This is a toy project to build a Rust runtime for the Arduino Uno R4 Wifi "from scratch", using only the core library. It currently exposes the GPIO pins and the Systick timer feature.

I don't have plans to expand this to a comprehensive library, and it is not intended for production use. Nevertheless, if anything here seems useful, feel free to take it under the MIT license. No warranties though!

Use rustup target add thumbv7em-none-eabi to install the compiler for the AMD Cortex M4 CPU. The .cargo/config file in this repository is set up to compile for this architecture by default, so you can just use cargo build.

Since this isn't a serious library, I'm not putting it on crates.io. If you clone this repository, you can use the crate by adding the following to your Cargo.toml:

[dependencies]
arduino_uno_wifi_rt = { /path/to/arduino_uno_r4_wifi_rt }

Copy the .cargo/config from this crate to yours. This is to ensure that the linker script from this crate is used.

In your application, write

#[no_std]
#[no_main]

extern crate arduino_uno_wifi_rt;

use arduino_uno_wifi_rt::entry;

entry!(main);

fn main() -> ! {
    // Your code here.
    ...
}

Check the doc comments and examples for how to access the GPIO pins.

To get your code onto your Arduino, you first need to make a raw binary from the ELF file and then upload it using arduino-cli:

cargo objcopy -- -O binary test.bin
arduino-cli upload --input-file test.bin -p /dev/ttyACM0

The following resources were very helpful with this project. If you're interested in embedded Rust for this platform or in general, I recommend checking them out.

General embedded Rust on Arm:

• Embedonomicon
• The Embedded Rust Book

Documentation for the Armv7-M architecture:

• Armv7-M Architecture Reference Manual

Documentation for the Renesas RA4M1 microcontroller:

• Renesas RA4M1 Group User's Manual: Hardware