Sming Esp32 Architecture

Support building Sming for the Esp32 architecture.

Configuration Variables

IDF_PATH

Required. The full path to the ESP-IDF framework.

The standard location for this is /opt/esp-idf or C:\tools\esp-idf, which is a link to the versioned directory such as /opt/esp-idf-5.2. You can switch between installed versions by changing the link, or by changing IDF_PATH.

IDF_TOOLS_PATH

Required. The full path to the Esp32 tools directory, such as /opt/esp32.

SDK_CUSTOM_CONFIG

Custom SDK settings for a project can be defined in a separate file and setting this value to the location, relative to the project source root directory.

These will be added to the default SDK settings.

To make the settings current, you must run make sdk-config-clean. This will discard any changes made via make sdk-menuconfig.

Requirements

Sming requires a slightly modified version of the Espressif SDK. You can find the SDK here https://github.com/mikee47/esp-idf/tree/sming/release/v5.2. See idf_versions below for further details.

Using the Sming installation scripts are the recommended way to install these SDK versions. See Getting Started.

You can find further details in the ESP-IDF documentation.

Building

Make sure that the IDF_PATH is set. Also make sure that the other ESP-IDF environmental variables are set.

In Linux/MacOS this can be done using the following command:

source $SMING_HOME/Tools/export.sh

For Windows:

$SMING_HOME\Tools\export

Build the framework and application as usual, specifying SMING_ARCH=Esp32. For example:

cd $SMING_HOME/../samples/Basic_Serial
make SMING_ARCH=Esp32

This builds the application. Once built the application needs to be flashed on a real Esp32 microcontroller to run. Flashing can be done using the following command:

make flash

SDK

Sming comes with pre-compiled libraries and configuration files. If needed you can re-configure ESP-IDF using the command below:

make sdk-menuconfig

A re-compilation is required after the change of the configuration thus:

make Sming-build all

If you want to revert to using the default SDK settings:

make sdk-config-clean

You can also configure per-project custom settings via SDK_CUSTOM_CONFIG.

SoC variants

Sming leverages the ESP IDF HAL to support multiple processor variants.

A family of SoCs is supported, currently:

- esp32
- esp32s2
- esp32c3
- esp32s3
- esp32c2

You can change variants like this:

make SMING_SOC=esp32c3

Each variant uses a different build directory, e.g. out/Esp32/esp32c3/....

See Esp32 Core Component for further details.

IDF versions

Sming currently supports IDF versions 5.2. This is installed by default. Older versions 4.3, 4.4 and 5.0 are no longer supported.

A different version can be installed if necessary:

INSTALL_IDF_VER=5.3 $SMING_HOME/../Tools/install.sh esp32

The installation script creates a soft-link in /opt/esp-idf pointing to the last version installed. Use the IDF_PATH environment variable or change the soft-link to select which one to use.

After switching versions, run a full clean before re-compiling. This must include SDK configuration:

make sdk-config-clean clean components-clean

See ESP-IDF Versions for the IDF release schedule.

Scheduling

The ESP IDF runs on FreeRTOS which is a pre-emptive multitasking environment. However, Sming is a single-threaded framework and applications should not generally have to consider thread safety.

These are the standard tasks created for a networked Sming application:

  • wifi Deals with wifi hardware communication

  • tiT LWIP tcpip task handles traffic from wifi task. Sming code runs in this task.

  • esp_timer High-priority task which services hardware timers

  • sys_evt Services IDF events, used primarily by wifi

  • Tmr Svc FreeRTOS kernel timers

  • IDLE Idle task which runs when there’s nothing else to do

For a non-networked application (e.g. Basic_Blink) it’s much simpler:

  • esp_timer As above

  • Sming Dedicated task to service the Sming task queue (software timers and callbacks)

  • IDLE

Watchdog timer

The 8 second watchdog is reset by the idle task. This can happen if any other code runs for too long without idling. With Sming this can occur during length flash erase operations which accommodate this by including a call to system_soft_wdt_feed(). This is named from the ESP8266 SDK, but for the esp32 this just yields the current task to allow other tasks to run, which should include the IDLE task.

Components