.. _esp32_devkitc_wroom:

ESP32-DEVKITC-WROOM
###################

Overview
********

ESP32-DEVKITC-WROOM is a series of low cost, low power system on a chip microcontrollers
with integrated Wi-Fi & dual-mode Bluetooth.  The ESP32 series employs a
Tensilica Xtensa LX6 microprocessor in both dual-core and single-core
variations.  ESP32-WROOM is created and developed by Espressif Systems, a
Shanghai-based Chinese company, and is manufactured by TSMC using their 40nm
process. [1]_

The features include the following:

- Dual core Xtensa microprocessor (LX6), running at 160 or 240MHz
- 520KB of SRAM
- 802.11b/g/n/e/i
- Bluetooth v4.2 BR/EDR and BLE
- Various peripherals:

  - 12-bit ADC with up to 18 channels
  - 2x 8-bit DACs
  - 10x touch sensors
  - Temperature sensor
  - 4x SPI
  - 2x I2S
  - 2x I2C
  - 3x UART
  - SD/SDIO/MMC host
  - Slave (SDIO/SPI)
  - Ethernet MAC
  - CAN bus 2.0
  - IR (RX/TX)
  - Motor PWM
  - LED PWM with up to 16 channels
  - Hall effect sensor

- Cryptographic hardware acceleration (RNG, ECC, RSA, SHA-2, AES)
- 5uA deep sleep current

.. figure:: img/esp32_devkitc_wroom.jpg
    :align: center
    :alt: ESP32-DEVKITC-WROOM

    ESP32-DevKitC-WROOM-32D DK

Asymmetric Multiprocessing (AMP)
********************************

ESP32-DEVKITC-WROOM allows 2 different applications to be executed in ESP32 SoC. Due to its dual-core architecture, each core can be enabled to execute customized tasks in stand-alone mode
and/or exchanging data over OpenAMP framework. See :ref:`ipc_samples` folder as code reference.

Supported Features
==================

Current Zephyr's ESP32-WROOM board supports the following features:

+------------+------------+-------------------------------------+
| Interface  | Controller | Driver/Component                    |
+============+============+=====================================+
+------------+------------+-------------------------------------+
| UART       | on-chip    | serial port                         |
+------------+------------+-------------------------------------+
| GPIO       | on-chip    | gpio                                |
+------------+------------+-------------------------------------+
| PINMUX     | on-chip    | pinmux                              |
+------------+------------+-------------------------------------+
| USB-JTAG   | on-chip    | hardware interface                  |
+------------+------------+-------------------------------------+
| SPI Master | on-chip    | spi                                 |
+------------+------------+-------------------------------------+
| Timers     | on-chip    | counter                             |
+------------+------------+-------------------------------------+
| Watchdog   | on-chip    | watchdog                            |
+------------+------------+-------------------------------------+
| TRNG       | on-chip    | entropy                             |
+------------+------------+-------------------------------------+
| LEDC       | on-chip    | pwm                                 |
+------------+------------+-------------------------------------+
| MCPWM      | on-chip    | pwm                                 |
+------------+------------+-------------------------------------+
| PCNT       | on-chip    | qdec                                |
+------------+------------+-------------------------------------+
| SPI DMA    | on-chip    | spi                                 |
+------------+------------+-------------------------------------+
| TWAI       | on-chip    | can                                 |
+------------+------------+-------------------------------------+
| ADC        | on-chip    | adc                                 |
+------------+------------+-------------------------------------+
| DAC        | on-chip    | dac                                 |
+------------+------------+-------------------------------------+
| Wi-Fi      | on-chip    |                                     |
+------------+------------+-------------------------------------+
| Bluetooth  | on-chip    |                                     |
+------------+------------+-------------------------------------+

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_devkitc_wroom
   :goals: build

The usual ``flash`` target will work with the ``esp32_devkitc_wroom`` board
configuration. Here is an example for the :ref:`hello_world`
application.

.. zephyr-app-commands::
   :zephyr-app: samples/hello_world
   :board: esp32_devkitc_wroom
   :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_devkitc_wroom

Debugging
---------

ESP32-DEVKITC-WROOM support on OpenOCD is available upstream as of version 0.12.0.
Download and install OpenOCD from `OpenOCD`_.

On the ESP-WROOM-32 DevKitC board, the JTAG pins are not run to a
standard connector (e.g. ARM 20-pin) and need to be manually connected
to the external programmer (e.g. a Flyswatter2):

+------------+-----------+
| ESP32 pin  | JTAG pin  |
+============+===========+
| 3V3        | VTRef     |
+------------+-----------+
| EN         | nTRST     |
+------------+-----------+
| IO14       | TMS       |
+------------+-----------+
| IO12       | TDI       |
+------------+-----------+
| GND        | GND       |
+------------+-----------+
| IO13       | TCK       |
+------------+-----------+
| IO15       | TDO       |
+------------+-----------+

Further documentation can be obtained from the SoC vendor in `JTAG debugging
for ESP32`_.

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

.. zephyr-app-commands::
   :zephyr-app: samples/hello_world
   :board: esp32_devkitc_wroom
   :goals: build flash

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_devkitc_wroom
   :goals: debug

Note on Debugging with GDB Stub
===============================

GDB stub is enabled on ESP32.

* When adding breakpoints, please use hardware breakpoints with command
  ``hbreak``. Command ``break`` uses software breakpoints which requires
  modifying memory content to insert break/trap instructions.
  This does not work as the code is on flash which cannot be randomly
  accessed for modification.

.. _`JTAG debugging for ESP32`: https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-guides/jtag-debugging/index.html
.. _`OpenOCD`: https://github.com/openocd-org/openocd

References
**********

.. [1] https://en.wikipedia.org/wiki/ESP32
.. _ESP32 Technical Reference Manual: https://espressif.com/sites/default/files/documentation/esp32_technical_reference_manual_en.pdf
.. _Hardware Reference: https://docs.espressif.com/projects/esp-idf/en/latest/esp32/hw-reference/index.html