1. Overview

The ESP32 Ethernet DC Development Board is a robust wired-Ethernet ESP32 platform designed for industrial, automation, and embedded control applications.

It combines an ESP32-D0WD-V3 (rev 3.1, 16 MB flash) with a LAN8720A Ethernet PHY, wide-range 8–60 V DC input, onboard switching regulation, and USB-C programming.

This board is intended for permanently powered, network-connected devices where reliability, clear pin ownership, and wide supply tolerance are required.

⚠️ This board does NOT support Power over Ethernet (PoE).
Ethernet is data only.

2. Key Features

• ESP32-D0WD-V3 (revision 3.1)

  • Dual-core Xtensa LX6

  • Up to 240 MHz

  • Wi-Fi + Bluetooth (optional use)

  • 16 MB external flash

• Wired Ethernet

  • LAN8720A PHY

  • 10/100 Mbps

  • RMII interface

  • RJ45 with integrated magnetics

  • Link / activity LEDs

• Wide Input Power

  • VIN: 8–60 V DC

  • High-efficiency buck regulator

  • Onboard 5 V and 3.3 V rails

  • Suitable for industrial and automotive environments

• USB-C Interface

  • Firmware upload

  • Serial debug console

  • Auto-reset / auto-boot circuitry

  • USB power diode-ORed with external supply

• Clearly Broken-Out I/O

  • ESP32 GPIO headers

  • Power rails on headers

  • Reset and BOOT access

3. Power Architecture

Power Inputs

• VIN (8–60 V DC) via screw terminal

• USB-C 5 V (programming / light operation)

Power Path Behavior

• USB 5 V is diode-isolated from the main board supply

• External VIN and USB may be connected simultaneously

• The higher voltage source automatically powers the board

• No back-feeding into the USB port

Power Rails

• Buck regulator generates 5 V

• LDO generates 3.3 V for ESP32 and Ethernet PHY

⚠️ Ethernet does not provide power (no PoE)

4. Programming & Operation

Firmware Upload

• Firmware is uploaded via USB-C

• USB provides:

  • Programming

  • Serial monitoring

• Ethernet is not used for flashing

Important Notes

• Disconnect external loads during firmware upload if the board is powered only from USB

• USB may not supply enough current for all peripherals

• Board is designed for continuous powered operation from VIN

5. Ethernet Interface (LAN8720A)

Hardware Configuration

• Ethernet PHY is hard-wired to the ESP32 using RMII

• GPIO assignments are fixed in hardware

• Pins cannot be remapped

Software Requirement

• Ethernet must be enabled in firmware

• The firmware must reference the predefined GPIO pins

6. Ethernet Pin Mapping (Fixed)

⚠️ RESERVED – DO NOT USE AS GPIO

These pins are permanently assigned to Ethernet and are not available for general I/O:

7. ESP32 GPIO Availability

General-Purpose GPIO (Available)

GPIO1 and GPIO3 are used by USB serial but may be repurposed if UART0 is not required.

Input-Only GPIO

Notes:

• No output capability

• No internal pull-ups/downs

• Ideal for sensors and analog inputs

Boot / Strapping Pins (Use with Care)

These pins affect boot behavior and must not be driven incorrectly during reset.

8. Safety & Usage Notes

• No PoE support — data only

• Do not drive Ethernet GPIOs

• Do not overload USB power

• Ensure proper grounding for industrial environments

• Use regulated VIN supply

9. Typical Applications

• Industrial controllers

• Automation gateways

• Ethernet-connected sensors

• Remote monitoring devices

• Networked power and control systems

• DIN-rail mounted controllers

10. Summary

This board is designed for real-world deployment, not just prototyping:

• Wide VIN range

• Proper Ethernet implementation

• Clear pin ownership

• Safe power OR-ing

• Long-term stable operation

It provides a solid foundation for wired ESP32 systems where reliability and clarity matter.