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  1. I’m wondering if I can get by with a logic sniffer instead of an oscilloscope. Can someone please give me advice? Thank you.

    1. What kind of work are you doing? If you;re debugging digital circuits a logic analyzer can be much much more helpful than an o-scope. If you do analog stuff (very fast digital = analog too) then an o-scope is more useful. I personally don’t keep an oscope on my workbench because I use it so rarely.

    2. It really depends on what you are trying to do. The logic sniffer is a nice bit of kit if you want a logic level view of what is going on. But it won’t show you the analog picture of things. So you won’t be able to see, for example, noise on power rails or overshoot on digital pulses, etc. However, if what you need is something to show you what your digital signals are doing, then the logic sniffer is just the thing.
      It is much more useful if your normal project is a simple microcomputer based design. Looking at things like UART or SPI signals or PWM signals for example.

    3. The main difference, after the analog/digital, is about memory: oscilloscopes generally memorize what they can display on their screen, which is a very limited time, while logic analyzers can save much longer waveforms, e.g. a bunch of SPI transfers.
      You will never be able to debug SPI communication with only an oscilloscope without some magic.

  2. With digital scopes being the norm rather than the exception, scopes can usually capture much more than what the screen shows, but the logic analyzer has two big advantages:
    Where a scope usually have 1 or 2 channels, logic analyzers (logic shrimp aside) have at least 8 or 16 channels.
    In addition, smart triggering and the use of mask&match logic can extend the length of time over which the logic analyzer can sample data, by capturing only important data points. A digital scope, on the other hand, once triggered, will continuously sample its analog input signals until its buffer is full.

    1. “much more” is not that much at least for non-expensive scopes: as an example, the tektronix DSO I use daily memorizes 2.5k points, which are 4 “screens”, not that much.
      BTW, the number of channels is another huge difference for sure.

      1. Depends on the non-expensive scope. The one I have by GW-INSTEK, does 2 Meg samples. Has come in handy a few times when I missed the proper trigger. The scrolling can sometimes be a pain and dumping 2 Meg samples to a CSV file takes forever; however the data is there.

  3. Interesting that Ian doesn’t keep an oscilloscope on his bench – I always do, and I turn it on before the DVM (unless I need to measure resistance). I find a quick look at a signal or a power supply enormously helpful.

    I do also have some logic analysers and find the Saleae Logic particularly useful for things like SPI, but if I could only keep one instrument, it would be the scope – and an analog one at that. Modern digitals are great but often you don’t need more than real-time measurement.

    Keeping it on the workbench is important too : it’s one switch away from being used. It’s possible that if I had to get it out of a cupboard, I’d try to manage with the DVM instead (and miss a lot of useful information).

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