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Using an Oscilloscope — Parallax Forums

Using an Oscilloscope

ComputeruserComputeruser Posts: 16
edited 2013-07-11 05:34 in General Discussion
I read about the Oscilloscope program module on line here. Is there any documentation for using a regular Oscilloscope? I have a Digital Storage Oscilloscope and I can get (but do not yet have) a logic analyzer module for it. I am not sure what it would tell me.

Any resources on the Parallax site about Oscilloscopes would be helpful.

Thank you, ... C

Comments

  • PublisonPublison Posts: 12,366
    edited 2013-07-09 13:52
    Computeruser wrote: »
    I read about the Oscilloscope program module on line here. Is there any documentation for using a regular Oscilloscope? I have a Digital Storage Oscilloscope and I can get (but do not yet have) a logic analyzer module for it. I am not sure what it would tell me.

    Any resources on the Parallax site about Oscilloscopes would be helpful.

    Thank you, ... C

    You can download the text for free!

    http://www.parallax.com/StoreSearchResults/tabid/768/txtSearch/Scope/List/0/SortField/4/ProductID/719/Default.aspx
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2013-07-10 10:07
    This thread is off-topic in the BASIC Stamps forum and is being moved to the General Discussion Forum.
  • ComputeruserComputeruser Posts: 16
    edited 2013-07-10 16:23
    The book linked above is, I think, a purchased book, not a free download. It is not expensive, so that is no problem. The write up pitches it at a basic level and I have (and know how to use) a Digital Storage Oscilloscope, a decently fast Function General, a good DVM and other assorted gear.

    I can reframe my original question a bit.

    If I have a Basic Stamps OBE-BOT running and working, is there any use for an Oscilloscope for working with the Stamps module? I do not see any, nor any references (save for the one above) that might help me.

    I can get an 8 channel Logic Analyzer for my Oscilloscope. Does that buy me anything? I don't think so.

    Please let me know if you see value and use that I do not yet see.

    Thank you, .... C
  • PublisonPublison Posts: 12,366
    edited 2013-07-10 16:34
    Computeruser wrote: »

    Please let me know if you see value and use that I do not yet see.

    Thank you, .... C

    The book can be downloaded here:

    http://www.parallax.com/Portals/0/Downloads/docs/prod/prop/32220GettingStartedv1.0.pdf

    General information on the Propscope can be found ofn the product page :

    http://www.parallax.com/go/propscope
  • prof_brainoprof_braino Posts: 4,313
    edited 2013-07-10 18:17
    Computeruser wrote: »
    I can get an 8 channel Logic Analyzer for my Oscilloscope. Does that buy me anything? I don't think so.

    An oscilliscope can show you something about the way a pin (the input you are reading or the output you are producing changes voltage level in a particular period of time. Its like a fancy high speed volt meter.

    A logic analyzer is similar, but focuses on the change of logic levels as either 1 or 0, hi or low.

    If you want to see something about logic analyzer, and have a prop, you can use the software logic analyzer in propforth. Its a small program that runs on one cog of the prop chip , and tells you the logic level of the pins connected to the prop 32 chip pins (so its 32 channels for free). If a prop is cheaper than the logic analyzer module it would be a good way to start.
  • ComputeruserComputeruser Posts: 16
    edited 2013-07-10 18:42
    I need to do some more testing with a running program to see where/if I can see voltage changes on the module. I might try probing the servos as there are a lot of changes there. But overall it is not very revealing (at least so far). There is more to see in the frequency modulation for my Digital Command Control model railroad.

    I have to decide about the logic analyzer. It is decent value as it is a module that plugs into the front of the oscilloscope, but it is not cheap, even though good value.

    .... C
  • evanhevanh Posts: 15,943
    edited 2013-07-11 05:25
    A logic analyser shows timing between multiple logic signals. Compared to, say, a deep capture scope, they're very good at that job simply because of being able to hook up so many more signals at once.

    But, they're not capable of showing the shape of the signal and will usually have limited voltage range, so one has to keep this in mind when troubleshooting.
  • GadgetmanGadgetman Posts: 2,436
    edited 2013-07-11 05:34
    Some Logic analyzers can also analyse the pattern and try to match it against known protocols and read out data in the signal.
    So if you think you have i2c, SPI, RS232 or something, you can verify that.

    More advanced is debugging functions. Some can be hooked up across the data-bus on a CPU and disassemble the code being read by the CPU.
    Even more advanced(requires 16 or more inputs) is the ability to connect it across the Address-bus of a CPU and get a graphic showing where in ROM/RAM it's executing code, in realtime.
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