Advice on Logic Analyzer

It's faster and cheaper to analyze your logic before you build it.

John

Well to be fair, nobody's usually dumb enough to want to sample an entire screen full of RGBI data, usually you just use a RGBI monitor for that! Looking at one line is usually enough. Except when you interlace the display, and the physically "next" line on the screen is an entire vsync time away. Of course you could program the triggers to ignore the rest of the field but now I don't remember if you could do that with the Logicport.

You know, it is spring cleaning time here in the northern hemisphere. Maybe I'll put my logicport up for sale, since I haven't used it in a year and that's an important criteria in the cleaning.

But what if you're analyzing someone else's design from twenty years ago and there's no documentation? Sometimes a new design has to work with old stuff. I wonder if there's a logic analyzer with enough input range to handle the logic levels inside a 6R1A?

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.

On Apr 15, 9:52=A0am, John Larkin

That's small company talk for sure!

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

Yup. The more people you put on a project, the less they understand.

John

Statements like these make me wonder if I should give Modelsim a try... Still, the thought of having to create a testbench doesn't appeal to me. Especially for a design that has a massive amount of configuration registers. Anyway, it all boils down to verifying your design one way or another.

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.

Yup. Design-by-committee never works.

The Girl Scouts are heading that way... combining neighborhoods so we're looking at managing 1000's of girls rather than 100's... with all functions "by committee".

My wife just outfoxed them and designated herself as Registrar and me as the Committee ;-)

...Jim Thompson

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.

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.

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?

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

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.

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.

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.

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

Most of these programs can

Are you likely to want to email your data?

If you have some time, go download their

Maybe you report back how you get on with it.

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.

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!

I bought a DigiView LA made by

Data can be exported and triggering is adequate. Its portable and I travel all over the country with it to client facilities. It won't match a benchtop model in performance, but it's been great for that portability and light - moderate use. Like most of these type products - the tiny spring clips are pretty delicate, but they can grab SMD parts.

Steve

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.

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

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