADC |
| ADC Resolution | 10-bit |
| GPIO Pins | 11 usable GPIO (16 total pins with dedicated functions) |
| Operating Temperature | -40°C to +85°C |
| Storage Temperature | -40°C to +85°C |
| Module Dimensions | 18.0 mm × 14.3 mm × 3.2 mm |
| Package Type | SMD-18 (castellated edges) |
| Moisture Sensitivity Level | MSL 3 |
| Certifications | FCC, CE-RED, TELEC, KCC, IC, NCC, SRRC, RoHS |
| Weight | Approx. 2 g |




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