Rust on ESP-IDF "Hello, World" template

A template for a "Hello, world!" Rust binary crate for the ESP-IDF framework. Based on cargo-generate.

This is the crate you get when running cargo new, but augmented with extra configuration so that it does build for the ESP32[XX] with ESP-IDF and (by default) with STD support.

Or if you rather

• ... want to mix Rust and C/C++ in a traditional ESP-IDF idf.py CMake project - follow these instructions
• ... want to mix Rust and C/C++ with PlatformIO - follow these instructions
• ... want to develop on Windows / WSL2 - follow these instructions

For more check out the links in the additional information section

Generate the project

Please make sure you have installed all prerequisites first!

cargo generate esp-rs/esp-idf-template cargo

The command will display a few prompts:

• Project Name: Name of the crate.
• Which MCU to target?: SoC model, e.g. esp32, esp32s2, esp32c3 etc.
• Configure advanced template options?: If false, skips the rest of the prompts and uses their default value. If true, you will be prompted with:
  • Enable STD support?: When true (default), adds support for the Rust Standard Library. Otherwise, a no_std Rust Core Library crate would be created.
  • ESP-IDF Version: ESP-IDF branch/tag to use. Possible choices:
    • v4.4: Stable
    • v5.1: Stable
    • master: Unstable
  • Configure project to support Wokwi simulation with Wokwi VS Code extension?: Adds support for Wokwi simulation using VS Code Wokwi extension.
  • Configure project to use Dev Containers (VS Code and GitHub Codespaces)?: Adds support for:
    • VS Code Dev Containers
    • GitHub Codespaces Dev Containers also allow flashing from the container using web flash and have the VS Code Wokwi extension already installed.

Build

cd <your-project-name>
cargo build

• Replace <your-project-name> with the name of the generated project

Flash

In the root of the generated project:

espflash flash target/<mcu-target>/debug/<your-project-name>

MCU	Target
ESP32	xtensa-esp32-espidf
ESP32-S2	xtensa-esp32s2-espidf
ESP32-S3	xtensa-esp32s3-espidf
ESP32-C2	riscv32imc-esp-espidf
ESP32-C3	riscv32imc-esp-espidf
ESP32-C6	riscv32imac-esp-espidf
ESP32-H2	riscv32imac-esp-espidf
ESP32-P4	riscv32imafc-esp-espidf

• espflash will print a list of the recognized USB ports for you to select the desired port, if it detectes multiple boards.
• Replace <your-project-name> with the name of the generated project
• You can include the --monitor argument to the espflash command to open a serial monitor after flashing the device.
• For more details on espflash usage see the README

Monitor

espflash monitor /dev/ttyUSB0

• Replace dev/ttyUSB0 above with the USB port where you've connected the board. If you do not specify any USB port, cargo-espflash/espflash will print a list of the recognized USB ports for you to select the desired port.

The monitor should output more or less the following:

Opening /dev/tty.usbserial-0001 with speed 115200
Resetting device... done
ets Jun  8 2016 00:22:57

rst:0x1 (POWERON_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:2
load:0x3fff0048,len:12
ho 0 tail 12 room 4
load:0x3fff0054,len:4800
load:0x40078000,len:17448
load:0x4007c428,len:4840
entry 0x4007c6a0
I (178) cpu_start: Pro cpu up.
I (178) cpu_start: Starting app cpu, entry point is 0x4008115c
I (0) cpu_start: App cpu up.
I (193) cpu_start: Pro cpu start user code
I (193) cpu_start: cpu freq: 160000000
I (193) cpu_start: Application information:
I (197) cpu_start: Project name:     esp-idf
I (202) cpu_start: App version:      f08dcd7
I (207) cpu_start: Compile time:     Oct 23 2021 14:48:03
I (213) cpu_start: ELF file SHA256:  0000000000000000...
I (219) cpu_start: ESP-IDF:          4.3.0
I (224) heap_init: Initializing. RAM available for dynamic allocation:
I (231) heap_init: At 3FFAE6E0 len 00001920 (6 KiB): DRAM
I (237) heap_init: At 3FFB3498 len 0002CB68 (178 KiB): DRAM
I (243) heap_init: At 3FFE0440 len 00003AE0 (14 KiB): D/IRAM
I (250) heap_init: At 3FFE4350 len 0001BCB0 (111 KiB): D/IRAM
I (256) heap_init: At 4008C538 len 00013AC8 (78 KiB): IRAM
I (263) spi_flash: detected chip: generic
I (267) spi_flash: flash io: dio
I (272) cpu_start: Starting scheduler on PRO CPU.
I (0) cpu_start: Starting scheduler on APP CPU.
Hello, world!

License of the generated code

While the esp-idf-template repository code itself is dual-licensed by Apache OR MIT, the code generated by the esp-idf-template generator can be considered in the Public Domain - or equivalently - as if licensed under the MIT No Attribution License.

We are however explicitly not outputting any license file in the generated content, which allows the developers to add their own content on top of the generated one and the combined work would be assumed to be a proprietary work, until/if a license file is explicitly added by the developer.

Additional information

For more information, check out:

• The Rust on ESP Book
• The ESP STD Embedded Training
• The esp-idf-hal project
• The embedded-hal project
• The esp-idf-svc project
• The embedded-svc project
• The esp-idf-sys project
• The Rust for Xtensa toolchain
• The Rust-with-STD demo project

Prerequisites

Linux/Mac users: Install the OS dependencies mentioned in the esp-idf install guide.

In other words, the equivalent of

sudo apt-get install git wget flex bison gperf python3 python3-pip python3-venv cmake ninja-build ccache libffi-dev libssl-dev dfu-util libusb-1.0-0

...command for your OS, if you are not on Ubuntu/Debian.

Please:

• Do NOT do anything else from this page! Only the sudo apt install / sudo yum stuff for your OS
• In particular, do NOT clone, install and activate the ESP-IDF which is mentioned further down this page, as it is not necessary at all (though supported, but not for a beginner setup)

Install Rust (with rustup)

If you don't have rustup installed yet, follow the instructions on the rustup.rs site

Install Cargo Sub-Commands

cargo install cargo-generate
cargo install ldproxy
cargo install espup
cargo install espflash
cargo install cargo-espflash # Optional

Note

If you are running Linux then libudev must also be installed for espflash and cargo-espflash; this is available via most popular package managers. If you are running Windows you can ignore this step.

# Debian/Ubuntu/etc.
apt-get install libudev-dev
# Fedora
dnf install systemd-devel

Also, the espflash and cargo-espflash commands shown below, assume that version 2.0 or greater.

Install Rust & Clang toolchains for Espressif SoCs (with espup)

espup install
# Unix
. $HOME/export-esp.sh

Warning

Make sure you source the generated export file, as shown above, in every terminal before building any application as it contains the required environment variables.

See the Installation chapter of The Rust on ESP Book for more details.

Alternative (for RISC-V Espressif SOCs only): install & use upstream nightly Rust and upstream stable Clang

While you can target the RISC-V Espressif SOCs (esp32-cXX and esp32-hXX) with the espup installer just fine, SOCs with this architecture are also supported by the nightly Rust compiler and by recent, stock Clang compilers (as in Clang 11+):

• Install a recent Clang. See Clang Getting Started page as it contains useful guidelines on installation. Recent Linux distros come with suitable Clang already.
• Install the nightly Rust toolchain with the rust-src component included:

  rustup toolchain install nightly --component rust-src

• Run any Cargo command with the nightly toolchain override, i.e. cargo +nightly ....

Install Python3

You need a Python 3.7 or later installed on your machine.

• Linux, Mac OS X: if not preinstalled already, just install it with your package manager, i.e. for Debian systems: sudo apt install python3
• Windows: install it e.g. from the official Python site.

You'll also need the Python PIP and Python VENV modules. On Debian systems, you can install with:

• sudo apt install python3-pip python3-venv

Optionally Install GDB

You'll only need the GDB utility for on-chip debugging or for decoding backraces in panics for RISCV Espressif SOCS.

To install it:

• Manually download the GDB package matching your OS and Espressif SOC from here
• Unpack (with tar xvfz) into a directory of your choice
• Add the unpacked GDB debugger to your PATH, so that e.g. invoking riscv32-esp-elf-gdb (or xtensa-esp-elf-gdb for xtensa-based SOCs) without any path prefixes is possible, as esp-idf-monitor wants that

Install esp-idf-monitor

While espflash has a built-in monitor, its monitor is currently unable to properly decode ESP-IDF stacktraces generated by the RISCV Espressif MCUs (ESP32-CXX/ESP32-HX/ESP32-PX).

Therefore, use esp-idf-monitor instead.

• Install Python itself first
• Install GDB for your SOC

... and finally - to install esp-idf-monitor itself - do:

pip install esp-idf-monitor

To run esp-idf-monitor with panic backtrace decoding for e.g. ESP32-C3, do:

python -m esp_idf_monitor [-p your-com-port-eg-`dev/ttyUSB0`] --toolchain-prefix riscv32-esp-elf- --target esp32c3 --decode-panic backtrace <your-elf-file-that-you-just-flashed>

For other RISCV SOCs like e.g. ESP32-C6 you only need to change the --target to esp32c6, but the toolchain prefix (and thus GDB itself) would remain the same.

Using WSL2 on Windows

Using WSL2 does not exhibit path length issues; furthermore, using WSL2 reduces the waiting time between command line cargo invocations and Rust Analyzer operating on the same projects.

Setup

1. Follow the WSL2 setup guide and the WSL2 development environment setup guide.
2. Install a Linux distro as per the guide or the Ubuntu App; set up and update the packages.
3. Follow the Prerequisites section for toolchain setup.
4. Configure USB access in WSL2:
   • Install usbipd-win on Windows.
   • (Optional) In your WSL2 terminal, run:

     sudo apt install linux-tools-generic hwdata
     sudo update-alternatives --install /usr/local/bin/usbip usbip /usr/lib/linux-tools/*-generic/usbip 20

Flashing an ESP32 Target from WSL2

1. Launch WSL2 from PowerShell and run your Linux distro or launch the Ubuntu app as installed from the Microsoft Store.
2. Create a new project folder in your $HOME directory.
3. Generate a new project using Cargo Generate.
4. Build the project by running cargo build or cargo b.
5. Open a PowerShell terminal as an administrator and run the usbipd commands to share the USB device with the Linux distro.
6. Open the Linux terminal and check attached USB devices using lsusb.
7. Check the attached target with espflash board-info.
8. Flash the device:

   espflash flash target/xtensa-esp32-espidf/debug/<your-project-name>

   OR

   espflash board-info
   cargo run

9. Monitor the device:

   espflash monitor

Notes

• Once a USB device is bound, it won't lose status until a disconnect command is run from Windows PowerShell:

  usbipd detach --busid <busid>

  This remains effective even after a system restart.
• The device will get detached from WSL2 after a few minutes of being idle, system resets, or exiting WSL2. You'll need to run:

  usbipd attach --wsl --busid <busid>

  in such cases.
• It is recommended to create the project in the WSL2-hosted environment only. Accessing projects from C:\Users\<UserName>\Project or /mnt/c/Users/<UserName>/Project can lead to performance issues.
• Accessing projects from C:\Users\<UserName>\Project or /mnt/c/Users/<UserName>/Project may also cause ESP-IDF builds to fail with OS Error 2.