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Awesome Open Source


C++ framework for writing applications based on Espressif's ESP-IDF.


Unless you're seriously intending to contribute to the project, please do not fork. Press that ⭐️-button instead - it shows your support for the project while keeping the number of (potentially) dead forks to a minimum.


Smooth provides a set of classes that makes life as a developer easier compared to working directly with ESP-IDF & FreeRTOS APIs. An application built with Smooth is entirely event driven and thread-safe*. Smooth utilizes the power of FreeRTOS, but hides all the complexities from the application programmer.

Traditionally, embedded systems require a fully static memory footprint after start-up. Smooth takes a somewhat more pragmatic view on this; it utilizes the standard library (which is not memory static) to provide cleaner code, at the cost of some extra used bytes of RAM. However, where it is appropriate, such as with the queues, things are designed so that the result is a memory static instance, i.e. a smooth::ipc::Queue will have a memory static footprint once initialized.

mock-idf provides the ability to compile even applications that uses ESP-32 hardware for Linux with the only consideration that the mocks do not actually simulate the hardware.

*) To certain limits, of course.


  • ESP-IDF v4.x
  • GCC 8

Smooth is developed on a Linux machine so how well it compiles using the Windows toolset povided by Espressif is unknown. If you are working on Windows or you don't want to install the dependencies on your local machine you can use the docker images which are provided.

Provided functionality


  • Application initialization
  • Wifi configuration / control
  • Tasks
  • Queues with support for proper C++ objects, not just plain data structures
  • Timer Events
  • Event-driven TCP Sockets, including TLS support and server sockets.
  • System events

Hardware level

  • Output
  • Input
  • Input with interrupt to event translation
  • I2C Master Device class
  • SPI Master Device class
  • Flash and SDCard initialization.

Application level

  • HTTP(s) Server
    • Simple templates
    • Websocket support
  • MQTT Client
  • Device support
    • SPI
      • Sensors
        • BME280
      • Displays
        • ILI9341
        • ST7735
        • SH1107
    • I2C
      • BME280
      • MCP23017
      • DHT12
      • AxpPMU
      • PCF8563
    • RGB LED, i.e. WS2812(B), SK6812, WS2813, (a.k.a NeoPixel).
  • Filesystem helpers

Using Smooth in your project (compiling for ESP)

In your projects's root folder, type the following to add smooth as a submodule.

git submodule add externals/smooth

Then, to retrieve Smooth and its submodules, run:

git submodule update --init --checkout --recursive

Assuming you are following IDF's recommended way of structuring projects, make your top CMakeLists.txt look something like this:

cmake_minimum_required(VERSION 3.10)



# Include Smooth as a component

    # Empty project when not building for ESP (i.e. when loading the project into an IDE with already configured tool chains for native Linux)

Next, your main/CMakeLists.txt should look something like this:

cmake_minimum_required(VERSION 3.10)


set(SOURCES main.cpp

idf_component_register(SRCS ${SOURCES}

Now build your project using the following commands, or via a properly setup IDE.

cd your_project_root
mkdir build && cd build
cmake .. -G "Ninja" -DESP_PLATFORM=1 -DCMAKE_TOOLCHAIN_FILE=$IDF_PATH/tools/cmake/toolchain-esp32.cmake && ninja

or, if you're using old-fashioned make

cd your_project_root
mkdir build && cd build
cmake .. -DESP_PLATFORM=1 -DCMAKE_TOOLCHAIN_FILE=$IDF_PATH/tools/cmake/toolchain-esp32.cmake && make

Next, flash your project to the target device. -C .. --baud 921600 -p /dev/ttyUSB1 app-flash monitor

If it's the first time, use this command instead to also flash the partition table: -C .. --baud 921600 -p /dev/ttyUSB1 flash monitor

Menuconfig / sdkconfig

Don't forget to configure your target properly by running ninja menuconfig to update your file sdkconfig before building. There is an sdkconfig file included with Smooth and used in the test projects. While you can use it for as a base by copying it to your project root, you are encouraged to adjust it to your specific needs and use case.

Sample/test applications

Please see the the different test projects under the test folder. When compiling these, open the root of the repo as a CMake project. Select the project you wish to build by setting selected_test_project in the top CMakeLists.txt. You will likely have to re-generate your build files after changing the selection.

Using Smooth in your project (compiling for Linux or MacOS)

System Libraries

Some libraries provided in the ESP distribution need to be installed as system libraries on the host. On Debian / Ubuntu:

apt-get install libsodium-dev libmbedtls-dev

With Homebrew on MacOS:

brew install libsodium mbedtls

CMake Config

To build your application on the host platform you must maintain a parallel build configuration as follows:

Top CMakeList.txt


    # Include Smooth as a component
        include_directories(SYSTEM /usr/local/include)


Your main/CMakeList.txt:

cmake_minimum_required(VERSION 3.10)

set(SOURCES} app.cpp app.h)

    idf_component_register(SRCS ${SOURCES}
    add_executable(${PROJECT_NAME} ${SOURCES})
    target_link_libraries(${PROJECT_NAME} smooth pthread)
    target_include_directories(${PROJECT_NAME} PRIVATE ${CMAKE_CURRENT_LIST_DIR})

Building on MacOS

Currently only GCC is supported. You can install GCC via homebrew and then pass flags to CMake to use that compiler:

brew install gcc
mkdir cmake-macos
cd cmake-macos

Here's an example of how your main.cpp could look like if you want to compile for both ESP and Linux. The example assumes you have named your main class App and it is derived from smooth::core::Application, which most applications based on Smooth do. Doing so is not mandatory, it saves you some setup; see Application.cpp for details on what it does for you.

extern "C"
void app_main()
    App app{};
int main(int /*argc*/, char** /*argv*/)
    App app{};
    return 0;


Running CI scripts locally

If you want to test your changes in Smooth, you need to pass the CI on Github. To test your changes on your local system you can use docker:

  • to compile the host binaries: docker-compose run --rm smooth ./CI/
  • to run the host unit test: docker-compose run --rm -w /src/build/host/test/linux_unit_tests smooth ./linux_unit_tests
  • to compile the esp32 binaries: docker-compose run --rm smooth ./CI/

To run these commands at once you can run this script: ./CI/

Run a host build with TCP ports

On default docker-compose is not opening the ports in in the run mode. To open the TCP ports for server testing you need to enter the docker image in this way:

docker-compose run --service-ports --rm smooth

Choose different release branches for the ESP32 build

For the esp32 binaries the mainline branch is used on default. If you want to use a release branch you have to set the environment variable ESP_IDF_VERSION. Here is an example with the v4.2 release branch: ESP_IDF_VERSION=release-v4.2 docker-compose run --rm smooth ./CI/

In CI, all compatible branches of IDF are checked on each push and pull request.

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