Oscilloscope for Arduino/Raspberry Pi projects. 2 or 4 channel? Critical specs?

[nctnico]

scopes are not intended for grabbing and storing huge serial streams - get the right tool for the job if that's what you need to do.

An oscilloscope is the perfect tool for that job (analysing serial streams) because a lot of problems are in the analog domain which a logic analyser won't show at all. Unfortunately sometimes that means capturing lots of messages and sorting through them to find an intermittant problem.

[rx8pilot]

scopes are not intended for grabbing and storing huge serial streams - get the right tool for the job if that's what you need to do.

An oscilloscope is the perfect tool for that job (analysing serial streams) because a lot of problems are in the analog domain which a logic analyser won't show at all. Unfortunately sometimes that means capturing lots of messages and sorting through them to find an intermittant problem.

I use the scope for close looks at errors. They can be analog in nature or some other source of glitches. I use the Beagle to record and analyze long streams that allow me to see errors from logic in the programming of the system not physical layer errors. Those errors are hard to see up close as the scope see things and easier to see from a distance. At least with my designs anyway.

[lem_ix]

For example the two robots in the back of this video were made with an occasional use of a very crappy instek scope ( no decode, grading, etc, think it was a gds-1000) and cheap Chinese dmms.



Both have a raspberry pi connected to several sub boards which control actuators, sensors,motion, etc by modbus/rs485 and are autonomous, have collision detection and path finding. The ds1054z is capable of viewing pretty much anything in there, lacking maybe rs485 decoding? Don't worry too much about it and get a good C book, you'll spend most of your time on that.

[max100]

scopes are not intended for grabbing and storing huge serial streams - get the right tool for the job if that's what you need to do.
a $5 8channel 24MHz usb LA from china will sort that need.

That is the first step I will take thanks to the advice in this thread.

But what software do these use?  Investigating LAs this week I get the impression that Saleae has found a way to block the use of its s/w by other manufacturers' devices.  There is an open source project called sigrock.org ... Is that good?  All the Chinese LAs I have come across rely on 3rd party s/w.

[stj]

you can use Sigrok
http://sigrok.org/

or the saleae software, if you dont use the latest.
*or* replace the eeprom in the LA with a microchip brand 24LC00
(dont forget to copy the contents)'

[max100]

Thanks,
Is Sigrok good?
How do you get hold of the last open Saleae s/w?

[stj]

latest:
http://support.saleae.com/hc/en-us/articles/210245583-saleae-logic-beta-software

older:
http://support.saleae.com/hc/en-us/articles/210245603-Older-Saleae-Logic-Beta-Downloads

[Fungus]

All the Chinese LAs I have come across rely on 3rd party s/w.

Yep, that's why they're so cheap - no programmer's salaries to pay (or offices, or chairs...)

Is Sigrok good?

Not as good as saleae.

https://sigrok.org/wiki/PulseView

[max100]

Is Sigrok good?

Not as good as saleae.

https://sigrok.org/wiki/PulseView
[/quote]

Functionally not as good? If so in what way?
 I can live without a fancy user interface.

[Fungus]

Functionally not as good? If so in what way?
 I can live without a fancy user interface.

You're the only person who knows what you want. See the websites for manuals, documentation, etc.

At a screenshot level it's this:



vs. this:

[Fungus]

To be honest: I dislike small oscilloscopes, probably due to a horror experience in past militia service. if I can pick up a scope and throw it easily, it is not for me.

You once threw a scope and it wasn't heavy enough? Now you have nightmares?

Details, man, details... 

[max100]

Functionally not as good? If so in what way?
 I can live without a fancy user interface.

You're the only person who knows what you want. See the websites for manuals, documentation, etc.

At a screenshot level it's this:

....

vs. this:

....

Have you used them or is your opinion based on the user interface screenshots?

[Fungus]

Have you used them or is your opinion based on the user interface screenshots?

Saleae is nicer, more complete.

Sigrock does the job.


More info here: https://encrypted.google.com/search?q=sigrock#q=sigrok&tbm=vid

[TAMHAN]

To be honest: I dislike small oscilloscopes, probably due to a horror experience in past militia service. if I can pick up a scope and throw it easily, it is not for me.

You once threw a scope and it wasn't heavy enough? Now you have nightmares?

Details, man, details... 

Let us just say: higher-ranking girly with extra sexy feet (sexy-meter:      even in highest setting) and a very beepy and crashy scope from an unnamed manufacturer. And no, I didnt throw it. Just hated it.

But back to the main topic: one more very important feature, IMHO, is Peak Detect. I linked my video in the page before...and tonight just thought that this kind of problem is likely to also happen in robotics.

P.S. That PulseView screenshot looks better than Salae TBPH, at least for me. I dislike Salaes "farty-party" user interface.

[Fungus]

P.S. That PulseView screenshot looks better than Salae TBPH, at least for me. I dislike Salaes "farty-party" user interface.

Me too.

[TAMHAN]

Sadly, my Chinese clone is said to show preference to Salae ;(

[madires]

P.S. That PulseView screenshot looks better than Salae TBPH, at least for me. I dislike Salaes "farty-party" user interface.

I fully agree. Salae's UI looks too cool to be useable, more like a fancy gadget for kids or a hacker movie. PulseView on the other hand focuses on the data, which I'd consider a tool. When I have to look hard to see the data, the UI is done wrong.

[Fungus]

I fully agree. Salae's UI looks too cool to be useable, more like a fancy gadget for kids or a hacker movie. PulseView on the other hand focuses on the data, which I'd consider a tool. When I have to look hard to see the data, the UI is done wrong.

Pale grey on slightly darker grey is fashionable. You see it in every modern UI.

PulseView looks like it was written before 2010.   

[rf-loop]

I fully agree. Salae's UI looks too cool to be useable, more like a fancy gadget for kids or a hacker movie. PulseView on the other hand focuses on the data, which I'd consider a tool. When I have to look hard to see the data, the UI is done wrong.

Pale grey on slightly darker grey is fashionable. You see it in every modern UI.

PulseView looks like it was written before 2010.   

Modern is not synonym for better or good. 

[tggzzz]

I fully agree. Salae's UI looks too cool to be useable, more like a fancy gadget for kids or a hacker movie. PulseView on the other hand focuses on the data, which I'd consider a tool. When I have to look hard to see the data, the UI is done wrong.

Pale grey on slightly darker grey is fashionable. You see it in every modern UI.

PulseView looks like it was written before 2010.   

Modern is not synonym for better or good.

Very true.

While I don't like skeuomorphic GUIs, the modern "flat" design has gone to the opposite extreme. It has regressed to the middle-80s style where it can be difficult to determine whether a widget (e.g. tab) is activated, or even whether something is a pressable widget! I remember when Motif introduced the "3D" effect, and how much easier it made using GUIs.

One simple example: my ISP has a web page with two tabs, one black and one white. Guess which tab is already visible, and which can be pressed to show the other information. With even a minimal 3D cue, it is obvious.

[rstofer]

P.S. That PulseView screenshot looks better than Salae TBPH, at least for me. I dislike Salaes "farty-party" user interface.

Me too.

I went looking at the Salae Pro 16 (it is recommended around here from time to time) and I have already installed Sigrok for one of the uber cheap LAs.  The Salae doesn't seem to support state analysis and, for me, that is fatal.  I'm pretty sure the cheap LA I have hooked to Sigrok doesn't support it either and I have no idea whether the software itself supports it.

State analysis, to me, is the most important capability.  I may not use it every single time but many times I want to know the state of signals at the actual clock edge, not some sampled clock.

The Salae software, AFAICT, doesn't have much of a triggering system.  First of all, I want 32 channels.  Ignoring that, I want a staged trigger such that I can form 4 stages (layers) of trigger logic states.  See this pattern, followed by that pattern, followed by another pattern, followed, finally, by the last pattern: trigger now!  I should be able to include or exclude all bits, invert all bits and form AND equations.  I don't see it in the  Salae documentation and I don't think I'll find it in the Sigrok stuff either.

Some of these logic analyzers aren't analyzers at all.  They are just binary scopes sampled at some low rate with no timing relationship to the device under test.

All that said, the Salae software is pretty polished.  That's easy when they aren't trying to interface to hundreds of different devices.  Sigrok has quite a list of compatible pieces of gear.

[stj]

if you want a real clock, and not just a 33rd channel, you probably need to look at something like a sump.

http://www.sump.org/projects/analyzer/

[rstofer]

if you want a real clock, and not just a 33rd channel, you probably need to look at something like a sump.

http://www.sump.org/projects/analyzer/

Actually, I have the Sump logic analyzer.  If you search the site, you will probably see where I contributed a level shifter design.

There are a couple of things I don't care for:  First, I don't have it 'packaged' so it lays around my bench like another project.  Second, i'm not stoked about Java and, more particularly, having to find the 'look and feel' library and the RXTX library.  About 3 Java updates back, the GUI quick working and I have never gotten it working again.  My fault, I just haven't spent the time it takes to get it working.  I'm sure somebody has already figured it out.

That LA is a really sweet unit for the cost.  The original design for the Spartan 3 Starter Board was a blessing when I was working on my 1130 project because it also used the Starter Board.  I'm not sure what boards are currently supported but it does talk about the issue on the site.  The Starter Board is no longer available.

[Rick Law]

Hi,  I am an inexperienced hobbyist in need of help selecting an oscilloscope for Arduino/Raspberry Pi robotics projects.
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Will really appreciate benefit of experienced/expert opinions.

Many thanks.

I can only speak for this hobbyist - I just want the most economical solution and don't want to make the mistake of buying an inadequate instrument that I subsequently need to replace because of inadequate research.
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I am a fellow hobbyist, so my opinion is definitely NOT an expert's opinion.  But having the "engine starting" not so long ago, I remember how it was like.  The discussions about which scope is useful/good are no doubt very valuable.  But I suggest perhaps you should see what problems stand in your way first.

If I am to say: to really do electronics right, you should learn calculus first - you (or I should say, most) would not get started in electronics.  No doubt calculus is both important and enlightening in solving many electronic problems.  But you don't need that just to play with Arduinos/Raspberry.

At the get-go, I saw all those candies and I want them.  I ran in circles at the starting-gate.   I eventually just got moving with a low cost DMM, then later added a low cost Scope.  At the get-go, I wanted to have a 100,000 count DMM, but it turns out I don't need it.  I wanted to have a 100mhz 1meg datapoint scope.  Turns out in my case I rarely use a scope...  I still want a 100,000 count+ DMM, but I don't need it to get started.  I still like a 400Mhz scope, but I don't need it to get started..

Don't worry too much about having to replace your equipment.  By the time you learn enough to need a better DMM or a better Scope, there will be far better choices (performance) products then.  You also would be much better equipped to find one much more suitable for your need.  Besides, there is a good chance you may make newbie mistakes that even the very best equipment may not survive.  So top shelf stuff may not be best for a new-newbie.

The trouble with a Lamborghini is, you really don't want to learn how to drive with it.

When you get to the point of doing the upgrade, the old/cheap stuff that you used to learn with will always have a home.  A second scope or a second DMM (low cost starter) will always have a use.

Again, just a fellow novice merely a steps or two ahead of you - trying to share what I know.

Rick

[Wuerstchenhund]

If I am to say: to really do electronics right, you should learn calculus first - you (or I should say, most) would not get started in electronics.  No doubt calculus is both important and enlightening in solving many electronic problems.

+1    And not just calculus, also a general understanding of the basic physics and math behind it (i.e. that all waveforms are made up of multiple sine waves at various frequencies).