.. _esp32_ethernet_kit:

ESP32-ETHERNET-KIT
##################

The ESP32-Ethernet-Kit 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).

.. _get-started-esp32-ethernet-kit-v1.2-overview:

.. figure:: img/esp32-ethernet-kit-v1.2-overview.jpg
    :align: center
    :alt: ESP32-Ethernet-Kit V1.2
    :figclass: align-center

    ESP32-Ethernet-Kit V1.2 Overview

Overview
--------

ESP32-Ethernet-Kit is an ESP32-based development board produced by
`Espressif <https://espressif.com>`_.

It consists of two development boards, the Ethernet board A and the PoE
board B. The `Ethernet board (A)`_ 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.

.. _get-started-esp32-ethernet-kit-v1.2:

.. figure:: img/esp32-ethernet-kit-v1.2.jpg
    :align: center
    :alt: ESP32-Ethernet-Kit V1.2
    :figclass: align-center

    ESP32-Ethernet-Kit V1.2

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.


Functionality Overview
----------------------

The block diagram below shows the main components of ESP32-Ethernet-Kit
and their interconnections.

.. figure:: img/esp32-ethernet-kit-v1.1-block-diagram.jpg
    :align: center
    :alt: ESP32-Ethernet-Kit block diagram
    :figclass: align-center

    ESP32-Ethernet-Kit block diagram


Functional Description
----------------------

The following figures and tables describe the key components, interfaces,
and controls of the ESP32-Ethernet-Kit.

.. _get-started-esp32-ethernet-kit-a-v1.2-layout:


Ethernet Board (A)
^^^^^^^^^^^^^^^^^^

.. figure:: img/esp32-ethernet-kit-a-v1.2-layout.jpg
    :align: center
    :alt: ESP32-Ethernet-Kit V1.2
    :figclass: align-center

    ESP32-Ethernet-Kit - Ethernet board (A) layout

The table below provides description starting from the picture's top right
corner and going clockwise.

.. list-table:: Table 1  Component Description
  :widths: 40 150
  :header-rows: 1

  * - Key Component
    - Description
  * - 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. For details, see `GPIO Header 2`_.
  * - Function Switch
    - A 4-bit DIP switch used to configure the functionality of selected GPIOs
      of ESP32. For details see `Function Switch`_.
  * - Tx/Rx LEDs
    - Two LEDs to show the status of UART transmission.
  * - 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 <https://dl.espressif.com/dl/schematics/SCH_ESP32-Ethernet-Kit_A_V1.2_20200528.pdf>`_.
  * - 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 the switch to **5V0** position powers the
      board on, toggling to **GND** position powers the board off.
  * - 5V Input
    - The 5 V power supply interface can be more convenient when the board is
      operating autonomously (not connected to a computer).
  * - 5V Power On LED
    - This red LED turns on when power is supplied to the board, either from
      USB or 5 V Input.
  * - DC/DC Converter
    - Provided DC 5 V to 3.3 V conversion, output current up to 2 A.
  * - Board B Connectors
    - A pair male and female header pins for mounting the `PoE board (B)`_
  * - 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.
  * - EN Button
    - Reset button.
  * - GPIO Header 1
    - This header provides six unpopulated through-hole solder pads connected
      to spare GPIOs of ESP32. For details, see `GPIO Header 1`_.

PoE Board (B)
^^^^^^^^^^^^^

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`_.

The PoE board (B) has the following features:

* Support for IEEE 802.3at
* Power output: 5 V, 1.4 A

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.

.. figure:: img/esp32-ethernet-kit-b-v1.0-layout.jpg
    :align: center
    :alt: ESP32-Ethernet-Kit - PoE board (B)
    :figclass: align-center

    ESP32-Ethernet-Kit - PoE board (B) layout

.. list-table:: Table  PoE board (B)
  :widths: 40 150
  :header-rows: 1

  * - Key Component
    - Description
  * - Board A Connector
    - Four female (left) and four male (right) header pins for connecting the
      PoE board (B) to `Ethernet board (A)`_. 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).
  * - External Power Terminals
    - Optional power supply (26.6 ~ 54 V) to the PoE board (B).

.. _get-started-esp32-ethernet-kit-v1.2-setup-options:


Setup Options
-------------

This section describes options to configure the ESP32-Ethernet-Kit hardware.


Function Switch
^^^^^^^^^^^^^^^

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.

=======  ================
DIP SW   GPIO Pin
=======  ================
 1       GPIO13
 2       GPIO12
 3       GPIO15
 4       GPIO14
=======  ================


RMII Clock Selection
^^^^^^^^^^^^^^^^^^^^

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).

.. note::

    For additional information on the RMII clock selection, please refer to
    `ESP32-Ethernet-Kit V1.2 Ethernet board (A) Schematic <https://dl.espressif.com/dl/schematics/SCH_ESP32-Ethernet-Kit_A_V1.2_20200528.pdf>`_,
    sheet 2, location D2.


RMII Clock Sourced Externally by PHY
""""""""""""""""""""""""""""""""""""

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.

.. figure:: img/esp32-ethernet-kit-rmii-clk-from-phy.jpg
    :align: center
    :alt: RMII Clock from IP101GRI PHY
    :figclass: align-center

    RMII Clock from IP101GRI PHY

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).


RMII Clock Sourced Internally from ESP32's APLL
"""""""""""""""""""""""""""""""""""""""""""""""

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.

.. figure:: img/esp32-ethernet-kit-rmii-clk-to-phy.jpg
    :align: center
    :alt: RMII Clock from ESP Internal APLL
    :figclass: align-center

    RMII Clock from ESP Internal APLL

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 <https://dl.espressif.com/dl/schematics/SCH_ESP32-Ethernet-Kit_A_V1.2_20200528.pdf>`_,
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.


GPIO Allocation
---------------

This section describes allocation of ESP32 GPIOs to specific interfaces or
functions of the ESP32-Ethernet-Kit.


IP101GRI (PHY) Interface
^^^^^^^^^^^^^^^^^^^^^^^^

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).

====  ================  ===============
No.   ESP32 Pin (MAC)   IP101GRI (PHY)
====  ================  ===============
*RMII Interface*
---------------------------------------
 1    GPIO21            TX_EN
 2    GPIO19            TXD[0]
 3    GPIO22            TXD[1]
 4    GPIO25            RXD[0]
 5    GPIO26            RXD[1]
 6    GPIO27            CRS_DV
 7    GPIO0             REF_CLK
----  ----------------  ---------------
*Serial Management Interface*
---------------------------------------
 8    GPIO23            MDC
 9    GPIO18            MDIO
----  ----------------  ---------------
*PHY Reset*
---------------------------------------
10    GPIO5             Reset_N
====  ================  ===============

.. note::

    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.


GPIO Header 1
^^^^^^^^^^^^^

This header exposes some GPIOs that are not used elsewhere on the
ESP32-Ethernet-Kit.

====  ================
No.   ESP32 Pin
====  ================
 1    GPIO32
 2    GPIO33
 3    GPIO34
 4    GPIO35
 5    GPIO36
 6    GPIO39
====  ================


GPIO Header 2
^^^^^^^^^^^^^

This header contains GPIOs that may be used for other purposes depending on
scenarios described in column "Comments".

====  ==========  ====================
No.   ESP32 Pin   Comments
====  ==========  ====================
 1    GPIO17      See note 1
 2    GPIO16      See note 1
 3    GPIO4
 4    GPIO2
 5    GPIO13      See note 2
 6    GPIO12      See note 2
 7    GPIO15      See note 2
 8    GPIO14      See note 2
 9    GND         Ground
10    3V3         3.3 V power supply
====  ==========  ====================

.. note::

    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.

    2. Functionality depends on the settings of the `Function Switch`_.


GPIO Allocation Summary
^^^^^^^^^^^^^^^^^^^^^^^

.. csv-table::
    :header: ESP32-WROVER-E,IP101GRI,UART,JTAG,GPIO,Comments

    S_VP,,,,IO36,
    S_VN,,,,IO39,
    IO34,,,,IO34,
    IO35,,,,IO35,
    IO32,,,,IO32,
    IO33,,,,IO33,
    IO25,RXD[0],,,,
    IO26,RXD[1],,,,
    IO27,CRS_DV,,,,
    IO14,,,TMS,IO14,
    IO12,,,TDI,IO12,
    IO13,,,TCK,IO13,
    IO15,,,TDO,IO15,
    IO2,,,,IO2,
    IO0,REF_CLK,,,,See note 1
    IO4,,,,IO4,
    IO16,,,,IO16 (NC),See note 2
    IO17,,,,IO17 (NC),See note 2
    IO5,Reset_N,,,,See note 1
    IO18,MDIO,,,,
    IO19,TXD[0],,,,
    IO21,TX_EN,,,,
    RXD0,,RXD,,,
    TXD0,,TXD,,,
    IO22,TXD[1],,,,
    IO23,MDC,,,,

.. note::

    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 <https://dl.espressif.com/dl/schematics/SCH_ESP32-Ethernet-Kit_A_V1.2_20200528.pdf>`_.

    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.

System requirements
-------------------

Prerequisites
-------------

Espressif HAL requires WiFi and Bluetooth binary blobs in order work. Run the command
below to retrieve those files.

.. code-block:: console

   west blobs fetch hal_espressif

.. note::

   It is recommended running the command above after :file:`west update`.

Building & Flashing
-------------------

Build and flash applications as usual (see :ref:`build_an_application` and
:ref:`application_run` for more details).

.. zephyr-app-commands::
   :zephyr-app: samples/hello_world
   :board: esp32_ethernet_kit
   :goals: build

The usual ``flash`` target will work with the ``esp32_ethernet_kit`` board
configuration. Here is an example for the :ref:`hello_world`
application.

.. zephyr-app-commands::
   :zephyr-app: samples/hello_world
   :board: esp32_ethernet_kit
   :goals: flash

Open the serial monitor using the following command:

.. code-block:: shell

   west espressif monitor

After the board has automatically reset and booted, you should see the following
message in the monitor:

.. code-block:: console

   ***** Booting Zephyr OS vx.x.x-xxx-gxxxxxxxxxxxx *****
   Hello World! esp32_ethernet_kit

Debugging
---------

As with much custom hardware, the ESP32 modules require patches to
OpenOCD that are not upstreamed yet. Espressif maintains their own fork of
the project. The custom OpenOCD can be obtained at `OpenOCD ESP32`_

The Zephyr SDK uses a bundled version of OpenOCD by default. You can overwrite that behavior by adding the
``-DOPENOCD=<path/to/bin/openocd> -DOPENOCD_DEFAULT_PATH=<path/to/openocd/share/openocd/scripts>``
parameter when building.

Here is an example for building the :ref:`hello_world` application.

.. zephyr-app-commands::
   :zephyr-app: samples/hello_world
   :board: esp32_ethernet_kit
   :goals: build flash
   :gen-args: -DOPENOCD=<path/to/bin/openocd> -DOPENOCD_DEFAULT_PATH=<path/to/openocd/share/openocd/scripts>

You can debug an application in the usual way. Here is an example for the :ref:`hello_world` application.

.. zephyr-app-commands::
   :zephyr-app: samples/hello_world
   :board: esp32_ethernet_kit
   :goals: debug


Enabling Ethernet
-----------------

Enable Ethernet MAC, PHY and MDIO; add these to your device tree overlay::

    &eth {
        status = "okay";
    };

    &phy {
        status = "okay";
    };

    &mdio {
        status = "okay";
    };

Enable Ethernet in KConfig::

    CONFIG_ETH_ESP32=y
    CONFIG_NETWORKING=y
    CONFIG_NET_L2_ETHERNET=y

Board Init
-----------------

RESET_N (GPIO5) is automatically set high to enable the Ethernet PHY
during board initialization (board_init.c)

Related Documents
-----------------

* `ESP32-Ethernet-Kit V1.2 Ethernet Board (A) Schematic <https://dl.espressif.com/dl/schematics/SCH_ESP32-Ethernet-Kit_A_V1.2_20200528.pdf>`_ (PDF)
* `ESP32-Ethernet-Kit PoE Board (B) Schematic <https://dl.espressif.com/dl/schematics/SCH_ESP32-ETHERNET-KIT_B_V1.0_20190517.pdf>`_ (PDF)
* `ESP32-Ethernet-Kit V1.2 Ethernet Board (A) PCB Layout <https://dl.espressif.com/dl/schematics/PCB_ESP32-Ethernet-Kit_A_V1_2_20190829.pdf>`_ (PDF)
* `ESP32-Ethernet-Kit PoE Board (B) PCB Layout <https://dl.espressif.com/dl/schematics/PCB_ESP32-Ethernet-Kit_B_V1_0_20190306.pdf>`_ (PDF)
* `ESP32 Datasheet <https://www.espressif.com/sites/default/files/documentation/esp32_datasheet_en.pdf>`_ (PDF)
* `ESP32-WROVER-E Datasheet <https://www.espressif.com/sites/default/files/documentation/esp32-wrover-e_esp32-wrover-ie_datasheet_en.pdf>`_ (PDF)
* `OpenOCD ESP32 <https://github.com/espressif/openocd-esp32/releases>`_