Smooth

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

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Overview

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.

Requirements

• 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.

Provided functionality

Core

• 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
• Flash and SDCard initialization.

Application level

• HTTP(s) Server
  • Simple templates
  • Websocket support
• MQTT Client
• Sensor BME280
• 16 channel I/O expander MCP23017
• RGB LED, i.e. WS2812(B), SK6812, WS2813, (a.k.a NeoPixel).

Using Smooth in your project (compiling for ESP)

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

git submodule add https://github.com/PerMalmberg/Smooth.git externals/smooth

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)

set(CMAKE_CXX_STANDARD 17)

if(${ESP_PLATFORM})
include($ENV{IDF_PATH}/tools/cmake/project.cmake)

# Include Smooth as a component
set(EXTRA_COMPONENT_DIRS
         externals/smooth/smooth_component)

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

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

cmake_minimum_required(VERSION 3.10)

set(CMAKE_CXX_STANDARD 17)

set(SOURCES main.cpp
        main.cpp
        main.h
        )

idf_component_register(SRCS ${SOURCES}
        INCLUDE_DIRS
            ${CMAKE_CURRENT_LIST_DIR}
            $ENV{IDF_PATH}/components
        REQUIRES
            smooth_component
        )

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 && ninja

Next, flash your project to the target device.

idf.py -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:

idf.py -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)

To build you application for Linux you must maintain a parallel build configuration as follows:

Top CMakeList.txt

if(${ESP_PLATFORM})
    include($ENV{IDF_PATH}/tools/cmake/project.cmake)

    # Include Smooth as a component
    set(EXTRA_COMPONENT_DIRS
             externals/smooth/smooth_component)
    project(your_project_name)
else()
    add_subdirectory(main)
    add_subdirectory(externals/smooth/lib)
    add_subdirectory(externals/smooth/mock-idf)
endif()

Your main/CMakeList.txt:

cmake_minimum_required(VERSION 3.10)

set(SOURCES} app.cpp app.h)

if(${ESP_PLATFORM})
    idf_component_register(SRCS ${SOURCES}
                            INCLUDE_DIRS
                                ${CMAKE_CURRENT_LIST_DIR}
                                $ENV{IDF_PATH}/components
                            REQUIRES
                                smooth_component)
else()
    project(your_project_name.elf)
    add_executable(${PROJECT_NAME} ${SOURCES})
    target_link_libraries(${PROJECT_NAME} smooth pthread)
    target_include_directories(${PROJECT_NAME} PRIVATE ${CMAKE_CURRENT_LIST_DIR})
endif()