# Build the Project

Build the project by running:

    idf.py build

This command compiles the application and all ESP-IDF components, then it generates the bootloader, partition table, and application binaries.

    $ idf.py build
    Running cmake in directory /path/to/hello_world/build
    Executing "cmake -G Ninja --warn-uninitialized /path/to/hello_world"...
    Warn about uninitialized values.
    -- Found Git: /usr/bin/git (found version "2.17.0")
    -- Building empty aws_iot component due to configuration
    -- Component names: ...
    -- Component paths: ...

    ... (more lines of build system output)

    [527/527] Generating hello_world.bin
    esptool v5.0.2

    Project build complete. To flash, run:
      idf.py flash
    or
      idf.py -p PORT flash
    or
      esptool -p (PORT) -b 921600 write-flash --flash-mode dio --flash-size detect --flash-freq 40m 0x10000 build/hello_world.bin  build 0x1000 build/bootloader/bootloader.bin 0x8000 build/partition_table/partition-table.bin

If there are no errors, the build finishes by generating the firmware binary .bin files.

# Flash onto the Device

To flash the binaries that you just built for the ESP32-S31 in the previous step, you need to run the following command:

    idf.py -p PORT flash

Replace `PORT` with your ESP32-S31 board's USB port name. If the `PORT` is not defined, the idf.py will try to connect automatically using the available USB ports.

For more information on `idf.py` arguments, see idf.py.

Note

The option `flash` automatically builds and flashes the project, so running `idf.py build` is not necessary.

Encountered Issues While Flashing? See the "Additional Tips" below. You can also refer to Flashing Troubleshooting page or Establish Serial Connection with ESP32-S31 for more detailed information.

## Normal Operation

When flashing, you will see the output log similar to the following:

    ...
    esptool --chip esp32s31 -p /dev/ttyUSB0 -b 460800 --before=default-reset --after=hard-reset write-flash --flash-mode dio --flash-freq 80m --flash-size 2MB 0x0 bootloader/bootloader.bin 0x8000 partition_table/partition-table.bin 0x10000 hello_world.bin
    esptool v5.0.2
    Connected to ESP32-S31 on /dev/ttyUSB0:
    Chip type:          ESP32-S31 (revision v0.0)
    Features:           Wi-Fi, BT 5 (LE), IEEE802.15.4, Dual Core, 240MHz, Embedded PSRAM
    Crystal frequency:  40MHz
    MAC:                f4:12:fa:87:c6:dc

    Stub flasher running.
    Changing baud rate to 460800...
    Changed.

    Configuring flash size...
    Flash will be erased from 0x00000000 to 0x00005fff...
    Flash will be erased from 0x00008000 to 0x00008fff...
    Flash will be erased from 0x00010000 to 0x00037fff...
    SHA digest in image updated.
    Wrote 21280 bytes (13578 compressed) at 0x00000000 in 0.6 seconds (298.1 kbit/s).
    Hash of data verified.
    Wrote 3072 bytes (103 compressed) at 0x00008000 in 0.1 seconds (315.1 kbit/s).
    Hash of data verified.
    Wrote 161744 bytes (90141 compressed) at 0x00010000 in 2.5 seconds (513.7 kbit/s).
    Hash of data verified.

    Hard resetting via RTS pin...

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 would like to use the Eclipse or VS Code IDE instead of running `idf.py`, check out Eclipse Plugin, VSCode Extension.

# 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 IDF Monitor application.

    $ idf.py -p <PORT> monitor
    Running idf_monitor in directory [...]/esp/hello_world/build
    Executing "python [...]/esp-idf/tools/idf_monitor.py -b 115200 [...]/esp/hello_world/build/hello_world.elf"...
    --- idf_monitor on <PORT> 115200 ---
    --- Quit: Ctrl+] | Menu: Ctrl+T | Help: Ctrl+T followed by Ctrl+H ---
    ets Jun  8 2016 00:22:57

    rst:0x1 (POWERON_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
    ets Jun  8 2016 00:22:57
    ...

After startup and diagnostic logs scroll up, you should see "Hello world!" printed out by the application.

        ...
        Hello world!
        Restarting in 10 seconds...
        This is esp32s31 chip with 2 CPU core(s), [NEEDS TO BE UPDATED]
    Minimum free heap size: [NEEDS TO BE UPDATED] bytes
        Restarting in 9 seconds...
        Restarting in 8 seconds...
        Restarting in 7 seconds...

To exit IDF monitor use the shortcut `Ctrl+]`.

Note

You can combine building, flashing and monitoring into one step by running:

    idf.py -p PORT flash monitor

See also:

- IDF Monitor for handy shortcuts and more details on using IDF monitor.

- idf.py for a full reference of `idf.py` commands and options.

That is all that you need to get started with ESP32-S31!

Now you are ready to try some other examples, or go straight to developing your own applications.

Important

Some of examples do not support ESP32-S31 because required hardware is not included in ESP32-S31 so it cannot be supported.

If building an example, please check the README file for the `Supported Targets` table. If this is present including ESP32-S31 target, or the table does not exist at all, the example will work on ESP32-S31.

# Additional Tips

## Permission Denied Issue

With some Linux distributions, you may get the error message similar to `Could not open port <PORT>: Permission denied: '<PORT>'` when flashing the ESP32-S31. This can be solved by adding the current user to the specific group, such as `dialout` or `uucp` group.

## Python Compatibility

ESP-IDF supports Python 3.10 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 or the use of a Python version management system such as pyenv.

## Flash Erase

Erasing the flash is also possible. To erase the entire flash memory you can run the following command:

    idf.py -p PORT erase-flash

For erasing the OTA data, if present, you can run this command:

    idf.py -p PORT erase-otadata

The flash erase command can take a while to be done. Do not disconnect your device while the flash erasing is in progress.

# Related Documents

- Establish Serial Connection with ESP32-S31

- IDF Monitor

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