Budget Logic analyzer, which one do you recommend ? - Page 1
Forum section: electronics / testgear

author: bonux
author_rank: Newbie
timestamp: January 30, 2016, 10:22:38 am
content: Hi everyoneI am an electronics hobbyist (french... nobody's perfect)and I'd like to purchase an used Logic analyzer on the bay.I program cypress PSoc 5LP and I already use saleae logic USB analyzer to debug my applications.I'd like to own a desktop LA because at some point, I might consider trying parallel communicationand I'd like to learn how to handle a "real" one.So here is my question : which model/ brand would you recommend for an affordable, serial decode capableLA with limited multichannel acquisition capacity (I won't need more than 32 channels in the near future...) ? I've already browsed the internet and HP/Agilent16700+ seem to lack serial protocol decode, and Tektronix 700 series seem more appropriate but I'm not certain of this.thanks for your advice !Have a good day,Michel

author: Pinkus
author_rank: Frequent Contributor
timestamp: January 30, 2016, 10:32:37 am
content: take a look at the Intronix Logicport. Download the full software at theirwww.intronix.comsite. It is fully functional and -when no Logicport is attached- it simulates it. It takes a few minutes to get over the quirks of the software (non standard functioniality of mouse buttons etc.) but then it is OK.

author: bonux
author_rank: Newbie
timestamp: January 30, 2016, 10:36:09 am
content: Hi pinkusthis product seems really fine, looks like an upgraded saleae Logic.I should have pointed out that I am looking for a standalone device, and both saleae and intronix need a PC.Thanks for your timely answerMichel

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: January 30, 2016, 11:31:34 am
content: Well, I guess most people here will tell you to stay with the USB solution. I have a standalone LA at work (relatively new windows based HP, but also used the older ones) and used it only once or twice because it's loud and annoying.These things are are nice for multichannel capturing and setting up complex trigger conditions but serial communication is not their strength. The older ones simply couldn't do this as they were meant for address/data bus analysis of external ROM/RAM (some can even show disassembly) and the newer (window based) one could probably decode it but the protocol decoders are insanely expensive.For things like I2C, SPI and the like, IMHO nothing beats an USB based LA. Where it must be clear that your Saleae clone is on the very low side of things.If you don't really need the 32 channels, you could have a look at the Ikalogic Scanaplus (9ch but hey, it's French), else you could have a look at the Acute LAs, e.g. Acute TL2136B (36ch) - but they are a different price class.

author: Warhawk
author_rank: Frequent Contributor
timestamp: January 30, 2016, 11:38:09 am
content: Quote from: bonux on January 30, 2016, 10:22:38 amI like and use open bench logic sniffer from dangerousprototypes.com

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: January 30, 2016, 11:52:52 am
content: Quote from: Warhawk on January 30, 2016, 11:38:09 amSo did I but let's be honest: the development for it stopped years ago, there was never a GUI that supported the complex trigger setup and the memory is pretty small.Then again, it's still the cheapest 32ch solution - even though adding the 2nd 16ch needs some kind of tinkering.

author: george graves
author_rank: Super Contributor
timestamp: January 30, 2016, 12:09:40 pm
content: If you like great software that is multi-platform, and has continued updates - I really likehttps://www.saleae.comBut it's not "budget" - $200 for a 8 ch.Heck, if you're really looking for next to noting and own a laptop that has a parallel port - just a buffer chip and some free software is about as cheap as you can go.

author: bonux
author_rank: Newbie
timestamp: January 30, 2016, 12:16:30 pm
content: Ok I get it, I'll stick to my saleae logic8 - I own a genuine one, made in San Fransisco(btw outstanding customer service) .When I move to some parallel (16+ channels) interfacing I might ask again for some piece of advice.to clarify... "budget" device would be around $500, a fraction of the cost of a modern LA.ThanksMichel

author: cdev
author_rank: Super Contributor
timestamp: January 30, 2016, 03:19:16 pm
content: Sigrok.org has a big chart that lists most of the cheap logic analyzers.A great many including some very cheap ones are compatible with the open source sigrok software.

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: January 30, 2016, 04:56:18 pm
content: Yeah, but being supported by Sigrok doesn't necessarily mean it's supported in a usable way or with all features. E.g. I understand you could use a ScanaPlus with Sigrok, but then you lose all the triggering possibilities.But admittedly, Sigrok support is some kind of insurance for obscure Chinese devices and probably also the better choice compared to the included SW in some cases.BTW: after it looked grim for a while, it seemsDSLogicis back in business. End of last year they released a new version of their SW which now seems to support RLE. The technical data always looked good: 16ch, 256MBit on board RAM, proper input protection, streaming mode for low sampling frequencies, on board RAM for high frequency sampling up to 400MHz.The improved "Pro" version is sold on eBay for 99€ which is a pretty good price, also the software looks usable. It was also discussed here in the forum a few times.

author: uncle_bob
author_rank: Unknown
timestamp: January 30, 2016, 06:27:05 pm
content: HiSo .. to answer the original question:The gotcha with a "real" logic analyzer is that the ones you actually would *want* to use are not exactly cheap. I find that anything before (roughly) a TLA 700 is painful to go back to after using the USB stuff. That's a Windows 95 based device so you have a few headaches to deal with there. It's going to require logic pods and all the cables and connectors to get it running. By the time you get it all running, you probably have the same money invested as one of the good USB devices. ($600 or so).Moving forward in time from there (at least to Win XP) drives the price up past that.Bob

author: bson
author_rank: Unknown
timestamp: January 31, 2016, 12:50:07 am
content: Depends on the budget! The Salae Logic Pro 8/16 is excellent for doing deep captures/bus dumps at up to 500MHz and total bargain compared to an MSO scope of a comparable class. However, it has some huge limitations in its trigger capabilities, and unlike a capable MSO scope (at 15x the price for a 500MHz bandwidth) can't trigger on say a framing error, or log events in a table, or correlate them in a segmented capture with analog channels to actually track down the root cause. You can perhaps create custom decoders for this though, and write software to do long scans of multi-gigabyte traces to help track down problems, but then of course you're taking on additional projects rather than make progress on the main task at hand. That said, my Salae Logic Pro 16 is a great tool and I can't recommend it enough - just understand it has trigger limitations and the software is very basic.

author: cdev
author_rank: Super Contributor
timestamp: January 31, 2016, 12:50:46 am
content: Since Sigrok supports a wide range of devices, it would be cool if you could synchronize them in the time domain and visualize more channels, by adding more cheap hardwarecombine data from both analog and digital domains, etc.Okay, I am sure this is not so easy perhaps, because of internal caching and so on, and also USB timing is notoriously unpredictable. But there might be a workaround by having all the devices sample some common pulse string, which then could be used to sync the data further downstream.That could likely be very useful in labs too. Lowering the cost of data acquisition.

author: uncle_bob
author_rank: Unknown
timestamp: January 31, 2016, 01:40:00 am
content: Quote from: cdev on January 31, 2016, 12:50:46 amHiHaving done a lot of that sort of thing ... you do indeed need a unique timing bit stream running into the front end of each device. It's likely more than just a pulse every so often. Something like a time code (there are a whole raft of them) might be a better choice. Some of the things that USB and your OS do can be really scary timing wise (when nanosecond alignment is what you are after).The next layer to the onion is that you have a bunch of free running sample clocks. They likely slip a few microseconds (out to a few hundred us) relative to each other over a second. Whatever you do to line them up will have to do clock estimation and some sort of resampling to take care of the various rates.Bob

author: tggzzz
author_rank: Super Contributor
timestamp: January 31, 2016, 10:11:32 am
content: The cheaper and simpler the tools, the more you have to have to use ingenuity and imagination. And the faster they are to learn how to use.Ingenuity and imagination are a superb way to demonstrate competence during job interviews. And are helpful in a job too!You can do a surprising amount with a few LEDs and printf statements and carefully structured design and test, including some protocol decodes and timing measurements.

author: cdev
author_rank: Super Contributor
timestamp: January 31, 2016, 05:59:03 pm
content: If this forum teaches people to think like that, its worth its weight in gold!This got me started on a rant of sorts, its an important subject, though, the entry level pathway to a profession is in mortal danger. I am going to leave it out from here, though. Arrgh.Quote from: tggzzz onTodayat 05:11:32

author: bonux
author_rank: Newbie
timestamp: February 01, 2016, 12:11:22 am
content: thanks everyone for your knowledgeable replies ! Very nice.@Uncle_bob : for sure that a working TLA700 is pricey, and no guarantee on the bay purchases. If I happen to find oneat a bargain price, are the installation diskettes/CDR easy to find ? Are the SPI/I2S decode software available or do these functions require a licence ?@bson : the logic8 is very handy for simple debugging, i use mine everyday.Michel

author: uncle_bob
author_rank: Unknown
timestamp: February 01, 2016, 12:42:38 am
content: HiNothing on a 700 series device is "for sure". It's Windows 95 for goodness sake. Simply finding install disks for Win 95 is not a simple task. The one I have still runs on it's original hard drive. I (work) bought it with the licenses that I needed. It is on the top of my list titled "instruments I pretty much never use".Bob

author: bonux
author_rank: Newbie
timestamp: February 01, 2016, 07:28:36 am
content: You're right, win95 is pretty much behind us... but I sometimes use this OS in a virtual machine, to run the older PC games.By the way, just for the record which instruments are on the top of your list?Michel

author: uncle_bob
author_rank: Unknown
timestamp: February 01, 2016, 12:47:57 pm
content: HiWhat I have found is that I really do not do any parallel bus work anymore. Everything is serial bus these days. In my case that's a self driven sort of thing. I pick the bus as part of the design, tell the customer what it will be and go from there. So what do I use:I've got a TEK scope on the bench at work that will do serial decoding. It also will do 4 channels of data If I need that. Even used it's crazy expensive. For home, I have a 1054Z along with a bunch of other stuff. If I do need something past serial, I have one of the USB logic analyzers both at home and at work. The TEK 704 is also at work, but it just sits there.Bob

author: alank2
author_rank: Super Contributor
timestamp: February 01, 2016, 01:04:39 pm
content: I finally ordered a pro 16 from Saleae because my logic 16 and logic 8 are just so darn useful. I am looking forward to the USB3 speeds and bandwidth for digital and also the analog capability. More than a couple times lately I've had to haul my scope near a project and get all the probes connected and being able to see some analog with the LA will save me from that in most conditions.

author: janoc
author_rank: Super Contributor
timestamp: February 01, 2016, 03:37:39 pm
content: Quote from: 0xdeadbeef on January 30, 2016, 11:52:52 amThe 2nd 16ch only needs a buffer chip. There is actually a "wing" available for this from the DP site, I believe, but otherwise trivial to roll your own - it it is identical to the buffer you have on the board already. I have got it when I have bought mine.The worst issue with this device is the tiny memory (it uses the FPGA block RAM only), so if you are looking for capturing something more lengthy, look elsewhere. But if you need 16-32channels, it is by far the cheapest solution, indeed.

author: jancumps
author_rank: Unknown
timestamp: February 01, 2016, 03:53:11 pm
content: Quote from: bonux on January 30, 2016, 12:16:30 pmIf your budget is really tight: I'm using a Papilio FPGA board as logic probe. You can load a ported 16-channel version of dangerousprototypes Logic Sniffer bitstream on it.Works if you have 3.3V signals only. Measures needed if you want to probe higher signals.My board doubles as analyzer and as FPGA learning board.The bitfile is available from the papilio forum:http://forum.gadgetfactory.net/index.php?/topic/1925-porting-logic-analyser-from-one-to-pro/

author: janoc
author_rank: Super Contributor
timestamp: February 01, 2016, 04:48:09 pm
content: Well, if you don't have the Papillio (great dev board, btw!), then buying the Openbench Logic Sniffer is probably cheaper and you get the necessary buffer/level translator built in.

author: pickle9000
author_rank: Super Contributor
timestamp: February 01, 2016, 05:08:18 pm
content: Quote from: cdev on January 30, 2016, 03:19:16 pmSigrok and a cheap analyzer are worth it just for the protocol decoding.