HAL for working with atsamd21 devices

This crate provides a type-safe API for working with atsamd21 based devices. Currently this crate supports atsamd21g18a or atsamd21e18a (selectable via the samd21g18a or samd21e18a features), and should be able to support other variants in a similar fashion; pull requests for this are welcomed!

Examples?

Check out the metro_m0 board support crate examples:

https://github.com/wez/atsamd21-rs/tree/master/metro_m0/examples