"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
--
Regards,
Leland C. Scott
KC8LDO