I think it is some internel timing in the UART. If the time between to chars
is "small" this might be the answer. If the time between to chars is large I
don not no.
Anders Gnistrup
Evgeni Dobrev wrote:
> Hello Anders,
>
> thank you for the advice. Now the char is sent back between 0.055mS and
> 0,089 mS after the serial port receives the char (@19200). The response
> time fluctuates though between those two values in "regular" (periodic) way.
> What could be the cause for this fluctuation?
>
> Anyway now I am within the 3bits limit :). thank you very much once again.
>
> evgeni
>
> > The problem is not the driver but the way the register in the serial port
> is
> > set up.
> > The UART does not generate a interrupt for every char it recived if it
> has't
> > been
> > tould to do so. It is the register for the input fifo.
> > I think this is what happens. ->
> > the computer recives a char.
> > It does NOT make a interrups at once but wait's.
> > It ganerate a interrupt when "No Charecters have Been removed From or
> input to
> > the RCVR FIFO During the last 4 Char."
> > (thats 1/(19200/10bits) ~2mSec.)
> > The driver catch the interrupt. do what ever you wont it to and send a
> byte
> > (0.2~ mSec).
> >
> > I can't remeber if it is posible to set the number of chars before
> interrups
> > with the rt_setup call. If not you have to make some minor changes in the
> > driver.
> >
> > Anders Gnistrup
> >
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