Tier one common examples

[TDHolmes]

Summary

Unify common examples for tier one BSPs to reduce code duplication.

Checklist

• CHANGELOG.md for the BSP or HAL updated
• All new or modified code is well documented, especially public items
• No new warnings or clippy suggestions have been introduced (see CI or check locally)
• Add compilation of these common examples to CI

[TDHolmes]

I wanted to make these all Option<T>'s, but for some reason it didn't work properly when I tried. Need to figure this out especially if we'll be vending out things like Timer's and RTC's

[TDHolmes]

Might want to have an enum argument for external_32k/internal_32k/etc.

[sajattack]

No offence, but this looks overly complicated which kind of defeats the purpose of the examples as a demonstration of how to get started with a board.

[TDHolmes]

Fair criticism, I can see that perspective. I didn't think it was too bad but it might be enough to obscure things too much for people wanting to copy-paste get started on their project. Any other opinions?

[bradleyharden]

It might work better if you have separate thumbv6m and thumbv7em examples. That seems to be driving a lot of the complexity. If you could create common examples, where the only difference is the definition of bsp, that would be ideal.

[bradleyharden]

Also, I wouldn't try to abstract away the initialization code. Better to leave that in each example, even if it's redundant. It lets each example stand on its own, and it shows new users how to properly initialize.

Edit: Let me revise that. If you want to abstract some of the clocking, then I would do it in each individual BSP, and use a common name (e.g. configure_clocks). That way it becomes like any other common convenience function in the BSPs.

[TDHolmes]

Thanks for the feedback. I think I'll close this for now and maybe revisit once clock::v2 lands. separate v6/v7 examples makes sense, that should eliminate the extra abstraction code I put in for this.