The ESP32-C3-WROOM-02U-N4 is a surface-mount module built around the Espressif ESP32-C3 RISC-V single-core microcontroller. It integrates 4 MB flash, 384 kB ROM, and 408 kB SRAM on the module. The PCB trace antenna means the module does not need an external antenna connector or a separate antenna part — the trade-off is that the board ground plane and nearby metal affect the resonance, so the antenna matching network should be tuned on the final PCB stack-up. Start from the Espressif antenna tuning guide in the hardware design guidelines. Rated conducted output power is 20.5 dBm.
This covers outdoor gateways, engine-bay telematics, and factory-floor sensor bridges without a separate temperature-grade variant. The supply voltage is 3.0 V to 3.6 V; a 3.3 V rail with ±5 % tolerance stays inside the window. Receive current is 82–84 mA; transmit current ranges from 280 mA to 345 mA depending on output power setting.
Serial interfaces and peripheral set
The ESP32-C3 exposes ADC, GPIO, I²C, I²S, SPI, JTAG, PWM, UART, and USB serial interfaces on the module pads. The USB serial peripheral can serve as a direct programming interface — no external USB-to-UART bridge needed for firmware updates. Bluetooth v5.0 supports LE with 2 Mbps PHY, advertising extensions, and mesh profile — the same BLE stack that runs on the larger ESP32 series. The 802.11b/g/n radio delivers up to 150 Mbps PHY rate in HT40 mode.