[En-Nut-Discussion] 3.0 sync uart support - (Development Environ - general questions)

[Harald Kipp]

Dave,

We had been very busy to fix several bugs and try to add whatever we
can. But not every contribution made it, so doesn't the USART.

Main reason for not doing much on the UART part was, that I discovered
a big mistake in it, which exists since the very beginning of Nut/OS.

The UART driver uses TX complete for transmit interrupts, which is
miserably wrong and degrades perfomance. It should trigger on TX data
register empty.

I detected this while debugging the PPP code, which required some
rewriting as well and we didn't add the PPP_demo in 3.0 either.
One problem with PPP is, that it is added to every network enabled
application, even if it doesn't make use of PPP. Another problem
was, that it uses forbidden functions in the timer callback.

Harald