"Leland C. Scott" wrote in
:
"Slow Code" wrote in message
ink.net...
"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
Hey, it's never to late. You stop learning when you're dead in my view.
It sure beats exchanging insults on this news group.
Yup, reusing code written by others is a good idea, why reinvent the
wheel unless you're doing it for self pedagogical reasons. In fact
that's one aim for good software engineering practice; code reuse. Was
that EVM board a stand alone system or was it part of some kit it was to
be used in? I assume you're referring to the Motorola 56000 DSP chip you
mentioned in another post.
Funny talking about DSP in this group. I normally come here to stir a
little when someone says their CB broke. LOL. I know that's mean.
Mine has the motorola DSP56002EVM. TAPR made a kit to use it in. You can
connect a couple radio's to it. It has status lights on the front you can
program to indicate various states like what you would see on a regular
multi-mode TNC. On the back is a programming port and a communications
port. My soldering iron was probably only hot for about an hour and a half
putting it together.
It's really quite neat setup, after you load the modem software you want
you can use it without having to wire every up again, or switch cables.
It's nice to have two computers hooked to it. One to use as a terminal
for what ever you're doing. PSK, Packet, etc, and the other computer to
load the modem software and program it. If you only have one computer you
have to switch back and forth. One thing I didn't do but wanted to was
burn an Eprom with the different modems on it to switch between modes
faster. What I had to do each time I used it was load what ever software I
wanted to use at the time. There was another way you could load two
different modems in it at the same time but I never did that.
If you can program yours in a higher language and compile it down to the
EVM, that's a lot better than using an assembler like I got with mine,
though some members of TAPR wrote some apps to make things easier.
Like I said, I'm not doing much with it right now. Time is the problem.
It's easiest to use the soundcard.
If you develope a new mode, you might have to port it to the PC so
everyone else can use it. There are a number of people in Amsat that
are working with DSP for the satellites. Look around for Phil Karn, he's
a good one to bounce ideas off of, and knows who else is experimenting.
Also browse TAPR, I don't know what they're doing DSP wise these days. I
was never a member. I only really got into the EVM & DSP when you
couldn't buy an AEA DSP.
SC