Proposal for Configure baudrate trait

[unizippro]

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This trait lets the implementer choose the type for Baudrate as this is done in different ways in different crates. Returning a result lets the implementer sort out bad, incompatible or impossible bauds, or simply return an unsupported error. An implementation can be seen at stm32l4xx-hal/feature/change-baud/ In this implementation the clock freq is saved with the Uart struct, and the used to change the baud. If the clock frequency were to change the Uart would have to be reinitialized anyway.

[rust-highfive]

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[timokroeger]

Thank you for tackling this issue. Could you please provide an example on how to use the new Trait in a generic driver?

[unizippro]

I see now that this function should be able to be called from tx and rx. But since they don't hold any reference to registers I'll leave this as a draft for now. A solution may be to return (tx, rx, config) from split, but i won't be investigating this for now.