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 Fri Jun  1 12:10:35 2001
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Date: Fri, 01 Jun 2001 19:00:13 -0100
From: Anders Gnistrup <agn@city.dk>
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Subject: Re: [rtl] rt_com
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Evgeni Dobrev wrote:

> hello all,
>
> i am writing a device driver for an eib (European Instalation Bus) device.
> It communicates with a serial port.  I wrote my own module which I load with
> rt_com and communicate with the device (19200 8n1)- it sends the computer a
> byte and the computer sends it back.  The problem is that I want to make the
> response time of the serial device smaller.

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