Choosing a Logic Analyzer: DSLogic vs Saleae vs ASIX Sigma 2

[shaunakde]

I have been working on a project with an ESP32 and need help debugging my SPI connections. I figured a Logic Analyzer would be handy for this. After looking at several reviews and recommendations, I've narrowed it down to these 3:

1. Saleae Logic 8
This company seems to be the most recommended in forum threads, and have sigrok support. It's also closer to me physically and shipping might be easier in these times. But the device seems overpriced compared to the competitors. For my $199 (hobbyist price) i'd get 100Mhz sampling and none of the models have internal buffers.

2. ASIX Sigma 2
This is an interesting device. Its supported by sigrok, costs about $280 in the USA from its distributer (ucpros). It samples at 200Mhz, has a 256 MB internal buffer with hardware compression. On the downside, it's a little more expensive, and doesnt seem to have much info available online.

3. DS Logic Plus
For my $150 I'd get a 400Mhz sample rate, and a 250mb buffer (cant find information on their compression technology, if any). On the flipside, I cant find a US distributer and might have to ship it from overseas (which isnt fun in a pandemic)

EDIT: potentially this is $70 on Aliexpress

On paper it would seem like DS Logic would be the best candidate, followed by the bit over my budget (~$200) ASIX Sigma. But I might be missing something or completely wrong about something.

I dont own an oscilloscope, so I figured investing in a half decent LA would be worth it.

[shaunakde]

Thank you for the suggestion and your experience with these products!

If you accept new options, I'd add Analog Discovery (100Msps digital and bunch of analog features) or Digital Discovery (pure digital, 800Msps).

I was not that excited about the AD or the DD because 1. Its completely out of stock and back-ordered with a possible price increase right now. And 2. It's not compatible with Sigrok at all. It's not a deal breaker, but I feel if a device is compatible with an open source tool, there is a good chance it wont become obsolete in a year. But ofcourse, I'm not against buying it (or trying to haha)

I do agree right now I probably need something under a 100Mhz, but if like to future proof myself for things like the Teensy 4.1 etc (as much as possible ofc)

[ebclr]

You need to consider the big guy from DSlogic also

https://www.dreamsourcelab.com/shop/logic-analyzer/dslogic-u3pro32/

[2N3055]

Farnell has Digital Discovery on stock and it is 161 €, which is cheaper than it was...

[robca]

I'm sure you have already considered and discarded this option, but I can't resist offering my 2 cents

I would personally start with a <$10 8 channels, 24MHz eBay logic analyzer. And use Sigrok with it (or, if your conscience doesn't bother you, the Saleae app). For <$10, you can easily troubleshoot any SPI problem on an ESP32 and more.

Then save some money to actually buy a used or low-end oscilloscope instead. Half the problems in a digital protocol like SPI or I2C are actually "analog" problems: the signal gets degraded to the point it's not recognized anymore. Or there is transient noise messing up the signals. And nohobby-level logic analyzer will help you there. You live in the USA, where finding used entry level scopes is not a problem, usually (Europeans are less lucky, smaller countries even more so). I found an incredible deal on Craigslist, a basically new DS2072A for $275, with both probes included (promptly updated to 300MHz). But even without being that lucky (I had to wait a long time), good used scopes can be found easily. Even a 100MHz dual trace analog scope like my previous Hitachi V1065 would work perfectly for the most common troubleshooting scenarios on a ESP32 or similar

Personally, I would rather have a $200 scope and $10 logic analyzer than a $200 logic analyzer only. I could troubleshoot and solve a lot more issues with the scope+cheap LA than a really good logic analyzer only

[tggzzz]

Half the problems in a digital protocol like SPI or I2C are actually "analog" problems: the signal gets degraded to the point it's not recognized anymore. Or there is transient noise messing up the signals. And nohobby-level logic analyzer will help you there.
...
Personally, I would rather have a $200 scope and $10 logic analyzer than a $200 logic analyzer only. I could troubleshoot and solve a lot more issues with the scope+cheap LA than a really good logic analyzer only

Yes.

People need to understand that, with rare exceptions, the voltages/currents are analogue waveforms that are interpreted by the receiver as digital signals. Correct interpretation relies on the waveforms having good "signal integrity", and that is evaluated with an oscilloscope.

If you have poor signal integrity then the receiver in a logic analyser may interpret the waveform differently to the reciever in the UUT.

[shaunakde]

Dear @blueskull,
That is extremely generous of you. I've recently stopped being a student, so I do want to pay for this hardware (will be one of the first things I buy for myself!) and I'll hope you are able to send your extra to someone who's a full time student.

I'm also sure that the digital discovery will be a better tool in the long run, since it has the option to add a high speed front end (if I'm not mistaken, signals beyond 200Mhz really benefit from such a buffer)

@2n3055 thanks for the tip on the distributer. I'm definately going to look into it!

@robca
To be honest, I have considered an oscilloscope for a long time (and even put money aside for it). Currently I'm in a small room, and I have very limited table space. That's why I haven't pulled the trigger yet. And till recently, I had access to a scope anytime I needed one at a local makerspace. However, I'm definately going to consider buying a super cheap LA to try, and getting a 2ch scope with some decoding ability.

Thanks for your inputs! I'm pretty sure I'm going to go the route of a cheap scope + digital discovery (after getting my feet wet with a clone from ebay)

[robca]

Thanks for your inputs! I'm pretty sure I'm going to go the route of a cheap scope + digital discovery (after getting my feet wet with a clone from ebay)

Yes, I would highly recommend getting one of the cheap 8ch clones from eBay, if nothing else than to learn more about what you need in a logic probe before spending your actual budget. Also, being so cheap and small, you might end up using it even when you have a better one.

I would not advocate to spend $50 or so for a "just to learn tool", but he cheapest logic analyzer on eBay is $8.55 shipped to the USA and $9.99 on Amazon Prime. So, for less than $10, it's definitely a bargain and well worth it. And I'm pretty sure that you'll be able to work on your SPI bus without problems

I did actually buy one of those "just to learn more and decide which real one to buy", and in the end I have not yet found a case where I would need a better logic analyzer. Admittedly I've been doing some pretty low level projects, and a couple of times I wished I had a better triggering mechanism. But with a bit of creativity (i.e. using one channel only as a trigger when other conditions are met), so far it's done everything I need. And I keep telling me that every month I can wait to buy a better one, prices get lower and more new models become available

[leftek]

2. ASIX Sigma 2
This is an interesting device. Its supported by sigrok, costs about $280 in the USA from its distributer (ucpros). It samples at 200Mhz, has a 256 MB internal buffer with hardware compression. On the downside, it's a little more expensive, and doesnt seem to have much info available online.

This is designed and produced in Czech.
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