"Leland C. Scott" wrote in
:
"Slow Code" wrote in message
nk.net...
"Leland C. Scott" wrote in
:
"Jim Hampton" wrote in message
...
Has gone? Hmmmm ....
Not really
I'm just glad a few folks can get a few posts across with a bit of
sanity -
even if only once in a while 
It's been a load of fun reading the wild posts about me. It's like
sitting back with a cold one and watching a dog chase it's own tail
for hours on end because it's too dumb to know better. From reading
the posts the really dumb ones stand out from the crowd. Better they
left their mouths shut rather than opening it thus relieving all
doubt.
Anyway I've had better things to do the last few weeks, finally got my
TI 320C6713 DSP EVM boad with the development software so I've been
busy with another engineer buddy working on some DSP projects. Nothing
like going back to review all the discrete time system theory, FFT's
and z-transform stuff I learned years ago. It's a lot more interesting
than the silly name calling and baiting to start a flame war going on
in this news group lately and I don't want to waste my time with such
crap either Jim.
That gave me a headache, I got the TAPR 56000 EVM, Put it together.
Tried some 9600 packet, and 400 bps psk telemetry when A0-40 was still
working. I have it collecting dust now, as soundcard software is
easier. Don't even hook up my MFJ-1278 TNC anymore either.
I wouldn't say that the sound card software approach is "easier" at
least from a design standpoint. From a user's point of view you're right
about the ease of use, you can't beat it. The main difference between a
DSP board as opposed to sound card software is performance. And that is
a two part issue. One is raw computational performance and the second is
power consumption. The TI 6713 on my EVM gets barely warm while cranking
out 1200 to 1300 MFLOPS. Then take a look at the monster sized CPU in
your PC and it's heat sink. No contest. A last point DSP chips don't
waste transistors on stuff that isn't needed like virtual memory,
privilege levels etc. that only matters to CPUs running general
applications and need to be protected from other users on the system.
One of the things that the TI EVM development software does for you is
the complex scheduling of the various routines that have time critical
deadlines to meet. If you do the sound card routine, writing it yourself
that is, you have to not only do the application code but you have to
write your own scheduler routine and maybe with multi-level interrupts
you assign to the different threads running.
Writing code for DSP chips has gotten easier now that most vendors have
"C" compilers you can use. And at least with TI they have a DSP BIOS
that handles the low level hardware crap so you don't have to using
assembly code. Add on hardware often comes with plug-in modules
containing the required low level code so you don't have to write it
yourself. You just call the low level routines from "C" using the
provided function prototypes in the vendor's "xxx.h" files and the
linker finds the code in the vendor supplied library files.
One of the interesting things I've found out is some hard-core
audiophiles are using some of the DSP EVM boards to do some custom
filter and complex frequency-gain adjustments etc. I've seen some lively
discussions among some of them over which EVM system is best to use or
going a roll-your-own approach is better. Some of them were looking for
doing direct digital to audio applications, some audio equipment has
direct digital outputs, with noise reduction etc. because they don't
like the limitations of the commercial gear out there.
Thanks for the post. It's refreshing to have an intelligent exchange of
messages compared to the infantile crap some others are trying to get me
to waste time on.
http://focus.ti.com/docs/toolsw/fold...k6713.html#top
TMS320C6713 EVM
http://www.dspguide.com/pdfbook.htm Free for down load a text book on
DSP theory
My EVM came with five thick books. I went through part of the first one
and realized to write my own software for it, it was going to take some
time to learn things. So I mainly used software written by others. Why
re-invent the wheel. I still don't have a lot of time to play, but maybe
someday I'll plug it in again and learn a little.
SC