Triggering and scope view - share your ideas with us!

agree on all points, but add “trigger when 0/1 for time t” which is useful for finding things like horizontal sync on video signals and bit slicers.

Can you please elaborate? Why are you trying to find these signals?

p.s. welcome to our forum! :slight_smile:

1a. lots of 1-wire protocols (SPDIF for example) wiggle the wire like crazy, but you you know when you’ve reached the “start” of a digital packet when you get a “1” for any time > N microseconds. This would allow the trigger to sync to the beginning of a packet.
1b. Analog video signals utilize a “framing” mechanism to start the TOP-OF-FRAME and START-OF-LINE to indicate the first pixel of the frame and the first pixel of any scan-line. In these moments they hold the output high or low for > N microseconds. So you could get a plot (google composite video on scope) to see what I mean.
2. Fast-refresh X/Y Plot would outrageous, but it’s a “nice to have”

  1. Generally I agree on all request for a fast refresh and triggered window on arriving ADC data.
    3a. Trigger on rising / falling / both edges, setting a trigger voltage
    3b. Trigger-delay to slide the trigger point left/right on the screen.
    3c. (persistence / decay) This shows the “history” of the signal and older traces decay to black (google eye-diagram) Useful for testing signal integrity / clock jitter.
    3d. Trigger enable: one-shot, continuous
    3e. (NEW: not done on scopes today) Stop acquisition and [step left / step right] through all the triggering traces. Useful for finding that “one glitch” that zipped past two seconds ago.

Frankly, I think the “first demo” needs to have (the 80% of the 80/20 rule)

  • FAST refresh plot based on a rising/falling trigger
  • user sets trigger voltage, X scale, Y scale and adjusts the trigger voltage and (one-shot, continuous)
    Note: this demo DOES NOT need to record everything, it’s perfectly fine to hold relatively small buffer and cycle through it. There is not a “capture everything to disk” requirement.
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Thanks a lot! This is super helpful :slight_smile:

One thing that I noticed is that most people mainly talk about the visualization level, i.e. show me the data and I’ll figure out what the issue is, and not in an analysis level - for example, measure if the signal is valid, calculate signal metrics after the trigger, etc. I feel like the analysis level barely exists today and there is a lot to do there (but maybe I’m wrong). I’d love to hear what others think about that.

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I believe the reason for that is because it takes MUCH longer to “train” the analyzer on sophisticated signals. These have good use in manufacturing lines, but nowhere near as much on the lab bench.

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Analyzers are incredibly domain-specific. What’s perfectly ok on a serial port would be a critical failure in other logic. Generally they’re packaged (as analyzer configs) to meet one domain’s needs.

Of course, it means that we need to build tools that you can quickly configure for your use case.

Well I’d prioritize it after a fast-refresh triggering display. IMO that’s part of the 20% and it would only get used if it had a bundle of useful configs I could use without “training”

The reality is, especially on mixed-signal stuff, that you “notice” things that don’t look right the first time you see them. The concern with an analyzer is it would either A. be silent when you know there’s a problem, or B. be screaming FIRE when the signal is fiine.

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I agree with @Pat: “Analyzers are incredibly domain-specific”. Humans are pretty good at spotting patterns and deviations from patterns so letting the mark 1 eyeball do the initial heavy lifting makes good sense.

Providing the tools to allow users to then build their own analysis systems when and as they are needed is where I think Saleae should focus. A great example of that is the HLA API. That has been fantastically useful to me with my current project. But the HLA I’ve developed is too specific to our hardware to be directly useful to anyone else.

Some of the suggestions in the pipeline such as providing analog data to HLAs and generating analog trace data from HLAs are likely to be much more useful to users than trying to provide domain specific answers.

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Replicating the basic features of an oscilloscope would be tremendous. My use case for oscilloscopes is mostly leaving them running while I swap parts in and out on a breadboard. This sort of interactive use is infeasible without live display. For this, I don’t need any measurements, only the visual display.

Since you asked about aspects where Saleae could go beyond traditional scopes, I’d first like to say that 8 channel scopes cost as much as a car and 16 channel might not even exist (if they do, they’d cost as much as a house).

And then there is memory depth. This is where Saleae really pulls ahead of scopes. Two of the items Pat mentioned, 3c (decay) and 3e (step through history), could be combined. That is, you have a slider that chooses the n^th capture to be brightest, and the captures before and after that are progressively dimmer. I think this would be visually striking and could end up being useful. For instance, you could easily see whether the captures before and after a glitch were abnormal, and you could see how a signal has drifted over time. These captures should be timestamped.

The XY display on my entry level Rigol is terrible. I think there are two reasons: low memory depth and a gap between captures. I could see making a very nice XY plot on the computer. In fact, it could even be an XYZ plot you could rotate in 3D. I don’t think anybody else does this. I can’t name a use case, but I’m sure it’d get used. XY plots are for things like voltage vs. current, or voltage into a filter vs. voltage out. A third channel here is useful for the same reasons it’s useful elsewhere. Or, if not 3D, it could be plotting XY, YZ, and XZ. Of course, this is gravy. The biggest benefit will be from the traditional basic scope features.

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Yes! I think you’ve hit the nail on the head - to me, in my normal usage, a scope is for exploring/visualization. Then, if I need more detailed analysis, I turn to the Logic. That’s why the scope display needs to be responsive and quick, without needing to set up too many things first. I just want a ‘real time’ view of what’s going on wherever I am probing.

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XYZ plots would be insanity, I think I could come up with some uses:

not an incredibly practical use for XY plots, but check out Jerobeam’s Youtube channel:

I kept my ancient raster oscilloscope around just for this music.

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Providing the tools to allow users to then build their own analysis systems when and as they are needed is where I think Saleae should focus.

I completely agree. That’s why we built the marketplace and that’s why we’re having this discussion :slight_smile:

The more we understand your workflows (and your bugs), the better we can build that infrastructure. We would also like to organize a meetup soon to share our plans and hear your feedback directly.

One of the killer features of Saleae is that I can leave it running for hours and capture all the data. However, sometimes when you’re looking for something very specific, that can be cumbersome. I would love to see some kind of “fast segmentation”. Based on a trigger, capture x seconds after that and keep capturing in the same windows for x seconds eveytime that trigger happens. Of course this is very useful when trigger can have advanced features or be coupled to decoders.
For example: trigger every time this signal remains high or low for x time or when uart sends this string, etc.
I agree that saleae shouldn’t strive to be a scope, but can certainly benefit from scope features.

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First of all, I really enjoy your product, and I think the way you are going with HLA and openness with respect to the API is perfect. I did not write a HLA, but I might start in the nearer future.

When it comes to features that I would find extremely useful (but have not found), it would be the ability to load/import/compare/merge all (or specific) channels from multiple captures. Right now, I am trying to make sense of SPI captures of multiple devices (at multiple “strategic” times), where I am not sure if the devices are working properly or not. It would be awesome to be able to correlate, say, MOSI and MISO channels of multiple captures. I am working around this by multiple instances of Logic 2, but actually finding where the differences are is a bit clumsy (scrolling has to be performed in both instances, …)

It might be already enough to overlay one capture with another, “reference” capture (think reference waveforms from digital storage 'scopes). I must admit that I haven’t fully thought this through, but in the digital domain there may even be more opportunities (diff calculations, …), albeit I have to admit that I wouldn’t know what to do with it (and we could always export the data and feed it to external diff tools).

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Snap. Comparing captures is something I’ve been thinking about too and I’m running two instances of Logic2 right now for exactly that purpose. It seems to me to be a really hard problem to solve - even harder than a good text diff tool, but with many of the same problems.

The first major problem is being able to time align different parts of the captures because most real signals will have subtle or significant variations in the timing of interesting events. Maybe that means being able to slice one of the traces into chunks so different chunks can be aligned with different portions of the reference trace?

Comparing SPI (or whatever) analyzer text output for the two traces could benefit from standard text diff processing and depends less on time. That may be a quick way in a lot of cases to identify areas of interest. Being able to highlight trace areas that map to text differences and align them in time could be quite powerful.

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Now that I looked a bit deeper through some of the captures, I noticed a few “spikes” where I’m not sure if it’s something that the DUT does or if it’s a glitch-response of the Logic 8 Pro.

For this, I propose two things:

  1. Find/mark outlier events (e.g., the clock, I think, would be mostly stable with respect to frequency/duty cycle for one capture). Those cases where the clock signal “glitches” potentially might be interesting to look at, especially if it’d change the way the protocol analyzer might treat the data. From a certain zoom level, the little triangle markers could be used to find mismatches/anomalies, but for a longer-running capture (a few seconds is already enough), it’s a bit tedious to scan through the entire thing just to spot those. Maybe it would be great to pin those occasions where the frequency exceeds a certain multiple of its standard deviation or something like that. If that’s possible with a HLA I might whip something up for it. I don’t think any of my 'scopes could do this.
  2. Display dots of analog channels instead of “just” an interpolated wave. I reckon I could’ve used the scope to detect if the glitch “was real” (i.e., caused by the DUT) or if it stems from the way the Logic 8 Pro reacts. Knowing when exactly what values were sampled would help me, or at least that’s my conception/hope :slightly_smiling_face: The option to switch view in the analog channels would be great.
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Find/mark outlier events

Features like this could really help debugging if they are done well imo - Auto-detection of analyzers and their settings, diffing two channels, and more.
I don’t think that you can implement it with HLAs, but you can do that with a measurement extension.

See (and add your vote) https://ideas.saleae.com/b/feature-requests/display-analog-samples-with-dots-as-well/

Some of us are quietly hanging out for that :grin:

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It would be really nice to have basic analog math functions - add, sub, mult, inv.

Also - FFT would be really cool, at least for audio spectrum if not higher.