Re: [gentoo-embedded] High Speed Serial Problem

[wireless]

David Relson wrote:

> I'm porting a DOS application to Linux and have encountered problems
> with the high speed serial devices from which the app receives data.



Well here is link to a home brewed Serial Chip buffering
circuit, that may better allow you to look at the signals
and protocol interactions on your serial ports. I have found
the hardware ckt to help (stabalize) bit sniffing on serial
communications. The keyword is 'eavesdropping' as used
by embedded designers. What good about this project, is it
is an easy, practical work that allows you to learn the art
of eavesdropping on a com link, rs232C being the vintage
form. RS485 will come much easier into enlightenment for you....


You can download the tar file from here:

http://sourceforge.net/projects/serialsniffer/



If you look at the file: LinuxSPA.png (after unpacking the
tar file), you'll see the circuits; I used gimp, then you
can see the chips used to buffer the signals are the old
reliable 1488 and 1489.

I'm not sure about the max speed, I believe its around
500kbps, so you might have to find newer, faster
replacements chips for the 1488 and the 1489.....


When you go to test your hardware/software between the new
embedded linux system and a tried and proven dos based
system, this sort of buffering circuit is very valuable to
keep from "loading/distorting" the signals between the 2
different devices, particularly as the speed of
communications increases.


You can look at both ends of the serial communications
with 2 different windows on each side of the comm link, to
discerning transmission issues, such as timing sync, skew
etc etc.


hth,
James