Advice on Logic Analyzer

[Nico Coesel]

Most of these PC based instruments are very poor to start with, after
a few years they become unsupported and if you break them in the bin
they go. You would do much better looking on ebay for an Agilent or
Tek instrument for less money.

And get an unsupported piece of equipment to start with for which
getting spare parts is a matter of pure luck? I own an old & bulky Tek
LA myself, but with today's prices for USB logic analyzers I might
choose differently if I have to replace it.

 

[[email protected]]

Most of these PC based instruments are very poor to start with, after

And get an unsupported piece of equipment to start with for which
getting spare parts is a matter of pure luck? I own an old & bulky Tek
LA myself, but with today's prices for USB logic analyzers I might
choose differently if I have to replace it.

There not really unsupported, only by the manafacturer. As for parts
there is so much and so cheap you dont need much luck. They dont go
wrong often either as they were well made in the first place. And of
course they are repairable unlike your USB jobbie.

 

[logicgeek]

I am surprised, though, that Intronix hasn't come out with a follow-on
product with more sample memory. The LogicPort has been out for quite
a while (as these things go).

The reason that Logicport will not soon be coming out with a follow-
on product with more sample memory is stated in an article published
recently on Evaluation Engineering: Quote
The LA1034's logic and memory are entirely contained
within a single FPGA," commented Harrison Young III, company CEO.
"This keeps the speed up
and the cost down compared with products having
external memory interfaces. The LA1034's efficient lossless
compression algorithm allows its buffer
depth to be greatly extended with no loss in signal
integrity."
The small sample buffer available in the Logicport is that which is
available within the mentioned single FPGA, if they should bring out
anything with a slightly larger internal memory, they would have to
redesign the whole instrument. Also data compression works in certain
cases, but certainly is no magic. Otherwise every company would have
offered it, since it saves a lot of development and manufacturing
costs.

 

[logicgeek]

That depends on what you want to do with your data. I don't know about
the Janatek LA, but my own LA (a tektronix DAS9200) allows to read the
acquisition memory into the PC for automated analysis or drawing
pretty pictures on the screen based on the data.

Isn't that what any PC-based logic analyzer do in principle? Capture
the data and then relay it to its software on your pc for 'pretty
pictures' What I like about that compared to standalone LA's is the
inherent mobility it creates. You can move about with your analyzer
and keep the captured data on your flash. Most of these programs can
export the captured waveforms to a CSV, text or bitmap file that you
can e-mail or compare. If you have some time, go download their
demostration software or another manufacturers.

I'm pretty convinced to go for a pc based rather than standalone,
maybe jump with me?

 

[Rich Webb]

The small sample buffer available in the Logicport is that which is
available within the mentioned single FPGA,

Yup. And FPGAs keep getting wider, deeper, and faster, so I'd expect a
follow-on.

if they should bring out
anything with a slightly larger internal memory, they would have to
redesign the whole instrument.

Well, yeah, but that's the beauty of HDLs innit?. It's not like they'd
have to respin from, say, a discrete transistor layout to logic gates.

Also data compression works in certain
cases, but certainly is no magic. Otherwise every company would have
offered it, since it saves a lot of development and manufacturing
costs.

Once again, there is no universal, single best solution. For my part,
I've used PC-based analyzers with each approach and find that the
transitional sampling technique in the LogicPort is the better fit.

 

[Rich Webb]

On Wed, 16 Apr 2008 02:14:35 -0700 (PDT), logicgeek

[snip...snip...]

One notes that the entire posting history, via Google Groups, for
[email protected] consists of six messages subtly promoting
the Janatek product.

One notes that Janatek's mailing address is Stellenbosch,
Western-Cape, South-Africa.

One notes that, in contrast to the "yahoo.co.UK" e-mail address, the
actual posting IP is 198.54.202.254, which is a .za (South Africa)
domain with a Western Cape contact address.

Gentlemen, I think we have a sock puppet.

 

[[email protected]]

Isn't that what any PC-based logic analyzer do in principle? Capture
the data and then relay it to its software on your pc for 'pretty
pictures' What I like about that compared to standalone LA's is the
inherent mobility it creates. You can move about with your analyzer
and keep the captured data on your flash.

Data storage is standard, usually on disk, most have printer outputs
as well.

Most of these programs can

export the captured waveforms to a CSV, text or bitmap file that you
can e-mail or compare.

Are you likely to want to email your data?

If you have some time, go download their

demostration software or another manufacturers.

I'm pretty convinced to go for a pc based rather than standalone,
maybe jump with me?

Maybe you report back how you get on with it.

 

[Nico Coesel]

Isn't that what any PC-based logic analyzer do in principle? Capture
the data and then relay it to its software on your pc for 'pretty

No, it is very nice to be able to have an LA with an API or protocol
with which you can read the data into your own application.

 

[[email protected]]

Yup.  Design-by-committee never works.

I disagree, design-by-committee works more often then not. A guy in
his garage will product a vastly superior product if he doesn't give
up, run out of money, run into health problems etc etc. A large
company is mostly immune to those issues, it may produce crap, but at
least it's making and selling something!

 

[Keith M]

I would have replied to the original message, but it didn't show up on
my server. Life without giganews sucks.

Anyways.

You may be interested in something I threw together last year because I
was shopping for one too.

http://www.techtravels.org/tech/logicanalyzer.html

It's a comparison of logic analyzers under $1000 for hobbyists. It's
just springboard for research with links, basic info.

I personally own a LogicPort and it's actually pretty nice. The price
point was right. I liked the fact that it does 32-channels, out of the
box, without expansion, extra cabling, etc. 500mhz is nice although I
normally run it around 100mhz. The software is very very intuitive, and
I was up and running in minutes. The different triggers are nice for
capturing just the right signal --- there really hasn't been anything I
can't get a good look at. Software is stable.... and is freely
redistributable. It's nice for having other people who don't own the
hardware download and be able to look at your timing diagrams....

It does data compression (check the link above for description), which
is indeed very helpful for slow bursty signals. Like capturing rs-232
traffic where you might have seocnds between transmissions. It helps
with the capture depth.

Lesse..... Also, it exports the data, in .csv or whatever, which is nice
to process outside the program. It also includes decoders for the
various serial protocols. So like you can see "HEX 55" fly across
instead of just the waveforms. And you can adjust how much pre-trigger
data vs post-trigger data you capture. Are you just interested in the
events before the trigger? Or only after? Adjustable by percentage
1%/99% 50%/50% etc.

THE ONLY GOTCHA IS THE MEMORY DEPTH. It only captures 1023 transitions
across all 32-channels. It can capture these over any length of time.

While 1K sounds pitiful, in my limited hobby experience, by utilizing
the data compression & triggers, I've always been able to get the data I
wanted to look at. So, while it feels like a limitation I'd run into, I
just haven't hit it yet. Oh yeah, you can do recurring-sampling where
it will go out and do multiple-samples repeatedly, so you can extend how
much you sample....

And if you order the logicport, make sure to get those XKM grabbers.
They are tiny tweezer type things to grab onto chip legs, wires, etc.
They are really nice. I've got to order some more of those.

A lot of the other PC-based LA's don't include the serial decoders for
free, only do 8-channels (or less), are slower, and are often priced
above the LogicPort.

I'm pretty happy with the purchase, and I've had a year or two decide
that..... It would be closer to perfect if only that damn memory depth
was larger. The only other complaint is that the software feels like it
was upgraded from like a windows 3.1 interface. It's intuitive, clean,
and doesn't do anything goofy --- I just wish it was updated to be
prettier and maybe a little friendlier.

Feel free to email me any questions etc.

Keith

 

[JosephKK]

I do use a hex background debugger (the PEMicro pod, for the 68332)
when testing embedded code. It lets me load code into RAM (which will
later be eprom), run it, step it, breakpoint, patch, snoop registers
and ram. It also lets me directly thrash hardware interfaces. A
combination of untested digital+analog hardware, untested FPGAs, and
4-12 kilobytes of untested uP code, running on a brand-new pc board,
exceeds *my* ability to just think it through.

The bdm pod plugs into a little 10-pin header that we include on all
of our embedded products.

John

Do you use JTAG as well?

 

[JosephKK]

Isn't that what any PC-based logic analyzer do in principle? Capture
the data and then relay it to its software on your pc for 'pretty
pictures' What I like about that compared to standalone LA's is the
inherent mobility it creates. You can move about with your analyzer
and keep the captured data on your flash. Most of these programs can
export the captured waveforms to a CSV, text or bitmap file that you
can e-mail or compare. If you have some time, go download their
demostration software or another manufacturers.

I'm pretty convinced to go for a pc based rather than standalone,
maybe jump with me?

Naw. I want split. Capture in stand alone, USB or Firewire to PC, or
dump to memory card. Do all the heavy lift analysis on PC.

 

[JosephKK]

On Apr 15, 9:52 am, John Larkin

That's small company talk for sure!

A large company has vastly different day to day problems that what you
normally experience.

Simply not true. Been both ways, and guess what the generally support
for analyzing your logic before you build it is much better in large
companies. That generally is the gotcha.