JTAG Debugging
==============
:link_to_translation:`zh_CN:[中文]`

This document provides a guide to installing OpenOCD for {IDF_TARGET_NAME} and debugging using GDB. The document is structured as follows:

:ref:`jtag-debugging-introduction`
    Introduction to the purpose of this guide.
:ref:`jtag-debugging-how-it-works`
    Description how {IDF_TARGET_NAME}, JTAG interface, OpenOCD and GDB are interconnected and working together to enable debugging of {IDF_TARGET_NAME}.
:ref:`jtag-debugging-selecting-jtag-adapter`
    What are the criteria and options to select JTAG adapter hardware.
:ref:`jtag-debugging-setup-openocd`
    Procedure to install OpenOCD and verify that it is installed.
:ref:`jtag-debugging-configuring-target`
    Configuration of OpenOCD software and setting up of JTAG adapter hardware, which together make up the debugging target.
:ref:`jtag-debugging-launching-debugger`
    Steps to start up a debug session with GDB from :ref:`jtag-debugging-using-debugger-eclipse` and from :ref:`jtag-debugging-using-debugger-command-line`.
:ref:`jtag-debugging-examples`
    If you are not familiar with GDB, check this section for debugging examples provided from :ref:`jtag-debugging-examples-eclipse` as well as from :ref:`jtag-debugging-examples-command-line`.
:ref:`jtag-debugging-building-openocd`
    Procedure to build OpenOCD from sources for :doc:`Windows <building-openocd-windows>`, :doc:`Linux <building-openocd-linux>` and :doc:`macOS <building-openocd-macos>` operating systems.
:ref:`jtag-debugging-tips-and-quirks`
    This section provides collection of tips and quirks related to JTAG debugging of {IDF_TARGET_NAME} with OpenOCD and GDB.


.. include:: {IDF_TARGET_PATH_NAME}.inc
   :start-after: devkit-defs
   :end-before: ---


.. _jtag-debugging-introduction:

Introduction
------------

.. only:: esp32

    The ESP32 has two powerful Xtensa cores, allowing for a great deal of variety of program architectures. The FreeRTOS OS that comes with ESP-IDF is capable of multi-core preemptive scheduling, allowing for an intuitive way of writing software.

    The downside of the ease of programming is that debugging without the right tools is harder: figuring out a bug that is caused by two threads, running even simultaneously on two different CPU cores, can take a long time when all you have are ``printf()`` statements. A better (and in many cases quicker) way to debug such problems is by using a debugger, connected to the processors over a debug port.

Espressif has ported OpenOCD to support the {IDF_TARGET_NAME} processor and the multi-core FreeRTOS （which is the foundation of most {IDF_TARGET_NAME} apps). Additionally, some extra tools have been written to provide extra features that OpenOCD does not support natively.

This document provides a guide to installing OpenOCD for {IDF_TARGET_NAME} and debugging using GDB under Linux, Windows and macOS. Except for OS specific installation procedures, the s/w user interface and use procedures are the same across all supported operating systems.

.. note::

    Screenshots presented in this document have been made for Eclipse Neon 3 running on Ubuntu 16.04 LTS. There may be some small differences in what a particular user interface looks like, depending on whether you are using Windows, macOS or Linux and / or a different release of Eclipse.

.. _jtag-debugging-how-it-works:

How it Works?
-------------

The key software and hardware components that perform debugging of {IDF_TARGET_NAME} with OpenOCD over JTAG (Joint Test Action Group) interface is presented in the diagram below under the "Debugging With JTAG" label. These components include {IDF_TARGET_TOOLCHAIN_PREFIX}-gdb debugger, OpenOCD on chip debugger, and the JTAG adapter connected to {IDF_TARGET_NAME} target.

.. figure:: ../../../_static/jtag-debugging-overview.jpg
    :align: center
    :alt: JTAG debugging - overview diagram
    :figclass: align-center

    JTAG debugging - overview diagram

Likewise, the "Application Loading and Monitoring" label indicates the key software and hardware components that allow an application to be compiled, built, and flashed to {IDF_TARGET_NAME}, as well as to provide means to monitor diagnostic messages from {IDF_TARGET_NAME}.

"Debugging With JTAG" and "Application Loading and Monitoring" is integrated under the `Eclipse <https://www.eclipse.org/>`_ IDE in order to provide a quick and easy transition between writing/compiling/loading/debugging code. The Eclipse IDE (and the integrated debugging software) is available for Windows, Linux and macOS platforms. Depending on user preferences, both the debugger and ``idf.py build`` can also be used directly from terminal/command line, instead of Eclipse.

.. only:: esp32 or esp32s2

    If the |devkit-name-with-link| is used, then connection from PC to {IDF_TARGET_NAME} is done effectively with a single USB cable. This is made possible by the FT2232H chip, which provides two USB channels, one for JTAG and the other for UART connection.

.. only:: SOC_USB_SERIAL_JTAG_SUPPORTED

    The connection from PC to {IDF_TARGET_NAME} is done effectively with a single USB cable. This is made possible by the {IDF_TARGET_NAME} chip itself, which provides two USB channels, one for JTAG and the other for the USB terminal connection. The USB cable should be connected to the D+/D- USB pins of {IDF_TARGET_NAME} and not to the serial RxD/TxD through a USB-to-UART chip. The proper connection is explained later in subsection :ref:`jtag-debugging-configuring-target`.

.. only:: esp32c3

    .. note::

        Debugging through the USB interface implemented in {IDF_TARGET_NAME} requires to have a chip with revision 3 or newer. Please use other debugging options (e.g. with ESP-Prog) for chip revision 1 and 2. The easiest way to determine the chip revision is to look for the ``Chip is ESP32-C3 (revision 3)`` message near the end of a successful chip flashing done by ``idf.py flash``.

.. _jtag-debugging-selecting-jtag-adapter:

Selecting JTAG Adapter
----------------------

.. only:: esp32 or esp32s2

    The quickest and most convenient way to start with JTAG debugging is by using |devkit-name-with-link|. Each version of this development board has JTAG interface already built in. No need for an external JTAG adapter and extra wiring / cable to connect JTAG to {IDF_TARGET_NAME}. |devkit-name| is using FT2232H JTAG interface operating at 20 MHz clock speed, which is difficult to achieve with an external adapter.

.. only:: SOC_USB_SERIAL_JTAG_SUPPORTED

    The quickest and most convenient way to start with JTAG debugging is through a USB cable connected to the D+/D- USB pins of {IDF_TARGET_NAME}. No need for an external JTAG adapter and extra wiring / cable to connect JTAG to {IDF_TARGET_NAME}.

If you decide to use separate JTAG adapter, look for one that is compatible with both the voltage levels on the {IDF_TARGET_NAME} as well as with the OpenOCD software. The JTAG port on the {IDF_TARGET_NAME} is an industry-standard JTAG port which lacks (and does not need) the TRST pin. The JTAG I/O pins all are powered from the VDD_3P3_RTC pin (which normally would be powered by a 3.3 V rail) so the JTAG adapter needs to be able to work with JTAG pins in that voltage range.

On the software side, OpenOCD supports a fair amount of JTAG adapters. See https://openocd.org/doc/html/Debug-Adapter-Hardware.html for an (unfortunately slightly incomplete) list of the adapters OpenOCD works with. This page lists SWD-compatible adapters as well; take note that the {IDF_TARGET_NAME} does not support SWD. JTAG adapters that are hardcoded to a specific product line, e.g. ST-LINK debugging adapters for STM32 families, will not work.

The minimal signalling to get a working JTAG connection are TDI, TDO, TCK, TMS and GND. Some JTAG debuggers also need a connection from the {IDF_TARGET_NAME} power line to a line called e.g. Vtar to set the working voltage. SRST can optionally be connected to the CH_PD of the {IDF_TARGET_NAME}, although for now, support in OpenOCD for that line is pretty minimal.

`ESP-Prog <https://docs.espressif.com/projects/espressif-esp-iot-solution/en/latest/hw-reference/ESP-Prog_guide.html>`_ is an example for using an external board for debugging by connecting it to the JTAG pins of {IDF_TARGET_NAME}.

.. _jtag-debugging-setup-openocd:

Setup of OpenOCD
----------------

.. highlight:: bash

If you have already set up ESP-IDF with CMake build system according to the :doc:`Getting Started Guide <../../get-started/index>`, then OpenOCD is already installed. After :ref:`setting up the environment <get-started-set-up-env>` in your terminal, you should be able to run OpenOCD. Check this by executing the following command::

    openocd --version

.. highlight:: none

The output should be as follows (although the version may be more recent than listed here)::

    Open On-Chip Debugger  v0.10.0-esp32-20190708 (2019-07-08-11:04)
    Licensed under GNU GPL v2
    For bug reports, read
        https://openocd.org/doc/doxygen/bugs.html

You may also verify that OpenOCD knows where its configuration scripts are located by printing the value of ``OPENOCD_SCRIPTS`` environment variable, by typing ``echo $OPENOCD_SCRIPTS`` (for Linux and macOS) or ``echo %OPENOCD_SCRIPTS%`` (for Windows). If a valid path is printed, then OpenOCD is set up correctly.

If any of these steps do not work, please go back to the :ref:`setting up the tools <get-started-set-up-tools>` section of the Getting Started Guide.

.. note::

    It is also possible to build OpenOCD from source. Please refer to :ref:`jtag-debugging-building-openocd` section for details.

.. _jtag-debugging-configuring-target:

Configuring {IDF_TARGET_NAME} Target
-------------------------------------

Once OpenOCD is installed, you can proceed to configuring the {IDF_TARGET_NAME} target (i.e {IDF_TARGET_NAME} board with JTAG interface). Configuring the target is split into the following three steps:

* :ref:`jtag-debugging-configure-and-connect-JTAG-interface`
* :ref:`jtag-debugging-run-openocd`
* :ref:`jtag-upload-app-debug`

.. _jtag-debugging-configure-and-connect-JTAG-interface:

Configure and connect JTAG interface
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

This step depends on the JTAG and {IDF_TARGET_NAME} board you are using (see the two cases described below).

.. toctree::
    :maxdepth: 1

    :esp32: configure-ft2232h-jtag
    :esp32s2: configure-ft2232h-jtag
    :SOC_USB_SERIAL_JTAG_SUPPORTED: configure-builtin-jtag
    configure-other-jtag


.. _jtag-debugging-run-openocd:

Run OpenOCD
^^^^^^^^^^^

Once target is configured and connected to computer, you are ready to launch OpenOCD.

.. highlight:: bash

Open a terminal and set it up for using the ESP-IDF as described in the :ref:`setting up the environment <get-started-set-up-env>` section of the Getting Started Guide. Then run OpenOCD (this command works on Windows, Linux, and macOS):

.. include:: {IDF_TARGET_PATH_NAME}.inc
   :start-after: run-openocd
   :end-before: ---

.. note::

    The files provided after ``-f`` above are specific for |run-openocd-device-name|. You may need to provide different files depending on the hardware that is used. For guidance see :ref:`jtag-debugging-tip-openocd-configure-target`.

    .. only:: esp32c3

    For example, ``board/esp32c3-ftdi.cfg`` can be used for a custom board with an FT2232H or FT232H chip used for JTAG connection, or with ESP-Prog.

.. highlight:: none

You should now see similar output (this log is for |run-openocd-device-name|):

.. include:: {IDF_TARGET_PATH_NAME}.inc
   :start-after: run-openocd-output
   :end-before: ---

* If there is an error indicating permission problems, please see section on "Permissions delegation" in the OpenOCD README file located in the ``~/esp/openocd-esp32`` directory.
* In case there is an error in finding the configuration files, e.g. |run-openocd-cfg-file-err|, check if the ``OPENOCD_SCRIPTS`` environment variable is set correctly. This variable is used by OpenOCD to look for the files specified after the ``-f`` option. See :ref:`jtag-debugging-setup-openocd` section for details. Also check if the file is indeed under the provided path.
* If you see JTAG errors (e.g., ``...all ones`` or ``...all zeroes``), please check your JTAG connections, whether other signals are connected to JTAG besides {IDF_TARGET_NAME}'s pins, and see if everything is powered on correctly.

.. _jtag-upload-app-debug:

Upload application for debugging
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Build and upload your application to {IDF_TARGET_NAME} as usual, see :ref:`get-started-build`.

Another option is to write application image to flash using OpenOCD via JTAG with commands like this:

.. include:: {IDF_TARGET_PATH_NAME}.inc
   :start-after: run-openocd-upload
   :end-before: ---

OpenOCD flashing command ``program_esp`` has the following format:

``program_esp <image_file> <offset> [verify] [reset] [exit]``

 - ``image_file`` - Path to program image file.
 - ``offset`` - Offset in flash bank to write image.
 - ``verify`` - Optional. Verify flash contents after writing.
 - ``reset`` - Optional. Reset target after programing.
 - ``exit`` - Optional. Finally exit OpenOCD.

You are now ready to start application debugging. Follow the steps described in the section below.


.. _jtag-debugging-launching-debugger:

Launching Debugger
---------------------

The toolchain for {IDF_TARGET_NAME} features GNU Debugger, in short GDB. It is available with other toolchain programs under filename: {IDF_TARGET_TOOLCHAIN_PREFIX}-gdb. GDB can be called and operated directly from command line in a terminal. Another option is to call it from within IDE (like Eclipse, Visual Studio Code, etc.) and operate indirectly with help of GUI instead of typing commands in a terminal.

Both options of using debugger are discussed under links below.

* :ref:`jtag-debugging-using-debugger-eclipse`
* :ref:`jtag-debugging-using-debugger-command-line`

It is recommended to first check if debugger works from :ref:`jtag-debugging-using-debugger-command-line` and then move to using :ref:`jtag-debugging-using-debugger-eclipse`.


.. _jtag-debugging-examples:

Debugging Examples
----------------------

This section is intended for users not familiar with GDB. It presents example debugging session from :ref:`jtag-debugging-examples-eclipse` using simple application available under :example:`get-started/blink` and covers the following debugging actions:

1. :ref:`jtag-debugging-examples-eclipse-01`
2. :ref:`jtag-debugging-examples-eclipse-02`
3. :ref:`jtag-debugging-examples-eclipse-03`
4. :ref:`jtag-debugging-examples-eclipse-04`
5. :ref:`jtag-debugging-examples-eclipse-05`
6. :ref:`jtag-debugging-examples-eclipse-06`
7. :ref:`jtag-debugging-examples-eclipse-07`

Similar debugging actions are provided using GDB from :ref:`jtag-debugging-examples-command-line`.

Before proceeding to examples, set up your {IDF_TARGET_NAME} target and load it with :example:`get-started/blink`.


.. _jtag-debugging-building-openocd:

Building OpenOCD from Sources
---------------------------------

Please refer to separate documents listed below, that describe build process.

.. toctree::
    :maxdepth: 1

    Windows <building-openocd-windows>
    Linux <building-openocd-linux>
    macOS <building-openocd-macos>

The examples of invoking OpenOCD in this document assume using pre-built binary distribution described in section :ref:`jtag-debugging-setup-openocd`.

To use binaries build locally from sources, change the path to OpenOCD executable to ``src/openocd`` and set the ``OPENOCD_SCRIPTS`` environment variable so that OpenOCD can find the configuration files. For Linux and macOS:

.. code-block:: bash

    cd ~/esp/openocd-esp32
    export OPENOCD_SCRIPTS=$PWD/tcl

For Windows:

.. code-block:: batch

    cd %USERPROFILE%\esp\openocd-esp32
    set "OPENOCD_SCRIPTS=%CD%\tcl"

Example of invoking OpenOCD build locally from sources, for Linux and macOS:

.. include:: {IDF_TARGET_PATH_NAME}.inc
   :start-after: run-openocd-src-linux
   :end-before: ---

and Windows:

.. include:: {IDF_TARGET_PATH_NAME}.inc
   :start-after: run-openocd-src-win
   :end-before: ---

.. _jtag-debugging-tips-and-quirks:

Tips and Quirks
------------------

This section provides collection of links to all tips and quirks referred to from various parts of this guide.

.. toctree::
    :maxdepth: 2

    tips-and-quirks


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

.. toctree::
    :hidden:

    :maxdepth: 1

    using-debugger
    debugging-examples
    tips-and-quirks
    ../app_trace

- :doc:`using-debugger`
- :doc:`debugging-examples`
- :doc:`tips-and-quirks`
- :doc:`../app_trace`
- `Introduction to ESP-Prog Board <https://docs.espressif.com/projects/espressif-esp-iot-solution/en/latest/hw-reference/ESP-Prog_guide.html>`__
