If you run the given command and see errors such as "Failed to connect", there might be several reasons for this. One of the reasons might be issues encountered by ``esptool.py``, the utility that is called by the build system to reset the chip, interact with the ROM bootloader, and flash firmware. One simple solution to try is manual reset described below, and if it does not help you can find more details about possible issues in `Troubleshooting <https://github.com/espressif/esptool#bootloader-wont-respond>`_.
``esptool.py`` resets {IDF_TARGET_NAME} automatically by asserting DTR and RTS control lines of the USB to serial converter chip, i.e., FTDI or CP210x (for more information, see :doc:`establish-serial-connection`). The DTR and RTS control lines are in turn connected to ``{IDF_TARGET_STRAP_GPIO}`` and ``CHIP_PU`` (EN) pins of {IDF_TARGET_NAME}, thus changes in the voltage levels of DTR and RTS will boot {IDF_TARGET_NAME} into Firmware Download mode. As an example, check the `schematic <https://dl.espressif.com/dl/schematics/esp32_devkitc_v4-sch-20180607a.pdf>`_ for the ESP32 DevKitC development board.
In general, you should have no problems with the `official esp-idf development boards <https://www.espressif.com/en/products/devkits>`_. However, ``esptool.py`` is not able to reset your hardware automatically in the following cases:
- Your hardware does not have the DTR and RTS lines connected to ``{IDF_TARGET_STRAP_GPIO}`` and ``CHIP_PU``
- The DTR and RTS lines are configured differently
- There are no such serial control lines at all
Depending on the kind of hardware you have, it may also be possible to manually put your {IDF_TARGET_NAME} board into Firmware Download mode (reset).
- For development boards produced by Espressif, this information can be found in the respective getting started guides or user guides. For example, to manually reset an ESP-IDF development board, hold down the **Boot** button (``{IDF_TARGET_STRAP_GPIO}``) and press the **EN** button (``CHIP_PU``).
Wrote 3072 bytes (103 compressed) at 0x00008000 in 0.0 seconds (effective 4238.1 kbit/s)...
Hash of data verified.
Compressed 18960 bytes to 11311...
Writing at 0x00000000... (100 %)
Wrote 18960 bytes (11311 compressed) at 0x00000000 in 0.3 seconds (effective 584.9 kbit/s)...
Hash of data verified.
Compressed 145520 bytes to 71984...
Writing at 0x00010000... (20 %)
Writing at 0x00014000... (40 %)
Writing at 0x00018000... (60 %)
Writing at 0x0001c000... (80 %)
Writing at 0x00020000... (100 %)
Wrote 145520 bytes (71984 compressed) at 0x00010000 in 2.3 seconds (effective 504.4 kbit/s)...
Hash of data verified.
Leaving...
Hard resetting via RTS pin...
Done
If there are no issues by the end of the flash process, the board will reboot and start up the “hello_world” application.
If you'd like to use the Eclipse or VS Code IDE instead of running ``idf.py``, check out the :doc:`Eclipse guide <eclipse-setup>`, :doc:`VS Code guide <vscode-setup>`.
Monitor the Output
==================
To check if "hello_world" is indeed running, type ``idf.py -p PORT monitor`` (Do not forget to replace PORT with your serial port name).
This command launches the :doc:`IDF Monitor <../api-guides/tools/idf-monitor>` application::
$ idf.py -p <PORT> monitor
Running idf_monitor in directory [...]/esp/hello_world/build
If IDF monitor fails shortly after the upload, or, if instead of the messages above, you see random garbage similar to what is given below, your board is likely using a 26 MHz crystal. Most development board designs use 40 MHz, so ESP-IDF uses this frequency as a default value.
3. Go to Component config --> ESP32-specific --> Main XTAL frequency, then change :ref:`CONFIG_ESP32_XTAL_FREQ_SEL` to 26 MHz.
4. After that, `build and flash` the application again.
..note::
You can combine building, flashing and monitoring into one step by running::
idf.py -p PORT flash monitor
See also:
-:doc:`IDF Monitor <../api-guides/tools/idf-monitor>` for handy shortcuts and more details on using IDF monitor.
-:ref:`idf.py` for a full reference of ``idf.py`` commands and options.
**That's all that you need to get started with {IDF_TARGET_NAME}!**
Now you are ready to try some other :idf:`examples`, or go straight to developing your own applications.
..important::
Some of examples do not support {IDF_TARGET_NAME} because required hardware is not included in {IDF_TARGET_NAME} so it cannot be supported.
If building an example, please check the README file for the ``Supported Targets`` table. If this is present including {IDF_TARGET_NAME} target, or the table does not exist at all, the example will work on {IDF_TARGET_NAME}.
Additional Tips
===============
Permission issues /dev/ttyUSB0
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
With some Linux distributions, you may get the ``Failed to open port /dev/ttyUSB0`` error message when flashing the {IDF_TARGET_NAME}. :ref:`This can be solved by adding the current user to the dialout group<linux-dialout-group>`.
ESP-IDF supports Python 3.7 or newer. It is recommended to upgrade your operating system to a recent version satisfying this requirement. Other options include the installation of Python from `sources <https://www.python.org/downloads/>`_ or the use of a Python version management system such as `pyenv <https://github.com/pyenv/pyenv>`_.
