This is the documentation for the latest (main) development branch of Zephyr. If you are looking for the documentation of previous releases, use the drop-down menu on the left and select the desired version.

ESP32-S2 Franzininho


Franzininho is an educational development board based on ESP32-S2 which is a highly integrated, low-power, single-core Wi-Fi Microcontroller SoC, designed to be secure and cost-effective, with a high performance and a rich set of IO capabilities. [1]

The features include the following:

  • RSA-3072-based secure boot

  • AES-XTS-256-based flash encryption

  • Protected private key and device secrets from software access

  • Cryptographic accelerators for enhanced performance

  • Protection against physical fault injection attacks

  • Various peripherals:

    • 43x programmable GPIOs

    • 14x configurable capacitive touch GPIOs

    • USB OTG

    • LCD interface

    • camera interface

    • SPI

    • I2S

    • UART

    • ADC

    • DAC

    • LED PWM with up to 8 channels


System requirements


Espressif HAL requires WiFi and Bluetooth binary blobs in order work. Run the command below to retrieve those files.

west blobs fetch hal_espressif


It is recommended running the command above after west update.

Building & Flashing

Simple boot

The board could be loaded using the single binary image, without 2nd stage bootloader. It is the default option when building the application without additional configuration.


Simple boot does not provide any security features nor OTA updates.

MCUboot bootloader

User may choose to use MCUboot bootloader instead. In that case the bootloader must be build (and flash) at least once.

There are two options to be used when building an application:

  1. Sysbuild

  2. Manual build


User can select the MCUboot bootloader by adding the following line to the board default configuration file. ` CONFIG_BOOTLOADER_MCUBOOT=y `


The sysbuild makes possible to build and flash all necessary images needed to bootstrap the board with the ESP32 SoC.

To build the sample application using sysbuild use the command:

west build -b esp32s2_franzininho --sysbuild samples/hello_world

By default, the ESP32 sysbuild creates bootloader (MCUboot) and application images. But it can be configured to create other kind of images.

Build directory structure created by sysbuild is different from traditional Zephyr build. Output is structured by the domain subdirectories:

├── hello_world
│   └── zephyr
│       ├── zephyr.elf
│       └── zephyr.bin
├── mcuboot
│    └── zephyr
│       ├── zephyr.elf
│       └── zephyr.bin
└── domains.yaml


With --sysbuild option the bootloader will be re-build and re-flash every time the pristine build is used.

For more information about the system build please read the Sysbuild (System build) documentation.

Manual build

During the development cycle, it is intended to build & flash as quickly possible. For that reason, images can be build one at a time using traditional build.

The instructions following are relevant for both manual build and sysbuild. The only difference is the structure of the build directory.


Remember that bootloader (MCUboot) needs to be flash at least once.

Build and flash applications as usual (see Building an Application and Run an Application for more details).

# From the root of the zephyr repository
west build -b esp32s2_franzininho samples/hello_world

The usual flash target will work with the esp32s2_franzininho board configuration. Here is an example for the Hello World application.

# From the root of the zephyr repository
west build -b esp32s2_franzininho samples/hello_world
west flash

Open the serial monitor using the following command:

west espressif monitor

After the board has automatically reset and booted, you should see the following message in the monitor:

***** Booting Zephyr OS vx.x.x-xxx-gxxxxxxxxxxxx *****
Hello World! esp32s2_franzininho