Intronix LogicPort Compendium

[Electro Fan]

Hi EEVers,

Just in case anyone wants a compendium of Intronix LogicPort related stuff you could have found on your own by surfing the web here it is.

Disclaimer:  I don’t work for Intronix, have any affiliation with them, or even own a LogicPort, but I’m thinking about purchasing one.  Just trying to facilitate discussion about the LogicPort among anyone interested (current users, former users, potential users, or users of other products).

This is driven by my indecision on whether to purchase a Rigol DS2000 (lots of performance and features but only 2 channels) or a DS1000Z (slightly less performance and features but with 4 channels); the LogicPort might be a good companion to the DS2000, or maybe also a good companion to the DS1000Z.

My biggest (only?) bugaboo about trying to marry the Intronix (which I’m confident is a great USB LA) with a scope is that while you could trigger the LogicPort from a scope’s trigger output there will always be (according to Intronix) some (usually fixed) delay between the actual signal and the scope’s trigger output.  As a result the signals will not be perfectly correlated between the two displays and this will make navigating/reviewing/correlating the waves in either display somewhat less seamless (more difficult?).  The more I think about this the more I think the DS1000Z is probably the right choice for my interests.  YMMV – but I’m up for any thoughts and I’m hoping to help others in a similar position think through the tradeoffs.  My guess is for the basic serial protocols the 1000Z can trigger and decode the 1000Z might be the right way to fly, and a LogicPort could be added later – but even so I’m still major league on the fence between the 1000Z and the 2000 (that big Navigation knob on the 2000 seems to be calling my name …  “Electro Fan, over here”)   

PS, feel free to add links to other related info, and any comments, of course.

Intronix LogicPort (and related) posts (some old, some new, some with facts, some with opinions, etc, etc.):

http://ecee.colorado.edu/~mcclurel/LogicPortAnalyzerNotes_4-30-2011.pdf

http://www.esawdust.com/blog/serial/files/LogicPortSerialTrigger.html

https://sites.google.com/site/eecsprojects/home/digital-system-projects/adding-serial-pattern-trigger-feature-to-logicport





http://www.embedded.com/electronics-blogs/other/4422394/LogicPort-USB-Logic-Analyzer

http://www.avrfreaks.net/index.php?name=PNphpBB2&file=printview&t=86153&start=0

http://home.mit.bme.hu/~szanto/mlab_eng/ml1_m2_eng.pdf

http://www.add.ece.ufl.edu/4924/docs/LSA_Tutorial.pdf

https://www.eevblog.com/forum/reviews/intronix-logicport-34-channel-logic-analyzer-teardown/

http://forums.parallax.com/showthread.php/91323-Intronix-LogicPort-LA1034

http://systembus.com/Databook/Microprocessor/ARM/Philips/NXP/Logic%20Port_en.chm.pdf

http://www.edaboard.com/thread146631.html
"Also I found the guy who runs the company (Harrison) to be very helpful when
I had some queries about the availability of a trigger-out signal, or whether the
FPGA could be tweaked to give a trigger-out.

He said that he'd updated the PCB to have a trigger-out connector, and that if
I opened the case I could cut a little slot and solder in a 2-pin right-angled
header. There is a fixed cycle delay on the trigger-out (as the trigger logic is
heavily pipelined to sustain the 500Mhz sample rate) but I just wanted it to
trigger a DSO near the area of interest, it worked very well for me."
PS, not sure if the immediately above posted info is current or if there is a newer approach available from Intronix (maybe without the cutting/soldering) - EF

http://www.circuitpop.com/logicport1.html

http://nearfuturelaboratory.com/2008/06/21/logicport-overview/

http://forum.eetindia.co.in/BLOG_ARTICLE_18424.HTM

http://www.societyofrobots.com/robotforum/index.php?topic=12514.0
http://bikealive.nl/logic-analyzer.html

http://www.evaluationengineering.com/articles/200804/small-instruments-with-big-performance.php

http://www.jamesnsears.com/projects/

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

http://www.edaboard.com/thread177975.html
-   everyone has an opinion

http://embeddedgurus.com/stack-overflow/2010/10/digiview-logic-analyzer/

http://www.rcgroups.com/forums/showthread.php?t=1023934

http://www.pctestinstruments.com/

[alm]

If you would trigger the scope from the LogicPort, you might be able to use probe deskew (if available on the Rigol) to compensate for the triggering delay.

[Electro Fan]

If you would trigger the scope from the LogicPort, you might be able to use probe deskew (if available on the Rigol) to compensate for the triggering delay.

Interesting idea.

In searching on deskew capabilities for Rigols I didn't find anything (yet, still looking) but I saw this:
http://www.eetimes.com/document.asp?doc_id=1316013
http://cdn.rohde-schwarz.com/dl_downloads/dl_common_library/dl_manuals/gb_1/r/rt_zf/RT-ZF20_UserManual_en_02.pdf

[alm]

This is just a fixture to attach the probes to while you adjust the deskew, especially useful if you're trying to match the timings of voltage and current probes. Other scope manufacturers like Agilent and Tek have similar fixtures. It won't allow you to apply deskew on scopes/probes that lack support for it.

[nctnico]

What kills the LogicPort is the short memory even with 'compression'. I'd buy a second hand real logic analyser from Agilent / Tektronix or get an MSO.

[uoficowboy]

What kills the LogicPort is the short memory even with 'compression'. I'd buy a second hand real logic analyser from Agilent / Tektronix or get an MSO.

Kill is a strong word. I agree that the LogicPort's biggest weakness is the limited memory depth. I have found the memory depth to be sufficient for about 99.9% of what I do. But every once in a while it sucks.

I haven't played around with external triggering, so I cannot comment on that.

I will echo that the guy behind the Logicport has been super helpful in the past. I bugged him for a little while about getting a CAN interpreter and he fairly quickly added one that works great.

The software is very good, though it remains Windows only which will annoy an occasional person.

Triggering options are really good, as is the speed, number of channels, UI, interpreters, etc.

Oh - one other minor complaint - it requires use of a USB cable with USB A plugs on both ends. Not a big deal, but it's really strange.

[nctnico]

What kills the LogicPort is the short memory even with 'compression'. I'd buy a second hand real logic analyser from Agilent / Tektronix or get an MSO.

Kill is a strong word. I agree that the LogicPort's biggest weakness is the limited memory depth. I have found the memory depth to be sufficient for about 99.9% of what I do. But every once in a while it sucks.

I have used the LogicPort in the past and sufficient is the right word. Its so much easier to just capture a large chunk of data and look through it for a problem then having to setup exact triggering conditions which may or may not capture the problem.

[Electro Fan]

What kills the LogicPort is the short memory even with 'compression'. I'd buy a second hand real logic analyser from Agilent / Tektronix or get an MSO.

Kill is a strong word. I agree that the LogicPort's biggest weakness is the limited memory depth. I have found the memory depth to be sufficient for about 99.9% of what I do. But every once in a while it sucks.

I have used the LogicPort in the past and sufficient is the right word. Its so much easier to just capture a large chunk of data and look through it for a problem then having to setup exact triggering conditions which may or may not capture the problem.

This seems to be a years old debate:  Does the LogicPort have enough memory?  Overall, the word sufficient seems to describe the consenus - there seem to be many more proponents of the LogicPort than detractors; it's hard to find as much support for almost any other USB LA in this price range.

It might be nice if we could get a more detailed description of when/where (for what use cases) the memory size is truly sufficient and when/where it becomes an issue.

It is hard to understand how on one hand "what kills the LogicPort is the short memory even with compression" but then hear on the other hand that the solution is to "capture a large chunk of data and look through it for a problem [rather than] having to setup exact triggering conditions which may or may not capture the problem".  How do you capture a large chunk of data with a short memory?  I'm confused  , as is often the case   

Does this mean the problem is the memory length, or the difficulty of setting up the triggering (although I thought the triggers were generally agreed to be very good on the LogicPort), or maybe it's lack of familiarity with how the LA was intended to be used?

Net, net:  it's hard to tell after reading the many posts regarding the LogicPort's memory size just how big of an issue this is, or how easy or hard it is to work around it, or how much memory would cure the problem (to the extent it is a problem) - but if I was an Intronix company owner/product manager I'd either try to get out in front of this a bit further with more marketing (some white papers or other literature - or maybe some posts here ), or consider introducing a "LogicPort 2" that would offer however much memory it takes to put this to rest.  Seems like if Intronix could put the memory issue away nicely once and for all and maybe add something along the lines of a deskew feature that could somehow help synchronize the LA with a DSO at another notch of precision (don't know if that is even possible) they could run the table for USB LAs while Rigol and other manufacturers struggle to get their DSOs turned into MSOs for under $3k.

[alm]

It surprises me that they haven't come up with an updated version with more memory. They're pretty much the best in their price class apart from that minor issue. They've been milking the current hardware and software for years, I don't think we've seen any major new features in either in the past few years. Surely they could come up with one with SDRAM support, even if only at the lower sampling rates. Even the Chinese competitors manage to get this right.

[nctnico]

My old situation: a logic analyser (PM3655 IIRC) with 2k memory. This leads to tedious iterations of setting up a trigger condition, reproduce the problem -again-, capture data and trying to narrow the problem down further.

My new situation (Tektronix TLA700 series): I just capture several Mpoints of data and look through the data using the search tools.

Every now and then I replace CRT displays with TFT displays. One thing I need to know for such projects is the exact timing for the line & frame sync, clock polarity, etc. For that purpose I just capture one or more frames at a high timing resolution. If I need to know something about the timing later on I just look at the data I captured earlier. No need to take new measurements.

Ofcourse you can always 'make do' but with the relatively low prices of second hand real logic analysers or the extra money for an MSO instead of a DSO its hard to justify the cost of a LogicPort.

[Electro Fan]

My old situation: a logic analyser (PM3655 IIRC) with 2k memory. This leads to tedious iterations of setting up a trigger condition, reproduce the problem -again-, capture data and trying to narrow the problem down further.

My new situation (Tektronix TLA700 series): I just capture several Mpoints of data and look through the data using the search tools.

Every now and then I replace CRT displays with TFT displays. One thing I need to know for such projects is the exact timing for the line & frame sync, clock polarity, etc. For that purpose I just capture one or more frames at a high timing resolution. If I need to know something about the timing later on I just look at the data I captured earlier. No need to take new measurements.

Ofcourse you can always 'make do' but with the relatively low prices of second hand real logic analysers or the extra money for an MSO instead of a DSO its hard to justify the cost of a LogicPort.

nctnico - Thanks for the info/explanation.  Looks like the TLA series can be pretty sweet if you can find all the pieces and have the needed skills.

http://www.ebay.com/itm/TEKTRONIX-TLA-714-COLOR-LOGIC-ANALYZER-W-EXTRAS-TLA714-/111129490847?pt=LH_DefaultDomain_0&hash=item19dfd5759f&nma=true&si=6pVWEms2UPXYP2%252Fv21g9ApAAP8E%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557

In my case I might need something a bit more readily packaged but I definitely appreciate you and others sharing your experience and insights.  EF

[JDubU]

My biggest (only?) bugaboo about trying to marry the Intronix (which I’m confident is a great USB LA) with a scope is that while you could trigger the LogicPort from a scope’s trigger output there will always be (according to Intronix) some (usually fixed) delay between the actual signal and the scope’s trigger output.  As a result the signals will not be perfectly correlated between the two displays and this will make navigating/reviewing/correlating the waves in either display somewhat less seamless (more difficult?). 

FWIW,  I just measured the trigger out delay on my DS2072.  I just used channel 1 to edge trigger on a square wave and then used channel 2 to view the trigger out signal.

The delay appears to be a consistent 225ns delay with +/- 4ns jitter.
It seems to me that the important result is the +/- 4ns jitter since the overall 225ns delay can be visually compensated for, assuming that the logic analyzer has a viewable pre-trigger sample buffer.

[Mark_O]

This seems to be a years old debate:  Does the LogicPort have enough memory?

It does, for what it's designed to do.

It is hard to understand how on one hand "what kills the LogicPort is the short memory even with compression" but then hear on the other hand that the solution is to "capture a large chunk of data and look through it for a problem [rather than] having to setup exact triggering conditions which may or may not capture the problem".  How do you capture a large chunk of data with a short memory?  I'm confused  , as is often the case 

The way that you capture a large amount of data with a short memory is to store only the changes.  I.e., if the current sample is identical to the previous sample, don't store a redundant copy.  "But, but" I hear you asking.  "How can that work?"  It works by associating a counter with each of the sample memory slots.  Instead of storing another copy of an identical sample, you just bump the count.  That, along with the need to run at 500 MHz, is why the sample-size is constrained.  You can't just "add more memory".  They're already using specialized parts to achieve their current performance.  And they don't come in bigger sizes (that's my impression, in any event).

Does this mean the problem is the memory length, or the difficulty of setting up the triggering (although I thought the triggers were generally agreed to be very good on the LogicPort), or maybe it's lack of familiarity with how the LA was intended to be used?

The triggers are very good.  But, a) they take time to set up, and b) you have to know what you're looking for, in advance.  When you've got 1M samples (or 6M, or 48M, etc.), you don't have to be selective.  You can just capture a huge chunk, then browse it afterwards.  As long as your post-processing functions are adequate (searching, markers, etc.), you can find all sorts of things without pre-configuring detailed triggers.  In fact, with "error flagging" or "difference marking", you can designate a correct wave section and find all the variations without configuring any complex triggers manually.  And best of all, you can and will notice things (e.g. anomalies) you never knew were there, and didn't even know you needed to set triggers for.

Net, net:  it's hard to tell after reading the many posts regarding the LogicPort's memory size just how big of an issue this is, or how easy or hard it is to work around it, or how much memory would cure the problem...

Nico already explained it to you in a nutshell, that would be really hard to beat...

Its so much easier to just capture a large chunk of data and look through it for a problem then[sic] having to setup exact triggering conditions which may or may not capture the problem.

He nailed it.

[Electro Fan]

Mark_O and nctnico,

Thanks - I'm sure there are lots of readers here who are learning from your diligent explanations.

I hope one or both of you can get your hands on a DS1000Z with the various trigger, segmented memory, and decoding options.  Some video tutorials from you guys would probably help Rigol sell still more scopes  , and maybe help a few existing users get even more good productivity from their gear.

EF

PS, videos comparing and contrasting the use of 1000Z vs. the use of an Intronix LogicPort for RS232, I2C, and SPI applications (and maybe some other related work) would probably garner some strong viewing numbers.

[alank2]

PS, videos comparing and contrasting the use of 1000Z vs. the use of an Intronix LogicPort for RS232, I2C, and SPI applications (and maybe some other related work) would probably garner some strong viewing numbers.

This - I am in exactly this position.  I've got a DS2072 which I truly love, but sometimes it isn't enough channels.

I was thinking about getting a DS1074Z because I'd like the 4 channels.  It would certainly do that, but I'm not all that thrilled with the way the decoding works on Rigol scopes.  I feel like you get a lot for your money with the DS1074Z.

Then I started considering a LogicPort instead because it is much more capable of logic analysis.  It really does do so much although I agree that a larger sample buffer would have been handier.  I especially like that you can leave the software in a running acquisition mode and watch signals in real time like you can leave a scope in running mode.

Decisions decisions....

[neslekkim]

I got this now, and bought hooks from these suppliers:

This one in US, still have some:
http://www.ebay.com/itm/171741734361

And this seller in Korea, sold out it seems now:
http://www.ebay.com/itm/121555784010

But I wonder, I guess the Logicport cannot monitor rs232 signals right?, due to the voltage levels?

[nctnico]

The problem with grabbers is that they let go at a rate exponentional to the number of grabbers connected. 1 grabber will release in 1 hour, 2 grabbers will let go in 15 minutes, 4 grabbers will let go in less than 4 minutes....
I usually use a 2.54mm pin header with (enamel) wires soldered to the board.

[nfmax]

I have a whole bunch of Hewlett-Packard grabbers which were originally supplied with a 1615A logic analyser. I used Electrolube 'contact cleaner/lubricant' to renovate them & they work fine with the Logicport leads. However, they aren't really suitable for SM devices.

[neslekkim]

But I wonder, I guess the Logicport cannot monitor rs232 signals right?, due to the voltage levels?

Do anyone know this?, from experience ?

[Howardlong]

But I wonder, I guess the Logicport cannot monitor rs232 signals right?, due to the voltage levels?

Do anyone know this?, from experience ?

I can't remember ever needing to put it on raw +/-12 RS233, the standard logic level signals the other side of the MAX232 or whatever translator is used (if it even uses +/-12) are usually convenient enough.

[RAWebb]

But I wonder, I guess the Logicport cannot monitor rs232 signals right?, due to the voltage levels?

Do anyone know this?, from experience ?

The product spec page has more than one item that would seem to address this:

Input dynamic range: 10 volts peak-peak
Maximum input: +/-40 volts DC, 15 volts peak-peak pulse amplitude

The conservative answer would be "No." However, I've used and abused mine for more than a decade, including on RS-232 and NTDS "A" (0 to -15V) and it just keeps working. It's still the first thing I reach for when I need a logic analyzer. It's one tough old bastard.

Also note that many RS-232 interfaces do not drive to the full +/- 25V permitted by the standard. The good ol' MAX232 chips typically drove at +/- 7.5V or thereabouts.

Conservatively, though, a little voltage divider would be indicated just to be on the safe side.

[Fraser]

I have been keeping my eyes open for a Logicport on the UK secondary market for some time. I already own several Logic Analyzers from the likes of the Logicube, Hantek and various Chinese 'stables'. The Logicport has a good reputation and quite a following which is always good to see.

As I have discovered whilst owning many USB type Logic Analyzers, it is really the software that makes or breaks the product. Sure a quality hardware platform is important but, as Hantek and Chinese units have proven, poor software renders such less than great when in use. The Logic cube offerings are pretty good, but I had a hankering to try this Logicport unit.

At last I have found, and bought, a used unit that is in great condition and perfect working order. It wasn't exactly cheap at GBP75, but then good quality does tend to cost, even when bought on the secondary market.

Very happy with the unit so far. It only arrived today so not much time to play yet

Thanks for this interesting thread.

Fraser

[nfmax]

As I have discovered whilst owning many USB type Logic Analyzers, it is really the software that makes or breaks the product.

A day after the fair for you, Fraser, but the Logicport software will run in demo mode without the hardware connected.

Max

[Fraser]

Thanks. Yes I found the software on their website before buying and was pleased to see that it had a demo mode.  I had a quick 'play' and was happy with what I saw. I like the fact that it has some common protocol decoders included. My Logic Cube has masses of protocol decoders as well, so I am well sorted on that front

Fraser