RIOT/boards/esp32-ethernet-kit-v1_0/doc_common.txt

/*
 * Copyright (C) 2018 Gunar Schorcht
 * Copyright (C) 2020 Google LLC
 *
 * This file is subject to the terms and conditions of the GNU Lesser
 * General Public License v2.1. See the file LICENSE in the top level
 * directory for more details.
 */

/**
 * @defgroup    boards_esp32_esp-ethernet-kit ESP32-Ethernet-Kit
 * @ingroup     boards_esp32
 * @brief       Support for for Espressif ESP32-Ethernet-Kit
 * @author      Gunar Schorcht <gunar@schorcht.net>
 * @author      Erik Ekman <eekman@google.com>

## <a name="toc"> Table of Contents </a>

1. [Overview](#overview)
2. [Hardware](#hardware)
    1. [MCU](#mcu)
    2. [Board Configuration](#common_board_configuration)
3. [Flashing the Device](#flashing)
4. [On-Chip Debugging with the device](#debugging)

## <a name="overview"> Overview </a> &nbsp;&nbsp; [[TOC](#toc)]

The Espressif [ESP32-Ethernet-Kit](https://docs.espressif.com/projects/esp-idf/en/latest/esp32/hw-reference/esp32/get-started-ethernet-kit.html) is a development board that uses a ESP32-WROVER module (-B or -E depending on version). Most important features of the board are

- 100 Mbps Ethernet via IP101G PHY
- USB bridge with JTAG interface

Furthermore, some GPIOs are broken out for extension. The USB bridge based on FDI FT2232HL provides a JTAG interface for OCD debugging through the USB interface.

There are different revisions of the board:
- \ref boards_esp32_esp-ethernet-kit-v1_0
- \ref boards_esp32_esp-ethernet-kit-v1_1
- \ref boards_esp32_esp-ethernet-kit-v1_2

## <a name="hardware"> Hardware </a> &nbsp;&nbsp; [[TOC](#toc)]

This section describes

- the [MCU](#mcu),
- the default [board configuration](#common_board_configuration).

### <a name="mcu"> MCU </a> &nbsp;&nbsp; [[TOC](#toc)]

Most features of the board are provided by the ESP32 SoC. For detailed
information about the ESP32, see section \ref esp32_mcu "MCU ESP32".

### <a name="common_board_configuration"> Board Configuration </a> &nbsp;&nbsp; [[TOC](#toc)]

ESP32-Ethernet-Kit has the following on-board components

- 100 Mbps Ethernet via IP101G PHY
- USB bridge with JTAG interface

For detailed information about the configuration of ESP32 boards, see
section Peripherals in \ref esp32_riot.

The board is available in different versions. See the per-version file for details.

## <a name="flashing"> Flashing the Device </a> &nbsp;&nbsp; [[TOC](#toc)]

Flashing RIOT is quite straight forward. The board has a Micro-USB connector with reset/boot/flash logic. Just connect the board using the programming port to your host computer and type:
```
make flash BOARD=esp32-ethernet-kit-v1_X ...
```
where `X` is the minor revision number of the board.

The USB bridge is based on FDI FT2232HL and offers two USB interfaces:

- the first interface is the JTAG interface for [On-Chip debugging](#debugging)
- the second interface is the console interface, which is also used for flashing

Therefore, it might be necessary have to declare the USB interface in the make command. For example, if the ESP32-Ethernet-Kit is connected to the host computer through the USB interfaces `/dev/ttyUSB0` and `/dev/ttyUSB1`, the make command would be used as following:
```
make flash BOARD=esp32-ethernet-kit-v1_X PORT=/dev/ttyUSB1 ...
```
Please note that `/dev/ttyUSB1` is used as the console port by default. Therefore the variable `PORT` only needs to be defined if the console port is another port.

For detailed information about ESP32 as well as configuring and compiling RIOT for ESP32 boards, see \ref esp32_riot.

## <a name="debugging"> On-Chip Debugging with the Device </a> &nbsp;&nbsp; [[TOC](#toc)]

Since the USB bridge based on FDI FT2232HL provides a JTAG interface for debugging through an USB interface, using ESP32-Ethernet-Kit is the easiest and most convenient way for On-Chip debugging. Please refer the [ESP-IDF Programming Guide](https://docs.espressif.com/projects/esp-idf/en/latest/api-guides/jtag-debugging/index.html) for details on how to setup and how to use ESP32-Ethernet-Kit and OpenOCD.

To use the JTAG interface, the `esp_jtag` module must be used to disable the `SPI_DEV(0)` which normally uses the GPIOs for the JTAG signals.
USEMODULE=esp_jtag make flash BOARD=esp32-ethernet-kit-v1_X ...
Furthermore the function switches (DIP switches) for the JTAG signals must be set to ON.

 */