This guide shows how to get started with the ESP32-Ethernet-Kit development board and also provides information about its functionality and configuration options.
The :ref:`ESP32-Ethernet-Kit <get-started-esp32-ethernet-kit-v1.2>` is an Ethernet-to-Wi-Fi development board that enables Ethernet devices to be interconnected over Wi-Fi. At the same time, to provide more flexible power supply options, the ESP32-Ethernet-Kit also supports power over Ethernet (PoE).
It consists of two development boards, the Ethernet board A and the PoE board B. The :ref:`Ethernet board (A) <get-started-esp32-ethernet-kit-a-v1.2-layout>` contains Bluetooth/Wi-Fi dual-mode ESP32-WROVER-E module and IP101GRI, a Single Port 10/100 Fast Ethernet Transceiver (PHY). The `PoE board (B)`_ provides power over Ethernet functionality. The A board can work independently, without the board B installed.
For the application loading and monitoring, the Ethernet board (A) also features FTDI FT2232H chip - an advanced multi-interface USB bridge. This chip enables to use JTAG for direct debugging of ESP32 through the USB interface without a separate JTAG debugger.
FT2232H The FT2232H chip serves as a multi-protocol USB-to-serial bridge which can be programmed and controlled via USB to provide communication with ESP32. FT2232H also features USB-to-JTAG interface which is available on channel A of the chip, while USB-to-serial is on channel B. The FT2232H chip enhances user-friendliness in terms of application development and debugging. See `ESP32-Ethernet-Kit V1.2 Ethernet board (A) schematic`_.
IP101GRI (PHY) The physical layer (PHY) connection to the Ethernet cable is implemented using the `IP101GRI <http://www.bdtic.com/DataSheet/ICplus/IP101G_DS_R01_20121224.pdf>`_ chip. The connection between PHY and ESP32 is done through the reduced media-independent interface (RMII), a variant of the media-independent interface `(MII) <https://en.wikipedia.org/wiki/Media-independent_interface>`_ standard. The PHY supports the IEEE 802.3/802.3u standard of 10/100 Mbps.
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 Download button. Holding down **BOOT** and then pressing **EN** initiates Firmware Download mode for downloading firmware through the serial port.
Automatic firmware download is supported. If following steps and using software described in Section `Start Application Development`_, users don't need to do any operation with BOOT button or EN button.
This board coverts power delivered over the Ethernet cable (PoE) to provide a power supply for the Ethernet board (A). The main components of the PoE board (B) are shown on the block diagram under `Functionality Overview`_.
To take advantage of the PoE functionality the **RJ45 Port** of the Ethernet board (A) should be connected with an Ethernet cable to a switch that supports PoE. When the Ethernet board (A) detects 5 V power output from the PoE board (B), the USB power will be automatically cut off.
- Four female (left) and four male (right) header pins for connecting the PoE board (B) to :ref:`Ethernet board (A) <get-started-esp32-ethernet-kit-a-v1.2-layout>`. The pins on the left accept power coming from a PoE switch. The pins on the right deliver 5 V power supply to the Ethernet board (A).
When in On position, this DIP switch is routing listed GPIOs to FT2232H to provide JTAG functionality. When in Off position, the GPIOs may be used for other purposes.
The ethernet MAC and PHY under RMII working mode need a common 50 MHz reference clock (i.e. RMII clock) that can be provided either externally, or generated from internal ESP32 APLL (not recommended).
By default, the ESP32-Ethernet-Kit is configured to provide RMII clock for the IP101GRI PHY's 50M_CLKO output. The clock signal is generated by the frequency multiplication of 25 MHz crystal connected to the PHY. For details, please see the figure below.
Please note that the PHY is reset on power up by pulling the RESET_N signal down with a resistor. ESP32 should assert RESET_N high with GPIO5 to enable PHY. Only this can ensure the power-up of system. Otherwise ESP32 may enter download mode (when the clock signal of REF_CLK_50M is at a high logic level during the GPIO0 power-up sampling phase).
Another option is to source the RMII Clock from internal ESP32 APLL, see figure below. The clock signal coming from GPIO0 is first inverted, to account for transmission line delay, and then supplied to the PHY.
To implement this option, users need to remove or add some RC components on the board. For details please refer to `ESP32-Ethernet-Kit V1.2 Ethernet board (A) schematic`_, sheet 2, location D2. Please note that if the APLL is already used for other purposes (e.g. I2S peripheral), then you have no choice but use an external RMII clock.
The allocation of the ESP32 (MAC) pins to IP101GRI (PHY) is shown in the table below. Implementation of ESP32-Ethernet-Kit defaults to Reduced Media-Independent Interface (RMII).
The allocation of all pins under the ESP32's *RMII Interface* is fixed and cannot be changed either through IO MUX or GPIO Matrix. REF_CLK can only be selected from GPIO0, GPIO16 or GPIO17 and it can not be changed through GPIO Matrix.
1. The ESP32 pins GPIO16 and GPIO17 are not broken out to the ESP32-WROVER-E module and therefore not available for use. If you need to use these pins, please solder a module without PSRAM memory inside, e.g. the ESP32-WROOM-32D or ESP32-SOLO-1.
1. To prevent the power-on state of the GPIO0 from being affected by the clock output on the PHY side, the RESET_N signal to PHY defaults to low, turning the clock output off. After power-on you can control RESET_N with GPIO5 to turn the clock output on. See also `RMII Clock Sourced Externally by PHY`_. For PHYs that cannot turn off the clock output through RESET_N, it is recommended to use a crystal module that can be disabled/enabled externally. Similarly like when using RESET_N, the oscillator module should be disabled by default and turned on by ESP32 after power-up. For a reference design please see `ESP32-Ethernet-Kit V1.2 Ethernet board (A) schematic`_.
2. The ESP32 pins GPIO16 and GPIO17 are not broken out to the ESP32-WROVER-E module and therefore not available for use. If you need to use these pins, please solder a module without PSRAM memory inside, e.g. the ESP32-WROOM-32D or ESP32-SOLO-1.
1. Set the **Function Switch** on the :ref:`Ethernet board (A) <get-started-esp32-ethernet-kit-a-v1.2-layout>` to its default position by turning all the switches to **ON**.
Proceed to :doc:`../../get-started/index`, where Section :ref:`get-started-step-by-step` will quickly help you set up the development environment and then flash an example project onto your board.
After setting up the development environment and testing the board, you can configure and flash the :example:`ethernet/basic` example. This example has been created for testing Ethernet functionality. It supports different PHY, including **IP101GRI** installed on :ref:`get-started-esp32-ethernet-kit-v1.2`.
