I'm trying to figure out what this tool is, to use it as an oscilloscope. I found it here.
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3 Answers
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This image is from Saleae Logic 1.
Saleae logic analyzers have an oscilloscope function, but frankly this is not very good except for low speed, imprecise measurements. It is a decent logic analyzer for low-speed busses like I2C and SPI (if not too fast).
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1\$\begingroup\$ @kovac Well, Saleae have several models on the website (click the link above). I think this is a fine product, if you understand the limitations. It is compact, and relatively easy to use. As to which model, that comes down to your budget. Your choices are $500, $1K, $1.5K. You get more features for more money. Does that help? \$\endgroup\$– TroutdogJun 2 at 20:46
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That looks like a logic analyzer, which is similar to an oscilloscope except:
- It's designed for digital signals only, meaning it only shows high or low, not any levels in between or any overshoot/undershoot
- It usually has many more channels--typical LAs have 8 or 16 channels, while more than 4 channels is a luxury on an oscilloscope
More and more oscilloscopes these days have logic analyzers built in, too. These are referred to as mixed-signal oscilloscopes, and they typically have four traditional analog oscilloscope channels and sixteen digital logic analyzer channels.
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1\$\begingroup\$ There's an increasing number of hacks using an FPGA or e.g. the RP2040 that provide this sort of facility, and I think I've seen at least one that allowed daisy-chaining to support more inputs. However the "legacy" logic analyzers still have a lot going for them: I've got an old HP as a fallback with ~65 channels, 10 nSec resolution, and inputs safe for +-40V. \$\endgroup\$ Jun 1 at 7:47
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\$\begingroup\$ The adoption of high-speed serial interfaces for many things has pretty much rendered those old-school LAs obsolete (in my experience). SERDES analysis is more analog in nature, and is best done with a high-bandwidth oscilloscope. I will say, however, that I miss the sophisticated triggering you can do with those older LAs. \$\endgroup\$– TroutdogJun 1 at 14:28
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\$\begingroup\$ @Troutdog I'm afraid I've never had cause to use a logic analyzer; I work almost entirely with analog circuitry, doing power supply design and bespoke test fixtures. So I'm not really aware of what is and isn't useful about them these days. \$\endgroup\$– HearthJun 2 at 0:42
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\$\begingroup\$ @Troutdog Yes, but that's basically down to the firmware in the analyser. The current situation appears to be that all of the work is being done in two places: (proprietary) 'scopes with LA functionality, and PC applications such as PulseView and Saleae (open- and closed-source respectively). But while a modern 'scope obviously has speed and protection at least as good as the old analysers, older kit can still be extremely useful if you want to look at a substantial number of signals simultaneously (e.g. an Arduino etc. on a "bed of nails"). \$\endgroup\$ Jun 3 at 9:08
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You can download the software and run it in demo mode to see what it can do or not do for your needs.
To clarify the general comment about LA not supporting analog (which was certainly true in the past but only sometimes today). However, the Saleae pictured by the OP has both analog and digital channel support (they are configured in SW to be one or the other at capture time). There are also quite a few other decoders available for serial protocols (also as shown in the image) and an API to add your own filters, automation and decoders, etc... All of these seemed specifically relevant to the OPs question and image post.
Here is a breakdown specs and you should read them carefully as they have clear limits like the analog side has a pretty narrow bandwidth and the lower end unit LA digital is only supporting 0-5V:
https://usd.saleae.com/products/saleae-logic-pro-16
I have no affiliation with the company. I am just an IT guy and this is a hobby I share with kids. I have had one of the 8 channel products for a couple of years and found it was good for some things, but not so good for others but it was an affordable limited LA that worked better than the analog Tek scope and for more channels.
Originally there was no real time display. Being inexperienced in LA usage I found that very limiting and didn't use it much until the software was upgraded and allowed for that type of live display while capturing (hence the constant SW development portion of the original comment).
My intent is just encouraging the OP to give it a try in demo mode and see what it was like. More exposure to a variety of tools and their capabilities would be of benefit on someones learning path.
