HAL for working with atsamd21 devices

This crate provides a type-safe API for working with atsamd21 based devices. Currently this crate only supports atsamd21g18a, but as that is fleshed out we'll look at supporting other similar variants (pull requests for this are welcomed!).

Examples?

Check out the repository for examples:

https://github.com/wez/atsamd21-rs/tree/master/examples