What oscilloscope specs do I need for Arduino projects?

[wizard69]

This thread is most interesting but I think people are missing one important point, we are talking about somebody new to electronics.    The reasons I suggest a used scope isn't so much because it would be analog (there are used digital scopes) but rather that it is a low cost investment that allow learning.    In the end when somebody gets into this as hobby the direction that hobby might take is unknown at the start.    For example if one gets into robotics, CNC or other technologies that involve higher power circuits, there might be a need for a scope with isolated inputs.

So in short it is far better to hold off buying anything that is going to hit the budget significantly until you have a better idea as to what you need as a tech/engineer.    It is very easy to throw away a lot of money on an expensive instrument that doesn't really fit ones need.   This is why I think it is better to develop the knowledge to make a good purchase than to rely upon suggestions that reflect somebody else's interests.   Thus the suggestion about a used analog scope (really any used scope that can be had dirt cheap) is more about learning about what you need at the lowest possible cost.   Once somebody knows what they need it is far easier to understand the suggestions being made here. 

[tggzzz]

This thread is most interesting but I think people are missing one important point, we are talking about somebody new to electronics.    The reasons I suggest a used scope isn't so much because it would be analog (there are used digital scopes) but rather that it is a low cost investment that allow learning.    In the end when somebody gets into this as hobby the direction that hobby might take is unknown at the start.    For example if one gets into robotics, CNC or other technologies that involve higher power circuits, there might be a need for a scope with isolated inputs.

So in short it is far better to hold off buying anything that is going to hit the budget significantly until you have a better idea as to what you need as a tech/engineer.    It is very easy to throw away a lot of money on an expensive instrument that doesn't really fit ones need.   This is why I think it is better to develop the knowledge to make a good purchase than to rely upon suggestions that reflect somebody else's interests.   Thus the suggestion about a used analog scope (really any used scope that can be had dirt cheap) is more about learning about what you need at the lowest possible cost.   Once somebody knows what they need it is far easier to understand the suggestions being made here.

I fundamentally agree, with the proviso that it is a working scope. See ,for example, my previous post.

There as many vocal people that disagree, and "push" modern digitising scopes.

[rstofer]

There as many vocal people that disagree, and "push" modern digitising scopes.

Alas, I'm one of them.  Although I have that Tek 485 and built my first analog scope from plans in the ARRL Handbook clear back in the late '50s, I view analog scopes vs digital scopes the same way I view the slide rule versus the HP48GX.  I got through undergrad with a slide rule, I still drag it out from time to time, but I actually use a calculator.

I don't agree that there is anything special to learn from an analog scope.  The primary controls (V/div, t/div, position, trigger type/level) are the same on any scope.  But the digital scope brings so much more to the game and, in particular, Single shot capture.  In either case, the learning curve is going to be about the same but there is so much more capability with the modern DSO.

A used, but  working, analog scope may fill a financial check box but that would be one of only two reasons for buying such a thing.  The other being bandwidth.  It's pretty easy to find a Tek 485 350 MHz scope for a couple of hundred bucks, plus a bunch for shipping.  In the end, it's a great analog scope with a bunch of bandwidth, plenty of features and not a bit of measurement capability.

I'm not sure what the resale would be on a used (again) analog scope but I'll bet the digital will hold its value pretty well.

Today, on eBay, there are a couple of 485s  One is about $200 plus $24 shipping and the other is refurbished, warranted and calibrated for about $500 and $50 shipping.  At the same time, on Amazon, the Rigol DS1054Z is $349 with free shipping.  Kind of in the middle of the cost range between a dubious 485 and a known working/calibrated 485.

If the money isn't there for the Rigol, so be it.  But under no condition is the used analog going to compare with a modern DSO - particularly a 4 channel DSO.  And the resale on the Rigol is going to be around $315 according to eBay.   Not a bad deal if things don't work out in electronics.

And the new DSO works, has a warranty and probably doesn't need a lot of capacitor replacements.  And if you need one of the unobtanium custom ICs, you are just out of luck.

I simply don't see the justification for a used analog scope.  I have one, it works very well, I'm not going to junk it but I actually use the DSO.

[rstofer]

So in short it is far better to hold off buying anything that is going to hit the budget significantly until you have a better idea as to what you need as a tech/engineer.    It is very easy to throw away a lot of money on an expensive instrument that doesn't really fit ones need.   This is why I think it is better to develop the knowledge to make a good purchase than to rely upon suggestions that reflect somebody else's interests.   Thus the suggestion about a used analog scope (really any used scope that can be had dirt cheap) is more about learning about what you need at the lowest possible cost.   Once somebody knows what they need it is far easier to understand the suggestions being made here.

I'm pretty dense, I want to see a picture!  Understanding circuits, to me, requires visualization and simulation doesn't count.  I want to take measurements, with a DMM certainly, but also with a scope.  If I can't see it, I won't really understand it.

I remember pencil whipping Bode' plots in undergrad.  That's not nearly as satisfying as see a plot using the AD2.

Frankly, for the Arduino user, the Analog Discovery 2 is a better choice than either an analog or digital scope.  The 16 channels of digital IO with protocol decoding is a pretty slick feature.  Having a 2 channel scope and 2 channel arbitrary waveform generator brings more capability.  We all understand how PWM works but it's even better to see it in motion.  Then there are the punch-through problems of a discrete H-bridge...  Timing is everything!

If I'm going to use I2C from a uC, it is absolutely guaranteed that it won't work right out of the box.  That protocol is a PITA to get working.  SPI isn't nearly as difficult but you want to be certain the last bit has shifted out before raising CS' in software.  How do you PROVE that if you can't see it?  You can pretty much guess how I KNOW that this  is a problem.

I can't imagine trying to do uC projects without a scope.  A logic analyzer is very helpful, and a lot cheaper, but a scope is my primary tool.  The fact that the modern DSO can do decoding is just icing on the cake.  Let's not forget Single trigger mode!

If I were a newcomer having no equipment and no apparent path, I would buy the AD2 to handle measurements and something in terms of a power supply. There are plenty of used HP power supplies on eBay.

[james_s]

I simply don't see the justification for a used analog scope.  I have one, it works very well, I'm not going to junk it but I actually use the DSO.

The justification is when you can get them for <$100, sometimes much less, I've received several of them for free and given away at least two. They're not as common as they used to be but they are still out there and occasionally burn up. If the price is right, an analog scope can get the job done. No way I'd pay $500 though, not even for a high end low hour unit in excellent condition. If the price is right and funds are limited, you do what the budget allows.

Or if you have a specific need for XY mode, that's one of the few reasons I pull out my 465 anymore, XY mode on an analog scope blows away XY on any DSO I've tried but that's a pretty niche use case.

[rstofer]

I simply don't see the justification for a used analog scope.  I have one, it works very well, I'm not going to junk it but I actually use the DSO.

The justification is when you can get them for <$100, sometimes much less, I've received several of them for free and given away at least two. They're not as common as they used to be but they are still out there and occasionally burn up. If the price is right, an analog scope can get the job done. No way I'd pay $500 though, not even for a high end low hour unit in excellent condition. If the price is right and funds are limited, you do what the budget allows.

If the money isn't there for a DSO, so be it.  Any scope is better than none. 

What isn't justifiable is the idea that there is some kind of 'right of passage' or superior 'learning experience' derived from an analog scope.  They are dinosaurs (other than bandwidth) and should be left in the tar pits.  Including mine.

Or if you have a specific need for XY mode, that's one of the few reasons I pull out my 465 anymore, XY mode on an analog scope blows away XY on any DSO I've tried but that's a pretty niche use case.

I have a pretty specific XY use case when I want to watch the output of an analog computer.  The X axis will be driven by an internal sweep generator and the y axis by the output of the differential equation.  I use it all the time on my DS1054Z and it works very well.  But that's my use case, others may have a different experience.

[tggzzz]

If the money isn't there for a DSO, so be it.  Any scope is better than none. 

Precisely. Even a digitising scope is better than none

What isn't justifiable is the idea that there is some kind of 'right of passage' or superior 'learning experience' derived from an analog scope.  They are dinosaurs (other than bandwidth) and should be left in the tar pits.  Including mine.
 use case.

The point in favour of a working analogue scope is ease of learning and a more gentle learning curve.

Anything else is bunkum.

[Mr. Scram]

The point in favour of a working analogue scope is ease of learning and a more gentle learning curve.

Anything else is bunkum.

As others have noted before, the learning curve on either analogue or digital oscilloscope is already flat as can be. It's not a complicated instrument to get started with. The only exception I see is getting a broken unit or just a flat out terrible one like one of those DIY kits. Any not-horrible two channel oscilloscope in reasonable condition you can get your hands on will do.

[tggzzz]

The point in favour of a working analogue scope is ease of learning and a more gentle learning curve.

Anything else is bunkum.

As others have noted before, the learning curve on either analogue or digital oscilloscope is already flat as can be. It's not a complicated instrument to get started with. The only exception I see is getting a broken unit or just a flat out terrible one like one of those DIY kits. Any not-horrible two channel oscilloscope in reasonable condition you can get your hands on will do.

In my experience, having introduced several groups of amateurs to scopes, the curve is flatter on an analogue scope.

The principal reasons are:

• all tweakable controls and their settings are visible on an analogue scope's front panel
• digitising scopes have more things that can be tweaked, and in some cases need to be tweaked - and therefore explained and understood
• digital scopes have controls hidden, in layers of a menuing system
• all digital scopes vary subtly from each other, in terms of menuing system, cryptic screen icons, and even terminology - which makes it more difficult to swap from one digitising/digital scope to another

All of those points are surmountable, but they cause a steeper learning curve for beginners.

[tautech]

A scope is a scope is a scope !
They all do the same things and their only difference for the beginner is the UI, be it with knobs, buttons, mouse or a touch display.
One overlooks how little settings info is displayed on a CRO yet most DSO's offer substantial settings info on the display so in screenshots we can see what the beginner might be doing wrong and advise them appropriately.

OTOH a CRO must have a pic taken of the whole instrument to examine settings and in such a way to see if knobs are pulled or pushed. 

The beginner is much better served with a modern DSO to come to the forum or their mentor for advice.

[rstofer]

And let's not forget the "Auto" button.  It may well be that the scope powered up with settings you saved months ago and have long forgotten.  Rather than hunt down all the possibilities, push "Auto" and everything will be fine.

I know the pros don't like the feature but I find it quite useful.  Not only do I get a trace somewhere on the screen, it might actually be pretty close to what I want.  A little tweaking of V/div and t/div and I'm there!  Maybe move the position a bit...

Even analog scopes have a "Beam Finder" button to prove that they can draw a line on the screen.  Unfortunately, the line is totally unrelated to the incoming signals, they can still be way off screen.

[Mr. Scram]

In my experience, having introduced several groups of amateurs to scopes, the curve is flatter on an analogue scope.

The principal reasons are:

• all tweakable controls and their settings are visible on an analogue scope's front panel
• digitising scopes have more things that can be tweaked, and in some cases need to be tweaked - and therefore explained and understood
• digital scopes have controls hidden, in layers of a menuing system
• all digital scopes vary subtly from each other, in terms of menuing system, cryptic screen icons, and even terminology - which makes it more difficult to swap from one digitising/digital scope to another

All of those points are surmountable, but they cause a steeper learning curve for beginners.

That's essentially the same point worded in slightly different ways. Even if there were to be some advantage to quite simple versus somehow simpler, it seems to be quickly overtaken by digitizing oscilloscopes being simpler in the sense that they just hand the data to you instead of having to count graticules or inferring it in other ways. No Auto button either. And again, the menu argument seems to stem mostly from people not being used to it. If you watch a teen using an Apple device you'd quickly find that they have no trouble with those at all, despite endless gestures and obscured functions.

Not that it all matters much, the argument seems to be whether it's easier to learn to eat an apple or a banana. People can figure it out either way. Just getting the Arduino tool chain set up tends to be many times more complicated.

[rstofer]

Buying a CRO is simply deferring the cost of a DSO at the extra cost of the CRO.  The new user WILL be buying a DSO just as soon as they see how little the CRO can do when compared to a modern DSO.  Assuming they hang around electronics long enough to find out...

I understand cash flow, I really do!  If the funds aren't there for a DSO, consider buying the least expensive CRO that can possibly do the job because it is certainly not going to be the last scope and there's no point in having a lot of money tied up in it.

[Mr. Scram]

Buying a CRO is simply deferring the cost of a DSO at the extra cost of the CRO.  The new user WILL be buying a DSO just as soon as they see how little the CRO can do when compared to a modern DSO.  Assuming they hang around electronics long enough to find out...

I understand cash flow, I really do!  If the funds aren't there for a DSO, consider buying the least expensive CRO that can possibly do the job because it is certainly not going to be the last scope and there's no point in having a lot of money tied up in it.

To be fair, a CRO could probably be sold at the same price. Then again, a DS1054Z doesn't tend to lose a lot of value either. Obviously, you need to be able to spend it in the first place.

[james_s]

Buying a CRO is simply deferring the cost of a DSO at the extra cost of the CRO.  The new user WILL be buying a DSO just as soon as they see how little the CRO can do when compared to a modern DSO.  Assuming they hang around electronics long enough to find out...

I understand cash flow, I really do!  If the funds aren't there for a DSO, consider buying the least expensive CRO that can possibly do the job because it is certainly not going to be the last scope and there's no point in having a lot of money tied up in it.

I used one for ~15 years of debugging microcontrollers and everything else before I ever had a DSO, they can do the job, some things are not as easy but there are workarounds. Sometimes deferring the cost is a necessity, I mean the mortgage on my house is really only deferring the cost, but financial realities made that a necessity. A CRO is better than no scope at all by a long shot, and if you don't have the budget for a DSO you don't have the budget.

It's strange to me how people seem to have forgotten already that it's only the last 10 years or so that any sort of DSO was within reach of all but the most serious hobbyists and yet somehow we got by and managed to create and debug all sorts of things, a DSO is a nice luxury, it's not a necessity. I wouldn't want to give mine up but I could get by without it if I had to.

[Mr. Scram]

I used one for ~15 years of debugging microcontrollers and everything else before I ever had a DSO, they can do the job, some things are not as easy but there are workarounds. Sometimes deferring the cost is a necessity, I mean the mortgage on my house is really only deferring the cost, but financial realities made that a necessity. A CRO is better than no scope at all by a long shot, and if you don't have the budget for a DSO you don't have the budget.

It's strange to me how people seem to have forgotten already that it's only the last 10 years or so that any sort of DSO was within reach of all but the most serious hobbyists and yet somehow we got by and managed to create and debug all sorts of things, a DSO is a nice luxury, it's not a necessity. I wouldn't want to give mine up but I could get by without it if I had to.

People did fine without cars, running water or electricity until very recently but I wouldn't want to be without them if I can help it. I could, but don't want to.

[james_s]

People did fine without cars, running water or electricity until very recently but I wouldn't want to be without them if I can help it. I could, but don't want to.

Plenty of people get by without cars, some for financial reasons, some because they just don't need one. Buses and bicycles aren't as convenient in many cases but they get the job done. Comparing running water to a DSO is a bit silly, if one is proficient an analog scope can do most of the things a DSO can do.'

Again, if you don't have the budget you don't have the budget. You get by with what you have or can afford.

[tggzzz]

People did fine without cars, running water or electricity until very recently but I wouldn't want to be without them if I can help it. I could, but don't want to.

Plenty of people get by without cars, some for financial reasons, some because they just don't need one. Buses and bicycles aren't as convenient in many cases but they get the job done. Comparing running water to a DSO is a bit silly, if one is proficient an analog scope can do most of the things a DSO can do.'

Again, if you don't have the budget you don't have the budget. You get by with what you have or can afford.

Precisely.

Doing more with less has another benefit: it gets you in the mindset that will enable you to do very advanced work. Simple example: what scope do you use when you are creating the world's fastest scope?

"An engineer is somebody that can do for $1 what any fool can do for $2" - Arthur M. Wellington

[Mr. Scram]

Doing more with less has another benefit: it gets you in the mindset that will enable you to do very advanced work. Simple example: what scope do you use when you are creating the world's fastest scope?

"An engineer is somebody that can do for $1 what any fool can do for $2" - Arthur M. Wellington

Yet you too have the fancy oscilloscope. What that means for being a fool I'll leave for the reader to decide.

[tggzzz]

Doing more with less has another benefit: it gets you in the mindset that will enable you to do very advanced work. Simple example: what scope do you use when you are creating the world's fastest scope?

"An engineer is somebody that can do for $1 what any fool can do for $2" - Arthur M. Wellington

Yet you too have the fancy oscilloscope. What that means for being a fool I'll leave for the reader to decide.

You're going to have to explain what you mean by that cryptic comment.

[wizard69]

Buying a CRO is simply deferring the cost of a DSO at the extra cost of the CRO. 

Exact!   The cost is deferred until the buyer has a better understanding of what he needs.   It is the difference between spending $50 or $500 to $5000.

The new user WILL be buying a DSO just as soon as they see how little the CRO can do when compared to a modern DSO.  Assuming they hang around electronics long enough to find out...

I don't really buy the idea that someone will rush out and buy DSO so quickly.   Especially if they have a functional analog scope.

As for the second point does it really make sense to invest huge bucks into what might be a hobby when you are getting started?    I mean seriously people here are rushing out to buy $300 desktop power supplies ot power up an Arduino that can run off a cheap plug pack.    I just don't see the wisdom in investing in high value stuff right out of the gate.

I understand cash flow, I really do!  If the funds aren't there for a DSO, consider buying the least expensive CRO that can possibly do the job because it is certainly not going to be the last scope and there's no point in having a lot of money tied up in it.

Yes that is the point for somebody starting out in this field as a hobby.   If this was an engineer setting up a "work at home" solution I can see a completely different set of answers being offered up.

One of the reasons I often suggest in these threads for newbies to build their own power supplies is the value in learning.   Even a kit offers plenty of soldering and assembly experience on usually forgiving bits and pieces.   It isn't just soldering of course, the more your power supply is DIY the more there is to learn.

 In the case of an O'scope a newbie can't realistically be expected to make one.   At the same time he doesn't have the background to use an advance DSO with an endless list of bells and whistles.  More importantly a newbie can't even specify his scope needs which is probably the best reason to put off a purchase.

[rstofer]

In the case of an O'scope a newbie can't realistically be expected to make one.   At the same time he doesn't have the background to use an advance DSO with an endless list of bells and whistles.  More importantly a newbie can't even specify his scope needs which is probably the best reason to put off a purchase.

Nobody knows where their hobby will head.  I've been fooling around with electronics since I was a kid - probably starting around '55 or so.  Even then, it hasn't been an active hobby all those years, I had other things to do and electronics would get shoved aside for years on end.  By the time I got my EE, I hated electronics!  Grad school revived it a bit.   You just never know what the future holds.

In the OP, nothing is mentioned about budget, why are we making assumptions?  What was asked is what scope was appropriate for Arduino projects.  The short answer is still:  just about anything rated 10 MHz or more.  To my knowledge, there are no pins on the ATmega328P Arduino that will toggle anywhere near 1 MHz.  The low dollar solution is an old low MHz analog scope.

Moving up to the Teensy 4.1 and its ability to toggle pins at 100 MHz is going to take a lot more scope.  It's debatable whether any of the entry level scopes are going to handle something like that.  The closest would be the Siglent SDS1104X-E unlocked to 200 MHz bandwidth and that's going to come up short.  But it may be good enough.

So, I can see where the hobby moves from ATmega328P to iMXRT1062 with no change in the underlying 'wiring' methodology.  Decades ago, a VP at the company I worked for and I were discussing large scale computer systems and the speed-power product.  He mentioned "Don't bet against technology!"  How right he was.  The same thing will happen with our hobby.  That 100 MHz entry level Rigol will be suboptimal for the next generation of chips.  But how much 'future proofing' can a hobbyist afford?

For the ATmega328P projects, a 10 MHz CRO will be entirely adequate.  Move one step up to the mbed LPC1768 and we're clocking at 60 MHz.

Since cost wasn't specifically mentioned, I don't see why it is being discussed.  Buying the Rigol and then reselling it down the line won't result in much of a loss.  Maybe $100?  Pretty cheap rent for a couple of years of use.

Not a poll:

• How many of the hobbyist respondents to this thread own a scope?  My guess:  all of them!
  
• Of those that own a scope, how many own a DSO?  My guess:  most of them.  There will be some CRO users that have had their CRO for a long time and see no reason to upgrade.  So be it!  It gets to the point of 'marginal utility'.  Are the DSO advantages sufficient to retire the CRO?  For some, yes, for others, no.  Or, in my case, I keep the high bandwidth Tek485 but I use the modern DS1054Z.
  
• Of those who use a scope for troubleshooting uC projects, how many want to step back and debug I2C without a scope?  My guess:  none of them!  Yes, a logic analyzer will do the job but it's pretty useless in the analog domain.  A scope does both...
  
• Of those who own a scope, if they didn't have one, would they be in the market for one in the near future?  My guess:  absolutely!
  

[radiolistener]

1) What problems do you solve with an oscilloscope?

electro debugging and AC or RF measurements

2) What bandwidth do I need?

minimum required bandwidth for hobby projects with 5-10 MHz signals is 100-200 MHz

3) Sample rate?

minimum sample rate for 100-200 MHz bandwidth is 1-2 GS

4) Memory depth?

look for at least 14 megapoints and above.
More memory depth, more detailed picture you can see and more slow time scale you can use with no aliases

[james_s]

Of those who use a scope for troubleshooting uC projects, how many want to step back and debug I2C without a scope?  My guess:  none of them!  Yes, a logic analyzer will do the job but it's pretty useless in the analog domain.  A scope does both...

I use a Bus Pirate to debug I2C and other similar interface, the scope can show me the signal so it's good as a quick check for signal integrity but I've never had a scope that can decode it so beyond verifying that the signal looks ok I don't really use my scope for that. For what it's worth, I did the same thing with an analog scope before I had a DSO, it allowed me to check the levels and verify that the clock rate looked reasonable but obviously it was not gonna decode anything.

[james_s]

1) What problems do you solve with an oscilloscope?

electro debugging and AC or RF measurements

2) What bandwidth do I need?

minimum required bandwidth for hobby projects with 5-10 MHz signals is 100-200 MHz

3) Sample rate?

minimum sample rate for 100-200 MHz bandwidth is 1-2 GS

4) Memory depth?

look for at least 14 megapoints and above.
More memory depth, more detailed picture you can see and more slow time scale you can use with no aliases

Funny, somehow I was able to work with signals >30MHz back when all I had was a 100Ms/sec 100MHz DSO, guess I must be a magician or something? Apparently I can do the impossible? Even now I never use anything even close to 14mpoints, my fingers would fall off scrolling through such a long capture.