Re: 8ms Timer for serial port access

From: Jens Schumacher (jens.schumache_at_gmx.net)
Date: 10/29/03 

Date: Tue, 28 Oct 2003 19:24:41 -0500

Hello,

> Since you are newbie, and I'm confused, would you mind if we started over?
>
> Here's what I got from above:
>
> 1) Device sends data via the serial port.
> 2) You need to collect the data.
> 3) You do not want to lose any data.
Thatıs right

> But there's a bunch missing:
>
> 1) What bit rate is the data transmitted?
The bit rate is 38400 bps

> 2) Does the data need to be timestamped?
Not really necessarily

> 3) Is the data bursty or does it come in a steady stream?
The data comes in a steady stream with 120 Hz

> 4) What makes you think that the data will overrun the serial port and kernel
> driver?
The Code at the moment calls the read function with a timer. If this timer
is not triggered every 8ms, the next data comes to the buffer and the old
data is still there...if this happens very often the buffer overflows and I
loose data.

> I'm still trying to figure out what you require from the OS. Care to explain
> the goals of the application?

Here my application goals in detail.

1) I use an Eye-tracking System which operates on the serial port with
38400bps.
2) The Eyetracker sends a package of 24bytes at 120Hz to the serial port.
3) I have to read, proceed and display this data. And this as fast as
possible since I need to detect very fast eye movements.

Do you need more datail?
I could explain my current implementation, but not sure if it's helpful. But
if you need more details about this I can describe it.

Thank you all so much.

Jens Schumacher