embedded software boot camp

DigiView Logic Analyzer

Wednesday, October 6th, 2010 by Nigel Jones

Today is one of those rare days on which I recommend a product. I only do this when I find a product that has genuinely made my life easier, and which by extension I think will also make your life easier. The product in question is a  DigiView logic analyzer. Now the fact that logic analyzers are useful tools should not be news to you. Indeed if you have been in this business long enough you will no doubt remember the bad old days of debugging code by decoding execution traces on a logic analyzer. That being said, I almost stopped using logic analyzers because they were big, expensive, difficult to set up and highly oriented towards bus-based systems. Given that I had my own consulting company with limited cash, limited space and a propensity to work on non-bus based systems (i.e. single chip microcontrollers), it’s hardly surprising that a logic analyzer wasn’t part of my toolbox.

This state of affairs persisted for a number of years until I obtained via a convoluted route a DigiView DV1-100. This is a USB powered, hand-sized box, with 18 channels at 100 MHz. It’s successor (The DV3100) sells for $499. The device sat on my shelf for a while until I decided to give it a spin one day. Since then I have found it to be an indispensable tool. Interestingly I find I use it the most when implementing the myriad of synchronous protocols that seem to exist on peripheral ICs today. While it is of course very useful for getting the interfaces working, I also find it extremely useful in fine tuning the interfaces. Via the use of the logic analyzer I can really examine set-up and hold times, clock frequencies, transmission latencies and so on. Doing so has allowed me to dramatically improve the performance of these interfaces in many cases. Indeed, I have had such success in this area that I now routinely hook the analyzer up, even when the interface works first time. If nothing else it gives me a nice warm fuzzy feeling that the interface is working the way it was designed – and not by luck.

Another area where I find it very useful is when I need to reverse engineer a product. I do this a lot as part of my expert witness work – and it is really quite remarkable how much you can learn from looking at a logic analyzer trace.

Anyway, the bottom line is this. $499 gets you an 18 channel 100 MHz personal logic analyzer that can handle most of the circuitry most of us see on a daily basis. If you value your time at all, then the DigiView will pay for itself the first time you use it. Go hassle your boss to get one.

19 Responses to “DigiView Logic Analyzer”

  1. Sheldon says:

    I’d used a GoLogic unit in the past, but always found it cumbersome and finicky to work with. Just a few days ago I ordered the USBee ZX logic analyzer ($379). One of my deciding factors was that it could decode so many serial protocols for me. We’ll see how well it works when it arrives in the next few days!

  2. Embedded Flyer says:

    I own a DV3100 and I’m fairly impressed with it. The combination of a generous amount of hardware memory (512K per channel) and excellent data compression means it can capture LOTS of information. There’s a little bar graph that shows the percentage of buffer memory used in real time and it’s kind of fun to have it trigger on your signals and then watch as the graph slowly inches up–sometimes over the course of several minutes or even hours if there’s not a lot going on with the signals being monitored.

    I was a bit skeptical as, unlike most analyzers, the DV3100 does not let you adjust the sampling rate–it’s always 100Mhz (10nS resolution). I was worried that would be over kill for slower signals and limit the sampling duration, but the excellent compression and generous memory eliminated my concern.

    Prior to the DV3100 I mostly used my Intronix LogicPort which is also a nice USB analyzer. I also have an expensive mixed signal deep memory Agilent scope but while it’s an amazing scope, it’s only a so-so analyzer.

    The Agilent is fast and has deep memory, but no data compression and the logic analyzer features are not as easy to use given the scope’s limited user interface (compared with a mouse and keyboard). The DV3100 is notably easier to use, has some triggering options the Agilent lacks (and vice a versa) but it’s slower, and of course, can’t do analog signals.

    The LogicPort is slick, easy to use, faster (500Mhz), has more channels (34 vs 18), and cheaper ($390 vs $500) but it only has 2K of sample depth per channel vs 512K in the DV3100. And that can be a deal breaker sometimes. Both have hardware compression and are USB powered. The DV3100 has more complex triggering options overall but the LogicPort is easier to set up. I like the Intronix LogicPort software slightly better but both have their advantages.

    There are some glaring omissions and annoyances with the DV3100. Oddly, it can decode CAN and I2C but not the simpler and very common SPI or even Async. The LogicPort can do all four protocols.

    And navigating the capture buffer is a bit awkward. There’s a “marquee zoom” that you’re often forced to use as there’s no wide conventional scroll bar, just a little compact one tucked in the corner that scrolls in rather coarse chunks. All too often the bit you want on the screen is just off the left side, so you click one increment to the right, and now half of it is off the right side of the screen. It’s such a common thing to do it’s frustrating the scrolling isn’t better.

    And, in a rather odd way, many of the buttons are dual function when you right vs left click. The zoom buttons, for example, work that way. Left click zooms in, right click zooms out. It’s not a normal convention and takes some getting used to. It would be nice if the mouse wheel would zoom. Overall, it’s not the sort of immediately friendly intuitive user interface the LogicPort has. But once you’re used to it, minus the clunky scrolling, it’s fine.

    • Nigel Jones says:

      Thanks for this detailed information. I too found the left click / right click dichotomy a bit strange at first. However once I got the hang of it, I rather liked it.

    • Embedded Flyer says:

      EDIT: I made a mistake above relative to the SPI and Async. I was getting the DV3100 confused with another USB instrument. The DV3100 can indeed decode both of those protocols but it’s missing CAN. The DV3100 has I2C, Async and generic Synchronous serial decoding.

      • Jeff Gros says:

        I’ve been interested in USB Logic Analyzers for a while now but I haven’t yet taken the plunge. Based on Nigel’s recommendation, I decided to give the DV3100 a look.

        Out of all the different ones I’ve looked at online, I currently like the DigiView units the best. The specs are adequate (100MHz sample rate, and most importantly, sample storage on device, unlike the USBee ZX mentioned above which transfers data on the fly to the PC), and the price is pretty good for what you get.

        My only real gripe is that while the hardware and price are great, the user interface can use some improvement. Although it has 6 markers for measuring time, you can only measure between consecutive markers. For example, you could measure between A to B, and B to C, but not A to C (confirmed by email to customer support). For only having 6 markers to begin with, I find that rather lazy.

        While CAN bus isn’t at the top of my list of features, I do think that if I’m going to plop down the cash to buy a unit which can interpret protocols, it should be able to handle all the major ones. Once again, user interface laziness.

        On the other side of the spectrum is the Intronix LogicPort. One of my clients sent me a trace taken from this logic analyzer, so I had a chance to play around with it with real data. I think it has an EXCELLENT user interface. However, as mentioned above, the storage space is unbelievably insufficient. The capture was an I2C transmission, and my client had problems getting the entire transaction because it wouldn’t fit in memory. I think the transaction was less than 100 bytes in total. If Intronix created another model with more memory, it would be a clear winner in my opinion.

        As I said, I have yet to take the plunge, so if anyone else has a recommended unit, please let us know!

        • Nigel Jones says:

          You raise an interesting point Jeff. Digi-View appears to be the clear technological winner, and yet they are ham-stringing themselves by failing to provide a top-notch UI. Given how easy it is today to produce an excellent UI, it is a little baffling.

          I also agree about your point with CAN. It needs to be added.

          • Jeff Gros says:

            I just wanted to add an update. We recently purchased the DV3200 and then upgraded to the DV3400 when I needed more inputs (debugging USB on a PLX chip; 16 bit bus quickly ate up all my pins).

            Now that I actually have a unit, I can give a bit more detail in the review.

            As I stated previously, the hardware specs are the best I’ve seen. While I definitely could use more than 32 channels, it gets the job done for most projects. The triggering works well, and the amount of sample storage on device cannot be beat.

            I found that the UI is still lackluster. I have three main gripes.

            First, they still don’t allow more than 6 markers. I don’t understand why they cannot allow as many as the user wants. It just seems silly. This makes it difficult to keep track and mark events in data streams such as I2C or SPI. The best way I’ve found to mitigate this is to use the search feature to help identify the data patterns I’m looking for and leave a few markers behind as I search.

            Second, the interface did take a bit of getting used to. Something that I didn’t know at first (I must have missed it in my first gloss through the manual) is that the buttons in the UI have different functions depending on whether you left-click or right click. It makes for a much simplified interface I suppose, but I’m not very fast, or very comfortable making multiple right-clicks in a row.

            Finally, they have a “bird’s eye view” which shows the marker locations in the data. The problem is that the data set that I capture is usually so long that the cursors all appear on top of each other in the “bird’s eye window”. If I zoom into one cursor, then I cannot see the other cursors in the bird’s eye window. The window seems to autosize itself based on how far zoomed in you are in the data. I would rather the “bird’s eye view” have its own zoom controls. That way, I could size it as I like and keep track of where my cursors are relative to each other as I zoom in and out of the data on the main screen.

            If they had fixed these 3 main issues, I would have bought one 2 years ago. The 6 markers issue was a real deal killer for me. However, I recently was butting heads at work when multiple people needed our old Agilent logic analyzer. I took a brief survey of the market, and the digi-view still seemed the best choice hardware wise.

            All that said, the UI does have a lot of great features (much of which I’ve not used yet).

            Lots of different built in protocols (still no CAN bus) make data analysis easy.

            The digiview has the capability of multiple captures events, in which each capture fills up one set of data within a project. The default upon installation is that each capture is saved in your working project, so that after 10 captures you have 10 data sets. I quickly disabled that feature once I figured it out, as it doesn’t agree with the way I usually do things. It could be useful for strange events that are particularly difficult to reproduce though. You can even search through the data sets for the event, which is pretty cool. The only problem is that it seems to loose data in between triggers in this mode. Probably because they didn’t leave any spare buffer space to allow them to keep accumulating data while the current data is sent up USB.

            They also have a table view that allows you to view protocol data (such as I2C) in table form. This looks interesting, but I’ve not investigated it thoroughly.

            If anyone is thinking of purchasing a digi-view, note that the cables can be purchased independently of the unit on the tech-tools website, or on digikey. It is worth picking up a couple of sets, as you don’t want to have to disassemble your connections on one piece of hardware when you suddenly need to hook it up to another setup.

          • Nigel Jones says:

            Thanks for the update Jeff. It is good to know about the latest models.

  3. Laz says:

    I use LogicPort with good success. The adjustible level threshold is particularly interesting when checking for glitches. Sometimes the 500K clock is important, especially for checking edge alignments on a 50MHz SPI or similar. The memory is too small. I may look at the DV3100 as an alternate for slower signals that need more depth.

    • Anonymous says:

      I thought I would send an email to Intronix to see if they had any plans create a new device with larger storage capacity. I sent it to support@pctestinstruments.com on 10/30/2010 with no reply.

      But then I thought, perhaps I should have sent the email to sales@pctestinstruments.com instead, so I tried that address on 11/6/2010. I haven’t heard a reply back from that address. It’s only been two days on that last email, but I doubt I will hear anything from them.

      Their contact page says they respond to all queries and that if I don’t get a response it is because it was rejected by a spam filter. However, I’m not seeing anything from them in my junk-mail folder, so I don’t know what to think. I’d appreciate it if someone else could give it a shot and see if they get a response.

      In the meanwhile I just have to assume that they earn a failing grade for customer service.

      • a support person says:

        I work for a manufacturer not related to any of the companies being discussed in this thread. As an FYI, we are forbidden from discussing with external customers ANY plans for future product enhancements, features, availability timelines, etc. According to our Finance Dept, releasing any of this information prior to its actual availability violates revenue recognition guidelines in Sarbanes-Oxley reporting (SOX). Not being a Finance person, i cannot elaborate any further. It’s possible that your inquiry may have actually been received but they chose to ignore it, as these governmental guidelines are never appreciated by customers.

        • Nigel Jones says:

          Thanks for this interesting tidbit.

          • Jeff Gros says:

            Indeed! I always like to hear more about the inner workings of tool and chip vendors.

            On a personal note, I prefer being told “I cannot divulge that info” than being ignored. If they actually respond, then I know that someone at the company exists. That way, if I have technical questions, I can get help, and I”m not left with an expensive paper weight.

            If I get no response at all, then I have to assume that technical support is zero, which means I automatically reject their product.

  4. Jeff Gros says:

    An update.

    It turns out that the Digiview has a plugin development kit (PDK). It took some learning to figure it all out, but it is a rather flexible system. I like it a lot. I ended up making a CANBus plugin using the PDK.

    However, a few weeks back, I need to decode CANBus, and I didn’t have time to make my own CANBus plugin. So I ended up buying the Saleae Logic 16 ($299 US), pretty much just to decode CAN Bus. Specifically I bought the Logic 16 over the original because the developers stated that the product should not loose samples if the computer USB is busy because they have increased buffering over the original Saleae Logic.

    The unit is small enough to fit in my palm and is USB Powered. Sampling ranges from 100 MHz to to 500 KHz, but using the faster rates limits the number of channels used: 3 channels for 100 MHz, 6 channels for 50 MHz, 9 channels for 32 MHz and all 16 channels for 16 MHz. The number of samples collected can also be changed from
    1 Million samples to 10 Billion samples. I really like that the tool tip popup tells you how long in seconds your data will be based on the sample rate and the number of samples. Note that in the preferences menu it is possible to enable longer captures up to 1 Terra samples, however they state that you can crash the program by running out of memory (there is a message next to the option that says in the future they will fix this).

    I’ve only used the Saleae to decode CAN bus, but it seems to do a good enough job. However, I would recommend to disable single click zoom in the preferences menu. While snapping the cursors, the software could interpret the action as a zoom accidentally. Pretty annoying.

    Speaking of cursors, they only give you two. I guess this is OK, but more is always better. As with the Digiview, I tend to like to mark my packets using cursors, and if I have a limited number it makes navigation difficult.

    The Saleae has measurements which can be displayed (width, period, frequency, cursor difference, etc). They update depending on the position of the mouse cursor. Works pretty well with what they give you.

    Navigating the protocol analyzers is easy once you know the trick. As a general rule, you can left click to drag the capture as needed. However, you can also press hidden buttons at the left/right of the signal to go to the next packet. Just hover your cursor near the edge and the buttons appear.

    Triggering seems simplistic. You can do the standard edge/level triggers. It appears that I can trigger on multiple conditions on multiple signals, but I have never tried it.

    They give you a wide variety of plugins which are available out of the box: CAN, I2C, I2S, 1 Wire, ASYNC, SYNC, paralell, SPI, DMX-512, Manchester, UNI/O. This is pretty much all the plugins I would ever need as far as protocol decoding goes. For small embedded development this is a good fit.

    Saleae also has a PDK to develop plugins if their offerings weren’t enough, but I’ve never used it.

    Overall I think that the Saleae Logic 16 is not a bad piece of hardware and gives a lot of benefit for the cost. However, if you have a few extra Franklins in your wallet ($299 vs $499 for Digiview base 100 MHz 16 channel model), I would lean toward the Digiview.

    In my opinion the Digiview is superior to the Saleae in pretty much every category I can think of, with the exception of no built in CAN Bus support. Now that I have created my own CAN Bus plugin for the Digiview, the Saleae Logic 16 will be sitting on the shelf.

    • Nigel Jones says:

      Very helpful Jeff. Thanks!

    • Eugene says:

      Hi Jeff!
      Do you have any plans to make your CAN-bus plugin publicly available? For example, the web-site of your company (pentaddesign?) could gain additional attention after adding quite unique resource 😉

      • Jeff gros says:

        Hi Eugene,

        Sorry for the late reply. I didn’t see the post. I happened to be reviewing my old post for other reasons and saw your question!

        We have no plans to release the plugin at this time. However, I’m not sure it is really necessary. I’ve been in close communications with Digiview tech support over the last couple of years due to my work on the CAN Bus plug in. My last communication with them indicated that they were contemplating developing a CAN Bus plugin as a core part of the tool.

        I would pester them about the CAN plugin. If enough people do it, it may become a core feature.



  5. Ali Reza says:

    I use the DV518 and it has some very nice features .


    The DV518 does not work on the same computer and at the same time with any Atmel programming device. Whether you have a STK 600 or an Xplained mini board of any sort of device that Atmel studio tries to talk to , it will disconnect the DV518 from the computer and you have to replug it to make it work again.

    The DV518 does not seem to have an issue with Microchip (MPLAB) or Lattice (Diamond) used at the same time as Digiview and the DV518

    I brought this issue to the attention of the manufacturer and they said they may fix it. That has been probably over a year now and nothing happened.
    One should be able to expect from a 700-800$ product to work with other common brand devices on the same computer at the same time.
    I wrote them recently and got no response , i think they put me on a black list and feel annoyed by me.

    It is really a pity that such a great product has such a major issue and the manufacturer is somehow not willing to fix it.

    • Ali Reza says:

      I have to update my previous comment.

      Finally i got my analyzer seen about and it turns out it was defective , i had the a lemon there. but the replacement unit works just fine and you guys can pretty much disregard what i said.

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