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Thread: Oscilloscope and function generator for robotics research

  1. Re: Oscilloscope and function generator for robotics research

    Keysight used to be Agilent, it's a well known and respected brand. Never heared of GWINSTEK before. So your choice...

    Is 70MHz sufficient for advanced robotics research?
    Depends on you. You can do a lot of stuff with a 20Mhz scope, or you could be limited by a 500MHz one, depending on what you do.
    Usually, if you do not know what you need (which seems to be the case), then you don't need anything faster.


    I have a Logic Pro 16, and in many cases the analog functionality has been extremely useful (like when working on ADC and DAC code, or for monitoring power when specific events happen on communications lines), but the analog bandwidth is quite limited (5MHz) so it definitly can't replace a real scope for me. As soon as you have something that goes faster than an Arduino (I currently use Cortex M4 MCUs in the 50 to 120 MHz area), a 200MHz scope comes in handy.
    Also, even in USB3.0, downloading the analog data is painfully slow.
    Basically it's an incredibly good tool for analyzing complex anlaog signals (<5MHz) alongside digital signals, but not suited for real-time adjustments / analog event capture / general troubeshooting.

    You could also simply get a Rigol DSO1054 for about 400 USD and have a look around on the internet what you can do with it.
    I personally have a Rigol MSO1074Z (70MHz), and it's bandwidth is showing its limitations too when I try to track relatively high-speed problems (pin toggling on a 120Mhz MCU for example). Friend of mine got the DSO1054 and "upgraded" it to 200MHz, works like a charm.
    ---
    Personal blog: http://xevel.org
    USB2AX documentation: http://xevelabs.com

  2. Re: Oscilloscope and function generator for robotics research

    Quote Originally Posted by Xevel View Post
    Keysight used to be Agilent, it's a well known and respected brand. Never heared of GWINSTEK before. So your choice...

    Depends on you. You can do a lot of stuff with a 20Mhz scope, or you could be limited by a 500MHz one, depending on what you do.
    Usually, if you do not know what you need (which seems to be the case), then you don't need anything faster.
    I think GW-INSTEK is a Taiwanese company. I have used Agilent products at school before. They are quite good. I guess one advantage of using the Agilent is that the specs could be upgraded later.

    These days, some Chinese companies also make quality products. How about Rigol?

    I plan to use the scope to test some circuits. In case I use your usb2ax, ArbotiX Pro, the latest Ordroid, Raspberry Pi 3, arduino, robotis controllers and dynamixels to build robots, which of the following would be recommended and future proof?

    DSOX2012A (100MHz, 1Mpts, 2GSa/s, 2 channels)
    DSOX2022A (200MHz, 1Mpts, 2GSa/s, 2 channels)
    DSOX3012T (200MHz, 4Mpts, 5GSa/s, 2 channels)

    Perhaps get the 2 channels version first and if I really need more channel later, upgrade. The DSOX3 series cannot be upgraded to more than 2GSa/s. Not sure if the DSOX3 series is overkilled.

  3. #23

    Re: Oscilloscope and function generator for robotics research

    Those are very nice! And very pricey!

    You are unlikely to need more than 2 GSa/s for anything robot related, so sticking with DSOX2 is fine, if you can afford it. As Xevel said, up to 200 MHz may be useful if you run very fast SPI bus traces and such. (But then again, those traces are also doable on a logic analyzer, unless you are specifically suspecting analog signal quality issues.)

    Or you can start with an oscilloscope at 1/10th the cost (like an Owon or Rigol,) and then pay for a better scope once you need it.

  4. Re: Oscilloscope and function generator for robotics research

    Quote Originally Posted by jwatte View Post
    Those are very nice! And very pricey!

    You are unlikely to need more than 2 GSa/s for anything robot related, so sticking with DSOX2 is fine, if you can afford it. As Xevel said, up to 200 MHz may be useful if you run very fast SPI bus traces and such. (But then again, those traces are also doable on a logic analyzer, unless you are specifically suspecting analog signal quality issues.)

    Or you can start with an oscilloscope at 1/10th the cost (like an Owon or Rigol,) and then pay for a better scope once you need it.

    Thanks. Is Logic Analyzer (LA) = data logger + more?
    Am I correct that the LA of Oscilloscope only take 0 and 1 but the Logic Pro 16 can take all 16 analog trains of analog signals if I want?

    The DSOX3 now comes with a 16-channel LA at the cost of the DSO. Not sure if it is a good deal.

  5. #25

    Re: Oscilloscope and function generator for robotics research

    A logic analyzer reads signals as "0" and "1" but has many more channels of input. It typically also allows you to configure the semantic meanings between the signals, so you can get byte values out of an SPI bus, and such.
    I find it very hard to make a recommendation, because I don't understand what your pricing constraints are.
    If you have unlimited budget, you will get some marginal additional utility from any high-end equipment you can find, assuming you have the skill to use it.
    If you have to be smart about spending your money, a cheap scope and a Logic Pro 16 is a much smarter way to spend less money for hobby robotics than a $4,000 DSO.

  6. Re: Oscilloscope and function generator for robotics research

    jwatte is spot-on.
    I will also add that a MSO scope (mixed signal digital oscilloscope) is way less practical to use as a logic analyzer than a dedicated USB one like the Saleae Logic. With my MSO1074Z-S, I found that the logic analyzer part is annoying to use at best, and that it radiates noise all around with its long ribbon cable.
    Decoding is also less flexible on a scope than on a good old computer.
    If I had to choose now, I would get a DSO1054Z (400 USD) and a Saleae Logic Pro 8 (480 USD), then upgrade the scope to 100MHz. That would have gotten me the same level of functionality that I have today for ~1/2 the price.
    ---
    Personal blog: http://xevel.org
    USB2AX documentation: http://xevelabs.com

  7. #27

    Re: Oscilloscope and function generator for robotics research

    As I mentioned earlier, I use my Saleae logic Analyzers (have 3 now including Pro 8), needless to say I like them. I don't have a decent scope. The only thing I have was some digital learning system setup by Parallax, which is real old now and stuffed someplace in cabinet. It is nice to have the analog capture capabilities of the newer ones, but the majority of the time I turn that off as more often then not, I mainly want the digital capture, to help figure out logic issues including looking at different protocols. Including Dynamixel with the analyzer that r3n33 started and enhanced...

    But if you want something on the cheap, you might look at the Teensy forum posting: https://forum.pjrc.com/threads/32205...Logic-Analyzer

    And with his recent posting:
    Version 3.2 release has full support for Teensy 3.5 and 3.6. Teensy 3.6 can go up to 120 MHz, 2 million samples for a single channel.

    Also adds pre-built releases for Windows and Linux - a complete Logic Analyzer application running in 3 easy steps.

    https://github.com/LAtimes2/TeensyLogicAnalyzer
    For those who missed the kickstarter, looks like you can now pre-order T3.6 (http://www.pjrc.com/store/teensy36.html) for $29.25 expected to ship early October (right after the Kickstarter boards ship).

    Sorry for shamelessly plugging both Saleae and PJRC

    Kurt

  8. Re: Oscilloscope and function generator for robotics research

    Quote Originally Posted by Xevel View Post
    jwatte is spot-on.
    I will also add that a MSO scope (mixed signal digital oscilloscope) is way less practical to use as a logic analyzer than a dedicated USB one like the Saleae Logic. With my MSO1074Z-S, I found that the logic analyzer part is annoying to use at best, and that it radiates noise all around with its long ribbon cable.
    Decoding is also less flexible on a scope than on a good old computer.
    If I had to choose now, I would get a DSO1054Z (400 USD) and a Saleae Logic Pro 8 (480 USD), then upgrade the scope to 100MHz. That would have gotten me the same level of functionality that I have today for ~1/2 the price.

    I have seen some very nice videos of the Saleae Logic Pro. Thanks all for the suggestion. I am now considering Keysight and scopes from other companies. Keysight has a special offer of getting MSO at the price of DSO if the scope is 3000XT or above. If I buy the 3000XT, that may be a good bargain. Even with that, the Saleae Logic Pro is still better?

  9. Re: Oscilloscope and function generator for robotics research

    If you have $3k to get a 3000XT, then why not get both tools?
    ---
    Personal blog: http://xevel.org
    USB2AX documentation: http://xevelabs.com

  10. Re: Oscilloscope and function generator for robotics research

    Quote Originally Posted by Xevel View Post
    If you have $3k to get a 3000XT, then why not get both tools?
    I have been thinking about this. If the MSO in even the 3000XT is not as good as the Saleae Logic Pro, then there is less motivation for me to get such an expensive oscilloscope.

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