Spite, Thrift, and the Virtues of an Affordable Logic Analyzer

[Larry Wall], the father of Perl, lists the three great virtues of all programmers: Laziness, Impatience, and Hubris. After seeing that Saleae jacked up the prices on their popular logic analyzers to ludicrous levels, [CNLohr] added a fourth virtue: Spite. And since his tests with a Cypress FX3 over the last few days may lead to a dirt-cheap DIY logic analyzer, we may soon be able to add another virtue: Thrift.

The story begins a year or two ago when [CNLohr] got a Cypress FX3 development board for $45. The board sat unused for want of a Windows machine, but after seeing our recent article on a minimalist logic analyzer based on an FX2, he started playing with the board to see if it could fan the flames of his Saleae hatred. The FX3 is a neat little chip that has a 100-MHz General Programmable Interface (GPIF) bus that basically lets it act like an easy to use FPGA.

Prepared to spend months on the project, he was surprised to make significant progress on his mission of spiteful thrift within a few days, reading 16 bits off the GPIF at over 200 megabytes per second and dumping it over the USB 3.0 port. [Charles]’ libraries for the FX3 lay the foundation for a lot of cool stuff, from logic analyzers to SDRs and beyond — now someone just has to build them.

The search for a cheap but capable logic analyzer is nothing new, of course. Last year, both [Jenny List] and [Bil Herd] looked at the $22 iCEstick as a potential Saleae beater.

Thanks to [themreadbeard] for the second tip of 2018.

41 thoughts on “Spite, Thrift, and the Virtues of an Affordable Logic Analyzer

  1. I was coming in to defend Saleae tooth-and-nail, having purchased several of them over the years. Customer support, analog functionality and nice software all count in their favor.

    But before doing so, I double checked the prices. They have almost doubled since my last order. Not sure why. They *are* very good bits of kit, and offer functionality and protection far beyond the dev board approaches. They have come a long way since the initial offering of what was effectively a re boxed Cypress USB dev board.

    But yes, that price is insane. Can’t argue with that at all.

    1. Just looked at their site for the first time in a while, as I need a few more for work. When I began breathing again, I started muttering ‘nope, nope, nope, nope’….. Looks like I am going somewhere else. I do wonder if this is a (misdirected) response to the knockoffs that just direct users to the Saleae software.

      1. I think some of them now have FPGA-based compression and acceleration – but for 90% of purposes, the older Salaes are just overpriced FX2 boards. Back in the day they did have the advantage of nice software, but sigrok has closed much of the gaps, and in addition has 100% open source FX2 logic analyzer firmware.

    2. Yeah, and the analog side of saleae is surprisingly useful also. Quick checks of voltage levels when you already have the probes connected, and easy to monitor current draw (with µCurrent or similar preamp) or voltage dips while executing code.

      It’s sad that they have to keep raising the prices, presumably to fund software development as the hardware is not that expensive.

    3. One of te co owners is a huge Steve Jobs fanboy, he almost bankrupted whole company with his obsession of making their products small for no particular reason and insisting on 0402 in house pick and place. Full form over function. The story is in one of old Amp Hour episodes.

    4. Umm, Literally $1000 for 16 channels? I have a 32 channel 200Mhz unit, with USB, FPGA based, that i spent less than $300 for…like ten years ago, with a software package at least as capable as Saleae’s . I have always thought Saleae to be a bit overrated, and the here we are. The proof is in the pudding i guess…

      1. What analyzer do you have? Is it USB-2.0 or otherwise unable to transport the transition data in a dense stream? 200 Mz is a meaningless number if it can’t analyze a 16-bit data bus running at 66 Mz. Also. Analog. The KEY for me why I wanted a Saleae was it did analog!

        If it is USB-3.0 and able to keep up, I want to see it.

          1. @cnlohr I have an older DSLogic Pro (straight 0.1″ header, not the system of blocks or whatever) and the software now supports both buffer and stream. The max buffer sample rate is 400MHz for 4 channels, 200MHz for 8 channels, and 100MHz for 16 channels. At least in the larger sample lengths, it does use RLE. In stream mode, the sample rates are 100MHz for 3 channels, 50MHz for 6 channels, 25MHz for 12 channels, and 20MHz for 16 channels.

  2. I’m surprised that he hadn’t tried changing the GPIF “waveform” (basically, the encoded configuration for the GPIF logic in the FX3) as it actually supports 32-bit data (at 100MHz) which allows you to use all of the USB3 bandwidth.

    1. You have to use isochronous transfers, otherwise you can get buffer underflows. It’s difficult to coax usb chipsets into going over 256MB/s with full isochronous transfers… It’s even harder to get that speed and still get the FX3 to behave itself.

  3. Did a little search for “fx3” on github. Found:
    Quote: “Experiments getting a Cypress FX3 SuperSpeed USB3 dev kit to behave as a logic analyzer.”
    https://github.com/schnommus/libsigrok-cypress-fx3-test

    A long time ago I wanted to buy a Salaea FX2 8-channel analyser.
    But even then I found $100 a bit steep for a USD5 chip in an aluminum box.
    Instead I settled for a $5 FX2 clone from Ali and used it with Sigrok and I’m quite happy with that combination.

    1. I don’t know how I missed that. It does look like they did almost exactly what I did. Gonna have to compare notes and see where they shot ahead and use some of their stuff… Gonna be a little weird license-wise.

    2. After reviewing it, it seems they went a pretty different direction than I did… Bulk transfers, directly inline in the sigrok driver, etc. Also, I can’t really seem to find where they have the stuff to build the firmware…

  4. Take a look here: https://blog.saleae.com/pricing-update/

    Seems like a rational decision – for example, the company I work for bought some at the higher price, because it’s still a good value for what you’re getting. Still way cheaper than most of our gear.
    Some people can still request older pricing (repeat customers, etc), and there’s still student discounts available.

    All that said, an affordable DIY solution would be great to see.

  5. I have some problem with people complaining about the costs of a device “as it is only … in a box”, people forget about the years of development and effort being put in a device to make it look like it is a simple device.
    Complaining about cost is mostly because we are spoiled by the cheap shit from China.

    Though I do have to admit that the prices Saleae now charges is far beyond realistic, many years ago their 8-bit product was perfectly suited for the hobby market. I was proud to be an early adopter, Saleae even send me a replacement when my first model broke and was very helpful in solving GUI requests with their software. Regarding the costs of the device today, this no longer seems to be the case. To be honest, for this amount of money the charge today, I won’t be buying another one. And I highly doubt if I ever will be purchasing one for work. I really hope Saleae is coming to their senses and return to their low-entry market with low-entry prices. I know it will be hard for them to beat the cloning market, but I’m sure that they can make it more difficult for the cloners to use the saleae software in combination with a cloned device. Unique ID /key programmed in every saleae device or registration of the software or whatever. This problem is difficult, but isn’t unique. I hope they succeed as their products itself simply delivers what it promises.

    In the meanwhile it is good to see that other people are working hard to achieve the goal of an affordable analyzer. Because in this year and age of hobbyists grabbing arduinos to control all sorts of digital devices, a good tool for debugging can be a real lifesaver.

  6. Just glad to see someone admit that Larry Wall, the nutty professor of perl, wasn’t wrong about everything. His sideways view into reality has some benefits as long as you have a Damian Conway around – the mad scientist – to make it work.
    Or this guy – I wouldn’t mind having a few things added to the canon. Or cannon.

  7. First off, hats off to Charles — much respect to him, he is amazing.

    This is a classic example of engineers trying to turn a great idea into a business.
    Saleae had a GREAT product, but failed to recognise some very very basic things,
    like what their GREAT product actually was, and that is logic-analyzer SOFTWARE.
    The hardware was basically the cypress CY7C68013A “on a stick” — absolutely nothing
    special. Its an 8051 and a USB engine that bootloads the ’51 code over USB. This is
    basically the reference design, except they put it in an expensive aluminum case. As
    far as I can see they didn’t even bother with basic DRM authentication in their software.
    So, the chinese copied it with great ease, and e sold it with the “valuable” part of the
    product (the software) included for “free”.

    Now that they are loosing money hand over fist, they raised their prices, and they
    are now deeply in (and above) the price range of their competition, who, quite frankly
    have been doing a better job, with better hardware, for years. See tech-tools Digiview,
    (truly a “transitional” logic analyzer, not a pump-and-dump data engine)

    Either way, the true challenge is not getting data into the PC (which Charles has done
    in record time with great skill!) the “real” challenge is developing a wonderful user interface,
    which Saleae has done with great skill.

    Saleae, if you wish to survive this disaster, I strongly suggest you open-source your
    hardware, and find a way to charge people a reasonable fee for the use f your software.
    some ideas may be:

    1) sell a crypto-chip that you software looks for or a fair and reasonable price that makes
    me want to support your effort. (like a MCS3142) that the user solders in place on the
    analyzer.
    2) Sell your product for LESS (not more) money and point out to the crowd that they are buying
    the ue of you excellent user interface.
    3) Realize that no hacker gives a crap about a $25 CNC aluminum case for the $5 circuit board
    you are selling
    4) Add hardware to deal with LVDS, and other voltage standards (adding value to your hardware)
    5) Offer to support other analyzer hardware (like what Charls is working on)

    Good luck yo you Saleae, you need it. This “new” pricing plan is some of the worst
    business management I have ever witnessed.

    1. Bad business if you attempt to make money off the hobbyist market, sure. But they’re still the cheapest logic analyzer around if you’re a professional and don’t have the time to dink around with DIY solutions.

      That said, I only know of Saleae because of their old cheap 8-channel digital-only offering from years back. If I were in their boots, I’d offer a $100ish “hobbyist-grade” analyzer similar to what they were selling in the past: no fancy aluminum case, no USB3, no analog support, 8 channels max, which is still more than enough to get a beginner started and get that name-brand recognition in their head.

      1. “But they’re still the cheapest logic analyzer around if you’re a professional ”
        Wrong. The Tech-tools Digi view runs circle around it – especially if you need
        high speed, multiple voltage standards, and real triggering. (I do not work for /
        with / profit from Digiview — it is just an excellent tool that I have owned many
        in the past years)

      2. Obviously you haven’t looked very far beyond the Maker blogosphere for test gear. They are far from the cheapest tool available! They just happen to be the ones gouging hobbyists who are relatively new to the game and don’t know the test gear market very well.

    2. It doesn’t help them that Sigrok has closed a VERY large portion of the software gap.

      The Sigrok team liked the fx2 LA concept but were very much against the whole piracy thing – which is why there’s now 100% open-source fx2 logic analyzer firmware.

  8. It is a mistake to price a USB dongle analyzer the same as a full-featured mixed-signal standalone scope with 16 channel analyzer from Rigol. And Rigol isn’t even the cheapest player in the game.

  9. $45.94+shipping. You can get a chinese knock off with cables and clips for a little less:

    https://www.ebay.com/itm/New-USB-Logic-100MHz-16Ch-Logic-Analyzer-for-ARM-FPGA/252569763963?epid=694885287

    Also there’s the $6 FX2 clones:

    https://www.ebay.com/itm/24MHz-8CH-USB-Logic-Analyzer-8-Channel-Logic-Analyzer-Compatible-to-Saleae/162134953459

    For over 100mhz, a vintage second hand HP or Tektronix Logic Analyzer would be a good purchase. There’s not a big demand for them as they’re big boat-anchors from the pre-hipster generation. But there are plenty on ebay.

  10. The Dangerous Prototypes Open Source Logic sniffer is a good start for those that dont need bandwidth and the power of FX2/FX3 , i have used one now for over two years and as a hobbyist I don’t feel the need for a ‘more power’ product. As the demon core part of DP OSL is open source maybe that could be ported. It’s also a very hardy product and I’ve often neglected to check the voltages i’am sniffing (although these days 90% is below 5v) , the software side is also good with sigrok and the original OLS front end. Then there’s the SDRAM based sniffer which is still being developed aka the sdramThing. (https://hackaday.com/2016/07/19/hackaday-prize-entry-the-cheapest-logic-analyzer/)

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