Vacus ESP32-LAN8720 PoE-R1 Module w/ IEEE 802.3af

The module can be powered in two ways. For development, connect a Micro-USB cable to your computer, which provides 5V power and a serial COM port via the onboard CP2102 chip. For final deployment, connect a standard Ethernet cable from an 802.3af-compliant PoE switch or injector to the RJ45 jack; this will deliver both data and power (up to 9W at 5V). Use the Arduino IDE or ESP-IDF with the selected COM port to upload your firmware. The BOOT and RST buttons, along with the CP2102's auto-reset circuitry, facilitate easy flashing without manual button presses.

For Arduino IDE development, use the standard Ethernet library or the more robust `ETH` library included in the ESP32 Arduino core. You will need to configure the correct PHY address (typically 0), the RMII clock pin (GPIO17 for CLK_OUT), and the power pin (GPIO5). In the ESP-IDF framework, enable Ethernet support via `menuconfig` under "Component Config" -> "Ethernet." Select the LAN8720 as the PHY and configure the same GPIO pins. Example code for both frameworks is available in the official Espressif repositories to establish a DHCP or static IP connection.

Power consumption depends on the ESP32's operational mode (active, modem sleep, deep sleep) and Ethernet link activity. With both Wi-Fi and Ethernet active, expect a typical current draw of 200-300mA from the 5V PoE rail. The onboard LM1117 linear regulator has a typical dropout voltage of 1.1V, so ensure the PoE input maintains above ~4.4V for stable 3.3V output. The AG9905M PoE controller and LM1117 may generate heat under full load; ensure adequate ventilation in enclosed spaces. For lowest power, utilize the ESP32's deep sleep mode and put the LAN8720A into a low-power state via software.