Logic analyzer for embedded development - Page 1
Forum section: electronics / testgear

author: Aang
author_rank: Contributor
timestamp: July 21, 2020, 09:42:43 am
content: Good day.For a long time I deal with microcontroller programming (especially STM32) and now I'd like to buy a quality logic analyzer, that would serve very well. My budget is to $200-250. I was looking at Digital Discovery from Digilent and Logic 8 from Saleae (both I could have for student price - around $220).I think that this new device from Digilent has very good parameters compared to Saleae. I also thought about an oscilloscope (it would come in handy sometimes at home, but it's on every corner at my school), but it wouldn't be very valid for me as a logic analyzer. I've been thinking about Analog Discovery 2, but it has everything possible and in fact nothing really. Would you please recommend me the most suitable equipment for embedded development? I also read here on the forum about recommendations about cheap chinese alternatives (I need reliable equipment, not plagiarism) or DSlogic, etc., but it seems to me quite unreliable and I would not know what to expect from it. Do you think such a device up to $100 will serve as well as Digilent or Saleae? I would be worried about this in this case, for the money wasted ...Thanks for your recommendation.

author: EEEnthusiast
author_rank: Frequent Contributor
timestamp: July 21, 2020, 09:45:31 am
content: I havent used the Digilent one, but the one from Salae logic is very good. The hardware build quality is excellent and their software is among the best I have seen so far.

author: ace1903
author_rank: Regular Contributor
timestamp: July 21, 2020, 09:56:58 am
content: I use everyday Saleae at work. Software is great and SDK is quite capable. You can check I2C SPI Serial in minutes.At home I have Analog Discovery 1 and Digital Discovery. Software is bit clumsy to set up and un-intuitive.Analog Discovery is much better investment as oscilloscope and logic analyzer.Digital discovery on paper, hardware is much powerful but with software as it is is underutilized.Saleae is my choice for anything lower than 10MHz. Digital Discovery maybe only if task requires parallel interface at frequencies >10MHz

author: 2N3055
author_rank: Super Contributor
timestamp: July 21, 2020, 10:28:52 am
content: One thing rarely mentioned about Digital Discovery is that it can be used as clock source and digital pattern generator.You can also create protocol packets, and write your own decodes and scripts and algorithmic pattern generator.Also it has ROM Logic for implementing user defined Boolean functions and State Machines...So it is a very interesting instrument for digital experimenting.I used it to test devices by simultaneously creating stochastic stimulus, monitoring output and serial packets going in and out from devices, and was able to find and verify lockup state in interaction and find a fix for it..Serial protocol decode is the least interesting part of it... It does have some triggering options too...

author: pascal_sweden
author_rank: Super Contributor
timestamp: July 21, 2020, 10:31:19 am
content: Check out this post!https://www.eevblog.com/forum/testgear/logic-analyzer-that-is-using-the-cypress-ez-usb-fx3-chip/

author: firewalker
author_rank: Super Contributor
timestamp: July 21, 2020, 10:31:24 am
content: I was thinking of getting the DSLogic one.https://www.dreamsourcelab.com/product/dslogic-series/Alexander.

author: tggzzz
author_rank: Super Contributor
timestamp: July 21, 2020, 11:28:54 am
content: Firstly, always ensure theanaloguewaveforms have sufficient "signal integrity" that they can be correctly interpreted as digital signals.The key features of a logic analyser are:minimum time interval you need to resolve; directly related to the sampling ratecomplex triggering and filtering, so you can find the information you need and avoid having to wade through mountains of irrelevant datacapturing a state machine's states, rather than just time-domain capture. That's one aspect of filteringwidth: how many signals need to be examinedprotocol decodingYou can do a lot with a scope, printf() statements, skill and imagination, and a thoughtful approach to "bringing up" a system (i.e. don't throw it all together and expect it to work).

author: robca
author_rank: Frequent Contributor
timestamp: July 22, 2020, 09:03:24 pm
content: Before spending serious money for a logic analyzer, personally I would first buy a cheap Logic 8 clone from eBay for less than $10 and use it with Sigrok (legally) or a copy of the Saleae software (illegally). That would give you a sense of what you need in terms of hardware and software features, speed, memory, number of channels, etcFor basic digital work with microprocessors (stress on basic), a basic 8 channel 24MHz Saleae clone will cover pretty much anything you need. Also by spending just less than $10, you can learn and spend your next $$$ better. Just look for "logic analyzer 24MHz" on eBay or Amazon, and pick one with the clips (crappy clips, but at least they will get you started... then you can upgrade)For example, if I had only a $300 budget and no oscilloscope yet, I would seriously consider buying a 2 or 4 channel basic scope and a $10 logic analyzer, not just an expensive logic analyzer without knowing what features I really need. With a scope and a logic analyzer, you can look both at the signal integrity with the scope and the protocols with the logic analyzer. As tggzzz said, many digital problems are due to noise and/or signal integrity. Things you can't really see that well with a logic analyzerAnd while it's true you can do a lot with a scope and printf() (or even better, a decent SWD/SWO debugging probe) I would not live without a logic analyzer. Especially when $10 gets you something I would have killed for in the 90s, when logic analyzers cost a fortune and were just a dream for a hobbyist

author: tggzzz
author_rank: Super Contributor
timestamp: July 22, 2020, 09:41:15 pm
content: Quote from: robca on July 22, 2020, 09:03:24 pmBasically, yes.But it is good practice to fully utilise the available tools before buying more - and it is fun to have succeeded

author: Doctorandus_P
author_rank: Super Contributor
timestamp: July 24, 2020, 08:08:11 pm
content: About the cheap USD 7 LA's from China Express...They are nothing more then a Cypress CA7C68013A in a box with some protection ciruiitry (series resistors and dual diode's).This uC has no flash, just ram and a baked in bootloader. Firmware is downloaded to it through DFU when you put the cable into your PC.I've been using these things for a few years now and I love them.Here I've posted a few screenshots and wrote some lines of how I use it to debug firmware with Pulseview.https://www.eevblog.com/forum/microcontrollers/how-to-debug-microcontrollers-in-the-real-world/msg3150912/#msg3150912Sigrok / Pulseview is completely open source software, inclusive the firmware for this LA. It's "FX2LAFW" (FX2 Logic Analyser FirmWare) and it's written with SDCC. This uC has an 8051 coreYou can also get a "generic CA7C68013A development board". These have different ID numbers in the EEprom, and Pulseview then uses it with up to 16 channels (with reduced sample rate).Years ago I thought about buing a genuie Saleaeaea, but in the mean time their prices have bout doubled. They also do not sell this simple device anymore I believe.I've also captured some low speed USB data ( 1.5Mb/s) with it just for fun, and from experimenting with it I learned more about low level USB this way than with a few days of reading boring manuals (though they are useful too of course).I do not know if this device is the right one for you, but your conscience does not have to be in the way for this choice.I've also seen this thing pop up at Sparkfun and other regular western stores, but then it usually costs around EUR25.https://www.antratek.nl/logic-analyzer-25mhz-8-channelhttps://www.sparkfun.com/products/15033Also:Because these things are so cheap, I have multiple of them, so if I damage one from some real abuse, I just take the next one.I also leave them attached to breadboards when I switch projects, which saves some hassle with the wiring.

author: cdev
author_rank: Super Contributor
timestamp: July 25, 2020, 02:52:43 pm
content: I don't have an expensive LA, I have three cheap ones. And they get a lot of use. I would go with the cheap FX2 based LAs and build test headers into your devices that you use.

author: Aang
author_rank: Contributor
timestamp: August 02, 2020, 02:38:39 pm
content: Thanks for help.So I will buy a couple of these cheap analyzers. I hope it will enough for most things...https://www.aliexpress.com/item/4000255462769.html?spm=a2g0o.productlist.0.0.1bb35c2fMsjLyg&algo_pvid=a7bac651-834d-46c9-877e-fa5bcc9947f6&algo_expid=a7bac651-834d-46c9-877e-fa5bcc9947f6-0&btsid=0ab6f81e15963791638772434e2546&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_I also found this more expensive clones, but surely the above cheap analyzer will perhapse suffice for the vast majority of things. When you say that you are satisfied with such cheap analyzers.https://www.aliexpress.com/item/32613420798.html?spm=2114.12057483.0.0.76ee4e1df5w0BOorhttps://www.aliexpress.com/item/32780046572.html?spm=a2g0o.productlist.0.0.47fd69b3cj8TWl&algo_pvid=33032503-6d2c-4d9f-876a-efb3a8fc0e74&algo_expid=33032503-6d2c-4d9f-876a-efb3a8fc0e74-1&btsid=0ab6fa8115963854081605988e1fdf&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_Is it an excellent tool or a waste of money? Does it really have that value?

author: Tarloth
author_rank: Regular Contributor
timestamp: August 02, 2020, 08:01:03 pm
content: Hi!I use for my work the Open Bench Logic Sniffer and work like a charm, better than salea or others than I try. It's completely open source, very powerful and inexpensive. With some minor modifications you can use Agilent Logic analyzers cables (I buy a bunch of new parts but old stock in ebay for less than a multimer point). A friend uses Bus Pirate and told me that it's perfect. Also completely opensource.http://dangerousprototypes.com/docs/Main_Page

author: cdev
author_rank: Super Contributor
timestamp: August 03, 2020, 05:42:44 pm
content: I just go by the supported hardware on sigrok.org. (for a logic analyzer you use the pulseview software) The cheapest one I have, I paid literally $6 for, it is just an Cypress FX2 chip in a small plastic box.I wouldn't buy multiple ones unless you know you are going to need the capability. In my case there have been times when I needed to use several at once. When I build something I include headers to plug into the logic analyzer. That way i dont have to use the fragile mini grabber clips. 8 channels is a good number of channels for me because I am a beginner.I worry that I might damage the input from ESD but in fact that has never happened.I would also get an oscilloscope if you can afford one. Often when you are having a problem its because of signal integrity. An osciloscope can show you when thats happening.Quote from: Aang on August 02, 2020, 02:38:39 pmGiven its limitations (the number of channels and the sample rate) Its an excellent tool, but you dont have to spend a lot of money because its a commodity product.You'll notice that several "dev boards" are basically the most common one used.Consult the Sigrok hardware support page. Don't use proprietary vendors software. Pulseview is quite good. This is a basic solution, but its affordable and a good introduction to the logic analyzer category of tools.

author: robca
author_rank: Frequent Contributor
timestamp: August 04, 2020, 09:28:58 pm
content: Quote from: Tarloth on August 02, 2020, 08:01:03 pmLooks interesting, but it doesn't seem to be available for sale anymore, at least in the USA...

author: Aang
author_rank: Contributor
timestamp: August 05, 2020, 11:14:40 am
content: Quote from: robca on August 04, 2020, 09:28:58 pmNo anymore:"Hello,We ask our manager again and sorry to inform you that this product is EOL and will not produce any more.Thanks for the support to seeed."By Seeed Customer Support Team

author: Tarloth
author_rank: Regular Contributor
timestamp: August 05, 2020, 02:01:31 pm
content: You can use it in some other FPGA development board or in the SUMP2 implementation. OBLS it's a concept that evolve in other products with better performance. Sump2 implemented in a RPI with independent screen is an example of that.

author: cdev
author_rank: Super Contributor
timestamp: August 05, 2020, 02:43:56 pm
content: The Bus Pirate isn't a logic analyzer. Its a versatile multi tool that can do many useful things, involving two way communication between hardware and user, though. I think it can act as a rudimentary LA, sorta kinda. But not really.It can even act as a scope (with a very limited bandwidth) NOT A SCOPE YOU WOULD WANT TO USE DAILY..but it works.In a similar way, a Arduino or Raspberry Pi can be used as test equipment, given the right software.

author: Clear as mud
author_rank: Regular Contributor
timestamp: August 07, 2020, 02:55:49 pm
content: I was looking at that Dangerous Prototypes one a little bit, that you said was not being sold anymore. I was wondering how hard it would be to just build it, since the design is public and everything. It seems like it would still be useful.I found an interesting comment on this page:https://www.seeedstudio.com/Logic-Sniffer-16-bit-Input-Buffer-Wing-p-721.htmlThe comment says that the software has not been updated since 2008 and does not work with modern 64-bit systems. So, not only would you have to build the hardware yourself, apparently you would also have to work on the software.

author: firewalker
author_rank: Super Contributor
timestamp: August 07, 2020, 03:42:56 pm
content: For the software side I think sigrok is compatible. It;s a really old design. Don't know if it worth the hassle.https://sigrok.org/wiki/Openbench_Logic_SnifferAlexander.

author: robca
author_rank: Frequent Contributor
timestamp: August 07, 2020, 09:07:04 pm
content: there's a parallel thread ongoing herehttps://www.eevblog.com/forum/testgear/usb-logic-analyzer-recommendation/.Since that one has more info, I'd suggest posting there from now on

author: annr
author_rank: Newbie
timestamp: July 12, 2021, 06:19:46 am
content: Take a look at this pull-request (https://github.com/sigrokproject/libsigrok/pull/148). This adds support for using FX3 devices as 100MHz 16 channel logic analyzers using sigrok .