This crate provides a type-safe Rust API for working with the Adafruit Grand Central M4 Express board.
rustup target add thumbv7em-none-eabihf
Check out the repository for examples:
https://github.com/atsamd-rs/atsamd/tree/master/boards/grandcentralm4/examples
cd boards/grand_central_m4
$ cargo hf2 --release --example blinky_basic
Finished release [optimized + debuginfo] target(s) in 2m 02s
Searching for a connected device with known vid/pid pair.
Trying Ok(Some("Adafruit Industries")) Ok(Some("Grand Central M4 Express"))
Flashing "/path/to/atsamd/boards/grand_central_m4/target/thumbv7em-none-eabihf/release/examples/blinky_basic"
Finished in 0.085s
$