PC spec requirements for USB scopes and logic analyzers - Page 1
Forum section: electronics / testgear

author: ElectroSone
author_rank: Newbie
timestamp: October 26, 2022, 06:21:10 pm
content: Hi everyone,I'm a software engineer who about a year ago started on the adventure of learning electronics, with relatively modest hobbyist ambitions. I originally focused on trying to get a decent beginner understanding of analog fundamentals but lately have been drawn more toward digital logic circuits (occupational hazard perhaps).The above is the work bench I've slowly put together over the past year. As you can see my toolset at the moment is quite bare, with just a lab PSU, a DMM and a companion laptop. I'm now crossing that bridge where I don't want to go further without bringing in an oscilloscope for learning/discovery, and perhaps also a dedicated logic analyzer (replacing MCU-based hacks and homebrew code I've used so far for capture and decoding when needed by projects, since at least lines of code I can swing easily).New equipment will need table space and I want to get rid of the laptop on the table by hanging a screen on the peg board and hiding a mini PC under the table, reducing the on-table footprint to a small Bluetooth keyboard+touchpad thing I already have. Brings me to my concrete ask for the round:To fill my emerging oscilloscope and LA needs, I've not yet ruled out going the route of the PicoScopes and Saleaes. I will likely buy a more traditional benchtop scope initially (of the usual Siglent-ish variety), but I can see myself wanting tools like the former eventually, especially a nice LA for greater convenience in digital projects. It's all about nothavingto (re)build custom tools all the time.For the mini PC to hook these up to, I'm currently looking at fanless design like the Celeron J4125-based 8 gig RAM Mele Quieter2. This compares pretty well to the aging ultrabook I currently have on the table, anyway.But I have 0 experience with the PC performance requirements of USB-based scope/LA solutions. Are these applications (which I'd run on Linux if possible) a good fit to something like a J4125 or should I aim for a more powerful host PC for these?The vendor websites actually don't go into great details, which gives me a general "you'll be fine" vibe, but I'd like to hear from folks with practical experience using this gear.

author: ataradov
author_rank: Super Contributor
timestamp: October 26, 2022, 07:01:43 pm
content: You don't need a lot of performance for PC based scopes. All the fast stuff happens on the device itself. PC is just a display interface. And LAs don't do much work at all, so they should be fine too.It is more about how bloated the vendor software is. If it is some Electron-based monstrosity, then it would be slow even on a fast PC.

author: balnazzar
author_rank: Frequent Contributor
timestamp: October 26, 2022, 07:09:09 pm
content: Quote from: ataradov on October 26, 2022, 07:01:43 pmOk, but the processor he mentioned is very, very slow. If money allows, and the software has a release for the architecture, I'd go for for a M1 mac mini.Otherwise I'd build an Alder Lake i3/i5 mini pc. It can be made almost completely silent.

author: ElectroSone
author_rank: Newbie
timestamp: October 26, 2022, 07:10:06 pm
content: Thanks for your replies so far!This is partly it, I'm not quite sure what the division of labor is between the USB dongle/frontend and the host PC on these types of projects, i.e. how much of the processing happens in for example an FPGA on the product and how much on the PC. Same (or more so even) for the memory requirements for capture/analysis.I guess this is also one of the differentiators between different vendors and price ranges in that space.Just doing napkin math I can see that generally speaking any PC made in the last 15 years scales fine to the raw numbers involved in the hobbyist tier applications, buuut yeah ... being a software guy I also know how you can ruin your performance with badly-written software with very little effort.

author: balnazzar
author_rank: Frequent Contributor
timestamp: October 26, 2022, 07:10:34 pm
content: Quote from: ElectroSone on October 26, 2022, 06:21:10 pmI have a certain number of PCs for sale. PM me if you are interested.

author: ataradov
author_rank: Super Contributor
timestamp: October 26, 2022, 07:25:11 pm
content: I don't know how slow this CPU is. I'd say if it can run MS Word, it would run PC scope without too many issues. I have not used PC based scopes on low end hardware, but I did run logic analyzers on netbooks when that was a thing and it worked fine.But still, for the lab I would suggest to get small, but real PC. There are a lot of other uses for it in the lab.

author: alm
author_rank: Super Contributor
timestamp: October 26, 2022, 08:19:35 pm
content: Quote from: ElectroSone on October 26, 2022, 06:21:10 pmFor LA I would definitely go the PC route, but for scopes the price/performance ratio of the PC-based scopes doesn't seem so great unless you have specific needs or space constraints.On the topic of the PC, if anything PC-based test equipment seems behind the curve. Do any of the < $1000 PC-based instruments support USB standards beyond USB 3.0 5 Gbps?

author: balnazzar
author_rank: Frequent Contributor
timestamp: October 26, 2022, 10:39:25 pm
content: Quote from: alm on October 26, 2022, 08:19:35 pmDepends. My 100$ Owon 1022i 25 MHz usb scope beaten a Rigol MSO5000 in observing microvolt signals. A 200$ Pico 2205 also does pretty good bode plots. Moreover, don't forget that for a usb scope some of the processing happens on the PC. How fast the FFT will be and how often will it be updated, for example, depends upon the PC computing power.

author: BillyO
author_rank: Super Contributor
timestamp: October 27, 2022, 02:51:41 am
content: On your mini-PC, I'd go for something a little beefier than that Celeron. Two years ago I picked up 5 Acer 3 liter PCs with gen5 i5 and i7 processors and all five cost me nothing. These were being thrown out by a veterinary clinic that needed to update for software reasons. All I had to do was erase their HDDs and give them back for auditing purposes. Now they are every where in my house. I did add memory and SSDs to them all, but that cost me very little. In any case, look around for something with a little oomph that will keep you going for a while.There are a ton of USB instruments available but you need solid use cases to determine what you will really need. If you tell us your use cases we can give you better advice regarding the instrumentation, but look locally for bargains on the PC. Even talk to a local mom 'n' pop store, they will have a line on stuff like I stated above. They may charge you a few $$ but it will be cheap and cheerfull.So, let us know what your use case is.