The eternal question: which scope should I buy?

[Fungus]

I'd second the suggestion of getting a logic analyser now and a scope a little bit later.

NO NO NO NO! I've seen people struggle for weeks trying to find a problem with a logic analyser and fail. An oscilloscope shows the problem immediately. After a DMM an oscilloscope is the next piece of test equipment you need.

A logic analyzer is for when the comms are working and you want to look at the packets of data to find protocol bugs.

The scope is for when the comms is failing and you don't know why.

[Gandalf_Sr]

I don't disagree with you on the strengths and weaknesses of each, I'm just considering the OP's situation. The key things are "on a budget", "just starting out" and "Arduino". He's more likely to be inspecting serial comms on a prebuilt board. Far more working out the basics of what's going on that any subtle signal quality issues. A scope is indeed a better tool, but is the expense worth it right now?

I'm sure the OP can consider both sides and decide for himself what his priorities are. I'm guessing that if he's asking about scopes then the gadget lust has probably taken hold anyway!

I have comments on the protocol analyzer on the scope vs a dedicated logic analyzer.  Obviously the scope can see the waveforms but the sub-$1,000 scopes are all software decoders which makes them fairly slow.  You can get scopes with hardware decoding built in such as the (now obsolete) Agilent MSO7104B but they are expensive - I own a Rigol MSO2072A with software decoding and it's sloooowwww to the point of being unusable.  There's a poorly documented but powerful and cheap Bus Pirate that can show actual traffic on I2C and SPI busses which I highly recommend or you can spend maybe $150 for a reasonable logic analyzer.
In short, scopes are good to look at waveforms, analyzers are good to read the actual traffic contents.

[Fungus]

There's a poorly documented but powerful and cheap Bus Pirate that can show actual traffic on I2C and SPI busses which I highly recommend or you can spend maybe $150 for a reasonable logic analyzer.
In short, scopes are good to look at waveforms, analyzers are good to read the actual traffic contents.

Bus Pirate is expensive. Most people use the $6 devices from eBay with a copy of sigrok.

nb. I'm not saying Bus Pirate is worthless, it can do a lot more things than a logic analyzer. If all you want is a logic analyzer though, get the $6 gadget.

[Gandalf_Sr]

Thanks Fungus, I just ordered from eBay, one of those $6 units from China, I was unaware that Sigrok existed until now.  Is there a thread on this device anywhere on eevblog?

[Fungus]

Thanks Fungus, I just ordered from eBay, one of those $6 units from China, I was unaware that Sigrok existed until now.  Is there a thread on this device anywhere on eevblog?

They've been mentioned a couple of times.

There's not really much to know. It's a small black box (literally and figuratively) that connects between your digital logic device and your PC software (eg. Sigrok). Bandwidth is enough for Arduino work.

[CharlieWorton]

Well, the die is cast!

I had a chat with Electro-meters, who are the Canadian distributors for Rigol.  They offered me a 5% educational discount, free shipping, and a 3 year warranty.  With tax, it's coming in at $525.00 as opposed to Amazon, who were coming in at $583.00.  So, a total savings of $58.  Not bad!

So, I've purchased the Rigol.  They're going to ship today, and I should have it early next week.  I expect the 3 year warranty will vaporize when I upgrade the machine to 100Mhz, but that was always going to be the case no matter where I bought it from.

By the way, they didn't ask for my student ID # or any other supporting documentation.  They simply accepted my word.  That was refreshing.

So now, I'm all excited.  I'm a Rigol fan boy club member now.  Gotta get way deep into the literature and the mystique.

Anybody know if I will need to apply a system update?  Or are they shipping them with the latest version?

Oooooh, so excited.  Hope this works!

Later, all - Charlie

[Fungus]

I expect the 3 year warranty will vaporize when I upgrade the machine to 100Mhz, but that was always going to be the case no matter where I bought it from.

No worries. You can easily remove the upgrade, nobody will know.

[TK]

I don't disagree with you on the strengths and weaknesses of each, I'm just considering the OP's situation. The key things are "on a budget", "just starting out" and "Arduino". He's more likely to be inspecting serial comms on a prebuilt board. Far more working out the basics of what's going on that any subtle signal quality issues. A scope is indeed a better tool, but is the expense worth it right now?

I'm sure the OP can consider both sides and decide for himself what his priorities are. I'm guessing that if he's asking about scopes then the gadget lust has probably taken hold anyway!

I have comments on the protocol analyzer on the scope vs a dedicated logic analyzer.  Obviously the scope can see the waveforms but the sub-$1,000 scopes are all software decoders which makes them fairly slow.  You can get scopes with hardware decoding built in such as the (now obsolete) Agilent MSO7104B but they are expensive - I own a Rigol MSO2072A with software decoding and it's sloooowwww to the point of being unusable.  There's a poorly documented but powerful and cheap Bus Pirate that can show actual traffic on I2C and SPI busses which I highly recommend or you can spend maybe $150 for a reasonable logic analyzer.
In short, scopes are good to look at waveforms, analyzers are good to read the actual traffic contents.

I am certain the Keysight 1000X scope has hardware decoders implemented on the ASIC IV

[TK]

I expect the 3 year warranty will vaporize when I upgrade the machine to 100Mhz, but that was always going to be the case no matter where I bought it from.

AFAIK the Rigol hack can be uninstalled issuing SCPI commands, so warranty will be intact.  Just uninstall the hack before shipping back to Rigol

[schmitt trigger]

Well, the die is cast!

I had a chat with Electro-meters, who are the Canadian distributors for Rigol.  They offered me a 5% educational discount, free shipping, and a 3 year warranty.  With tax, it's coming in at $525.00 as opposed to Amazon, who were coming in at $583.00.  So, a total savings of $58.  Not bad!

So, I've purchased the Rigol.  They're going to ship today, and I should have it early next week.  I expect the 3 year warranty will vaporize when I upgrade the machine to 100Mhz, but that was always going to be the case no matter where I bought it from.

So now, I'm all excited.  I'm a Rigol fan boy club member now.  Gotta get way deep into the literature and the mystique.

Oooooh, so excited.  Hope this works!

  Congrats!
You'll love it.

The good thing about a scope, is that it has variable vertical ranges. You'll be able to see from about 2mV/div to 200V/div (with the proper probe settings). In other words, you may troubleshoot power supplies, sound cards, sensors and that kind of stuff.

[pascal_sweden]

I am certain the Keysight 1000X scope has hardware decoders implemented on the ASIC IV

What about the new Siglent SDS1202X-E? Isn't the decoding there also done in hardware?

Note that there is a major probe compensation drift issue on the Keysight 1000X scope.
This issue has been reported more than 5 weeks ago, and Keysight still has no resolution or mitigation plan in place. In fact I believe they even have dropped the investigation completely.

[TK]

I am certain the Keysight 1000X scope has hardware decoders implemented on the ASIC IV

What about the new Siglent SDS1202X-E? Isn't the decoding there also done in hardware?

Note that there is a major probe compensation drift issue on the Keysight 1000X scope.
This issue has been reported more than 5 weeks ago, and Keysight still has no resolution or mitigation plan in place. In fact I believe they even have dropped the investigation completely.

I think SDS1202X-E decode is done by software on the Zynq CPU.

Can you post a proof of the MAJOR probe compensation drift issue?  Have you experienced it yourself?  I have the EDU 1000X scope and it is not an issue for me.