Espressif Systems ESP32-Ethernet-Kit

The Ethernet Board A also features the FTDI FT2232HL Multi-Interface USB Bridge IC. This chip enables the use of JTAG for direct debugging of ESP32 through the USB interface without a separate JTAG debugger.

• ESP32-WROVER-E: This ESP32 module features 64-Mbit PSRAM for flexible extended storage and data processing capabilities.
• GPIO Header 2: Five, unpopulated through-hole solder pads to provide access to selected GPIOs of ESP32. 
• Flow Control: Jumper header with access to the board signals. 
• Function Switch: DIP switch used to configure the functionality of selected GPIOs of ESP32. 
• Tx/Rx LEDs: Two LEDs to show the status of UART transmission.
• GPIO Header 3: Provides access to some GPIOs of ESP32 that can be used depending on the position of the Function Switch.
• FT2232: Multi-protocol USB-to-serial bridge, which can be programmed and controlled via USB to provide communication with ESP32. Includes USB-to-JTAG interface on channel A and USB-to-serial on channel B.
• USB Port: USB interface. Power supply for the board as well as the communication interface between a computer and the board.
• Power Switch: Power On/Off Switch. Toggling toward the Boot button powers the board on, and toggling away from the Boot powers the board off.
• 5V Input: External 5V power supply for autonomous board operation.
• 5V Power On LED: Indicates power being supplied to the board from either a USB or 5V input.
• DC-DC Converter: Provides DC 5V to 3.3V conversion with output current up to 2A.
• Board B Connectors: Header pins for mounting the PoE Board B.
• IP101GRI (PHY): The Physical Layer (PHY) connection to the Ethernet cable is implemented using the IP101GRI chip. The connection between PHY and ESP32 is done through the reduced media-independent interface (RMII), a variant of the media-independent interface (MII) standard. The PHY supports the IEEE 802.3 / 802.3u standard of 10/100Mbps.
• RJ45 Port: Ethernet network data transmission port.
• Magnetics Module: The Magnetics are part of the Ethernet specification to protect against faults and transients, including rejection of common mode signals between the transceiver IC and the cable. The magnetics also provide galvanic isolation between the transceiver and the Ethernet device.
• Link/Activity LEDs: Two LEDs (green and red) that respectively indicate the "Link" and "Activity" statuses of the PHY.
• Boot Button: The download button initiates Firmware Download mode for downloading firmware through the serial port.
• CH_PU Button: Reset button.
• GPIO Header 1: This header provides six unpopulated through-hole solder pads connected to spare GPIOs of ESP32. 

• Board A Connector: Four female header pins for mounting this board onto Ethernet Board A.
• External Power Terminals: Optional power supply to the PoE Board B.