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Example of integration ESP-IDF and Rust NMEA crate

The example shows how to integrate ESP-IDF with Rust no_std crate like NMEA.

Prerequisites

• Installed ESP-IDF
• Installed Rust and Cargo
• Installed Xtensa LLVM toolchain for Rust
• Basic knowledge of ESP-IDF, CMake, and Rust

Structure

Here's how your project directory might look after the following the guide:

esp_idf_project/
|-- CMakeLists.txt
|-- main/
|   |-- CMakeLists.txt
|   |-- esp_idf_project.c
|-- sdkconfig
|-- components/
|   |-- nma /
|       |-- CMakeLists.txt
|       |-- include/
|           |-- nmea_idf.h
|       |-- nmea_idf.c
|       |-- nmea_idf_rs /
|           |-- Cargo.toml
|           |-- rust-toolchain.toml
|           |-- src/
|               |-- lib.rs

Architecture

Key elements:

• esp_idf_project contains main C code like any other ESP-IDF application.
• The ESP-IDF componet with name nmea is stored in subdirectory with components.
  • The nmea_idf_rs component contains C adapter layer which helps interfacing with Rust library.
• The Rust code is stored in components/nmea/nmea_idf_rs subdirectory.

The component can be uploaded later on to Component Manager.

Select target

Set target for main ESP-IDF application:

#idf.py set-target <target>
# idf.py set-target esp32
idf.py set-target esp32-c3
# idf.py set-target esp32-s3

Optional step when developers needs to build Rust component also manually: Define which toolchain should be used for the Rust component in file esp_rust_component/rust_crate/rust-toolchain.toml

[toolchain]
# Use "esp" for ESP32, ESP32-S2, and ESP32-S3
#channel = "esp"
# Use "nightly" for ESP32-C*, ESP32-H* targets
channel = "nightly"

Build the Project

From the base folder of the project (esp_idf_project), run the build process as you usually would for an ESP-IDF project:

idf.py build flash monitor

Build the Project in Debug

idf.py -DCMAKE_BUILD_TYPE=Debug build flash monitor

Expected output

I (316) main_task: Started on CPU0
I (316) main_task: Calling app_main()
Remaining stack space before calling Rust function in app_main: 2392
Message from Rust: Hello ESP-RS. https://github.com/esp-rs
Size of NMEA: 12272
Remaining stack space after calling Rust function in app_main: 2392
Remaining stack space before calling Rust function in nmea_gga_task: 36068
NMEA altitude: 61.700001
Remaining stack space after calling Rust function in nmea_gga_task: 25924
GGA Data:
- Latitude: 53°21.6802' N
- Longitude: -7°29.6628' W
- GPS Quality: 1 (GPS fix)
- Number of Satellites: 8
- Horizontal Dilution of Precision: 1.0
- Altitude: 61.7 Meters
- Height of Geoid above WGS84 Ellipsoid: 55.2 Meters
I (376) main_task: Returned from app_main()

Simulation

Simulation with Wokwi in VS Code

Wokwi for Visual Studio Code provides a simulation solution for embedded and IoT system engineers. The extension integrates with your existing development environment, allowing you to simulate your projects directly from your code editor.

• Install VS Code
• Install Wokwi plugin
• Activate Wokwi plugin - command palette, search for Wokwi: Start Simulator, select and ativate the plugin using web browser