BOUNCE rtl@rtlinux.org: Approval required: Non-member submissionfrom [Anders Gnistrup <agn@city.dk>] (fwd)

[Der Herr Hofrat <der.herr@hofr.at>]

>From owner-rtl Wed Jun  6 13:41:02 2001
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Date: Wed, 06 Jun 2001 20:29:56 -0100
From: Anders Gnistrup <agn@city.dk>
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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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