Fix Serial Write

[Javier-varez]

In order to guarantee the width of the start bit in a serial transfer we need ot make sure that we are waiting for the correct amount of time. Since the timer is already started we have no guarantee of the current count value and therefore should add an initial wait.

[sajattack]

I would rather take the solution in #10 but it needs to be updated to support embedded-time. Would you be able to take that on?

[Javier-varez]

I fully agree, that would be a much better solution. I'll give it a go!

[Javier-varez]

I'm not quite sure I understand the strategy to use the embedded time crate. As far as I have seen no timer hardware abstraction layers currently use the types and traits defined there, so the serial port will not work with them?

[sajattack]

I was under the impression there was better adoption.