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Topic: Scope recommendation? (Read 4042 times) previous topic - next topic

Nonyaz

I'd like to buy a nice desktop scope to troubleshoot my Arduino, but I'm not sure of the minimum specs needed to ensure the scope can keep up with it.  I'm a first year EE student, so eventually I'd like to get a professional scope, but for now I'd just like a moderately powerful one that will handle all these micro controllers with ease.

Any advice would be appreciated!

Osgeld

I have a old 20mhz digital storage scope, and it does fine for the arduino, but it gets limited quickly considering that the arduino's clock is almost at the scope's max
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Nonyaz

I've been researching this all day and I've narrowed it down to something in this series: http://www.tek.com/products/oscilloscopes/mso3000/

I know 100MHz should be enough for the Arduino (They recommend a bandwidth 5x higher than what your working with), but I'd feel better with 300MHz.  Also i'm trying to convince myself I don't need 4 inputs, but they sell an addon that can trigger on serial and I2C packets, and if I get that, I can see myself using more than 2 inputs.

I got some saved searches in on eBay for this series, so I might just wait for a deal to come by.  I'm not going to pay MSRP for any of these.

keeper63

You might want to look at these:

http://www.bitscope.com/

You also need to define what you want to do with the scope; what kind of signals you expect to work with, what voltage levels, etc. If all you ever expect to do with the scope is work with digital TTL signals (for instance), then a logic analyzer may be a better option. If, however, you want to check out, say, NTSC/PAL video signals, or some other complex AC waveform, then a traditional scope may be best.

Something to consider is that you don't necessarily need a ton of inputs (especially if you are starting out), unless you are expecting to do some kind of protocol analysis, or logic tracing, where you need more than say, 2 channels (after 2 "real" channels, the price on a scope climbs quickly - whether in the new or used market). Much can be done with a lower speed (< 100 MHz) 2-channel scope - plus they can be found fairly cheaply on the used market (I recently picked up an analog 2-channel 60 MHz tek scope for $150.00 off craigslist).

Here are some other links, though, for possible scopes:

http://www.saleae.com/logic/
http://www.syscompdesign.com/index.html

Also, look up on ebay and elsewhere the "DSO-2090" and "DSO-5200" USB oscilloscopes - they are both "China Specials", but I have heard some good things about them. They also have driver development under *nix, if that is anything you need.

Finally - there is this scope:

http://www.jyetech.com/Products/LcdScope/eDSO062.php

Don't expect miracles from it, but if all you expect to do is simple troubleshooting of low-frequency waveforms (say, for instance, audio output, or servo ppm troubleshooting, etc) - this can be an interesting scope to play with from what I have read.

:)
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AlphaZeta

I guess it would largely depend on your budget... There are a lot of nice scopes out there that I would like to own, but they are way too expensive.

keeper63

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I guess it would largely depend on your budget... There are a lot of nice scopes out there that I would like to own, but they are way too expensive.


I would be willing to bet that the majority of people on this forum could likely get by with a simple, under-100 MHz, 2-channel analog scope. That would likely cover their needs the majority of the time.

If you need more channels, or some way to save and review the waveform(s), then going with one of the relatively inexpensive PC-based scopes is probably ideal. If you have an idea of what kind of projects you expect to work on (at least in the near-term), that can help you decide the specs for a scope.

In my case, I haven't had a need for a scope, but when I saw the Tek on CL, I couldn't pass it up. For something of that speed, dual-channel, and had been recently calibrated by Tek - it was well worth it. I also knew that the only things I would likely be looking at were possibly servo waveforms, quad-encoder outputs, maybe some audio - things of that nature; so higher speed/bandwidth or more channels just wasn't needed.

Would I pass up a good logic analyzer if I saw it? No - but right now, for what I am doing, I am not seeing the need.

Others may have different needs, though, so they need to keep that in mind. Likely, for most things, a simple scope like I described above, plus one of those Saleae units (or just a bitscope) would cover all likely possible needs.

I also figured, even if I didn't need it immediately, it was better to strike while the iron was hot, instead of waiting longer and then finding out I needed one for a problem and then having to wait to fix the problem until I had one on hand (I don't know anybody local that has one I could borrow).

:)
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AlphaZeta

cr0sh, you are absolutely correct. I guess that even a 2-channel under 100MHz scope can be quite pricy. I have been looking at this scope for a while (http://www.mpja.com/prodinfo.asp?number=17520+TE) but still haven't decided whether I should bite the bullet... I know this is a digital one, but nowadays analog ones are comparable in terms of price and unless you can get a used one from a reliable source, why spend equal amount of money settle on an analog scope?

keeper63

#7
May 18, 2010, 02:09 am Last Edit: May 18, 2010, 02:10 am by keeper63@cox.net Reason: 1
Quote
I guess that even a 2-channel under 100MHz scope can be quite pricy.


Brand new, yes; you'll be sub-$1000.00 - but generally over $500.00, unless you go with a PC USB scope (and even those can get pricey).

Quote
I have been looking at this scope for a while


Something you'll want to do is a lot of research - I don't know anything about that scope, but it looks like a good general purpose or beginner's scope. The fact that it has storage, too is nice; plus the USB interface (wonder what that is about?)...

The bandwidth is kinda on the low side for Arduino stuff (you want something at least 2x - but others say 3-5x - the max frequency in a system you can expect; with an Arduino that can be between 40-100 MHz, depending on who you talk to, etc) - but as long as you aren't trying to scope out super-high-speed signals at the clock rate of the ATMega, it would probably be fine.

Quote
I know this is a digital one, but nowadays analog ones are comparable in terms of price and unless you can get a used one from a reliable source, why spend equal amount of money settle on an analog scope?


I went with the Tek scope I did for a variety of reasons - first and foremost was the fact that it was cheap. But right behind that was the fact it was a Tek and had been recently calibrated by them; on a used scope, I would be very wary otherwise (which is why I wouldn't buy one on Ebay, unless I had a way to calibrate it, which requires equipment - a calibration signal generator - that is also very expensive).

For me, it was a "right price, right kind, etc" choice - I couldn't pass it up. It may not have storage capability, or any number of other options that you can find on other digital scopes, but it was better choice for me than spending the same amount of money on what I could get as a USB scope.

I figure that in the future, if I was going to get another scope (if I ever need one), that I would likely go for a BitScope - they are well known as good USB scopes, plus they have drivers for *nix (I think xoscope supports the BitScope) - which is important to me as I don't run Windows (I keep hoping that Saleae will release a *nix version of their system - that's a nice logic analyzer).

Personally, I think it is likely (and if not, you should set one up) that your lab is going to have a PC nearby, so your tools (scope or whatever) should all interface with that PC, if you can afford to set it up this way. That scope you posted might be a good compromise depending on what the USB interface allows.

Oh - one other thing: Having either a digital scope (like you posted) or a PC USB scope (like a BitScope) does have one large advantage over, say, the scope I picked up: Size. My scope is a bench scope, but I don't really have room on my bench for it. I am going to end up building a cart or something for it; its also nice in that it can stand vertical on feet built into the backside (where the z-input and power cord are) - but it would sure be nice if I could have it on my bench. So there's another item to keep in mind...

:)
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AlphaZeta

Thanks for the input cr0sh! I guess that's what this forum is all about, it's nice to listen to options from different people. I'll certainly keep your advice in mind :)

Cheers!

Osgeld

Quote
Size. My scope is a bench scope, but I don't really have room on my bench for it. I am going to end up building a cart or something for it; its also nice in that it can stand vertical on feet built into the backside (where the z-input and power cord are) - but it would sure be nice if I could have it on my bench.


Bah! I have mine sitting on a 2.5 x 2.5 ft card table that IS my bench  :D

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1268626170/0

http://arduino.cc/forum/index.php?action=unread;boards=2,3,4,5,67,6,7,8,9,10,11,66,12,13,15,14,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,86,87,89,1;ALL

keeper63

I can get mine to sit on my bench if I use the handle to prop it up by about 60 degrees; but then, sitting down, I can't see it...

;D

At that point, it would be better sitting on the floor vertical, but I don't trust myself not to knock it over (sometimes I'm clumsy; sometimes I'm careless).

Right now, though, since it isn't in use, I have it sitting on a shelf.

:P
I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

udoklein

#11
May 18, 2010, 08:51 pm Last Edit: May 18, 2010, 08:55 pm by udoklein Reason: 1
@osgeld: 20 MHz is enough if you prescale the clock. You can do this even in software. Of course it slows down everything a lot so this might not always be an option. If you have an ISP you can fuse for external clock and use another Arduino to slow it down to almost any frequency. I slowed one down to 4kHz. This in turn alows for extraordinary low band width. Especially an Arduino could be used instead of a DSO.

Having said that: by now I own a 100MHz Rigol incl. 16 Channel Logic Analyzer. Not as good as a real professional scope but very much better than what I used to do :)

@AlphaZeta: I decided to not use an USB scope. I still think this was a proper decision. The point is that the USB scope can not run standalone. It has different usability. It is probably tied to some specific OS and may depend on it. I also found the logic analyzer much more helpful than the scope. However this depends on what you are doing. Only digital, mixed signal or mostly analog.

Udo
Check out my experiments http://blog.blinkenlight.net

Osgeld

TBH I have only hit the 20mhz limit of my scope a couple times, and both times it was useable thanks to the analog scaling of the scope, although not 100% accurate, it was more than enough for the job

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