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Kelly Herald wrote: Have you checked Mouser.com?
After your message, I have. Thanks!
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This is a question for the hardware hackers among us, particularly those with experience developing devices that use I2C, SPI, SDMMC, and/or I2S busses.
I write a lot software to communicate over such busses these days, and after abandoning the Arduino framework because it's too hobby-kit and not really great for commercial stuff, IMO - I've had to rewrite a lot of "driver" code because it exists for Arduino but not for example, for the ESP-IDF.
Debugging driver code bus issues are a pain - I really need to see the signals on the bus sometimes. This is why I want opinions from folks that have worked with an oscilloscope (or better tool?) to debug I/O on these busses.
What do you use? What do you recommend? Basically I need to (for example on I2C) wire up my scope to SDA and SCL lines, and see the timing on the SCL, to check the levels of the SDA to get my data 1s and 0s. Preferably I need a modern device that can log to my PC over USB, bluetooth or wifi because an I2c bus operates at 100khz and an SPI at 20, 40 or 80mhz a lot of times (at least on an ESP32) and I need to examine it after the fact to see the bits - or rather, the levels and edges I can translate to 1s and 0s.
If the scope can measure multiple inputs at once, and if it can sync to an external clock signal (for example, SCL on an I2C bus, or SCK? on an SPI bus) that would be awesome.
I don't care that much about cost, but I was hoping to keep it under $500USD unless there's compelling reason to spend more.
I also don't need a device that can handle a lot of current or voltage. I'm dealing with sub 12vdc, usually less than +5.5vdc, < 3amps
Real programmers use butterflies
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It's been years since I got my hands dirty on this stuff, but I hear good things about PicoScope gear[^] . The 2000 series would probably be enough for you, and it's certainly within your budget.
Cheers,
Peter
Software rusts. Simon Stephenson, ca 1994. So does this signature. me, 2012
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The PicoScope 2000 looks like just the ticket. Thanks!
Real programmers use butterflies
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Checked it out, it has built in support for I2C debugging, so that's really all you need it seems like.
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I was looking at it and I might spring for the 3000 since I don't think the 2000 can do SPI (not enough bandwidth)
The 3000 can do SPI 
It's got a price to match though. 
Real programmers use butterflies
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I haven't worked with oscilloscopes for many years, so I won't give any specific recommendations.
But, if you're measuring square waves you need at least ten times the bandwidth of what you're measuring.
Also if you're measuring a very low power circuit the probe itself puts a load in the circuit which changes the behaviour. If that's the case you might want to invest in an active probe.
This should not be a problem with I2C though.
<Edit>Might tell you though that my favourite used to be an Anritsu, but that recommendation doesn't have any bearing today.</edit>
modified 19-Mar-21 3:35am.
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Mine was always Tektronix - damn good scopes, and an excellent tech support department!
But again, irrelevant these days...
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
AntiTwitter: @DalekDave is now a follower!
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Worked with Tektronix, HP and Anritsu, and another one I can't remember now.
They were all good, but whoever designed the Anritsu was on the same frequency as me. Damn easy to work with.
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If it's for a hobby, then it might be worth looking at FleaBay for second hand stand alone scopes: A Tektronix TDS210 can be got for about the same price as a new PC-based USB scope, and will almost certainly come with better quality probes.
And I tend to worry about PC based scopes: just how good is the isolation, what's the chance of it putting spikes into the PC instead of absorbing them ... probably all groundless, but still.
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
AntiTwitter: @DalekDave is now a follower!
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It's at least in part, for commercial projects.
I need a PC based scope because decoding SPI and I2C signals by hand is a mug's game, never mind SDMMC.
I need the logic analyzer output to be able to be run through a software protocol decoder or I won't be productive.
I'm not concerned about isolation failure - my bench connects to my PC via a quality powered USB hub, so I've already got one level of isolation in place.
Real programmers use butterflies
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OriginalGriff wrote: And I tend to worry about PC based scopes: just how good is the isolation
Good catch, Picoscopes aren't isolated, so you need to know what you're doing.
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I've got isolation on my USB hub.  Nothing on my bench connects directly to my PC. Ever.
Real programmers use butterflies
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I hope you aren't confusing isolation with a fuse.
Just keep track of your ground and there should be no problem.
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The USB hub has a guarantee of protection for devices, which is part of why I bought it.
Now, those guarantees themselves? I'll probably never use one, but it tells me they've put some thought into power spikes.
Whether it's isolated or fused, it's enough for me.
My computer is worth only twice what one of these scopes will wind up costing me and everything I develop these days is under source control so if my house burns down because of a bad I2C +3.3vdc wiring job  I'll be fine.
Real programmers use butterflies
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I always view instruments that use part of a PC for operating are kinda dodgy, PICO scopes work for some but if you are dealing with I2C and tracing the signals can be a bit dodgy, as Windows is not real time OS it will do some thing else when you are trying to see if an out goes to ground and accurate time information...
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But the scopes I'm looking at have internal memory. I assume this basically has the effect of (if not being explicitly employed as) a buffer.
For example, the PicoScope 3000 has a 512 million sample buffer.
That's much more than I'm running for my ASIO audio output from my windows machine, and that demands "real time enough" performance from Windows as well - skips will skip the audio and people use this for live performances on stage all the time.
48khz@128bits per sample (2 channels, 64-bit floats/doubles for each channel, DAT quality) at 2ms buffer and no skips.
I need to do the math on this. meh.
Real programmers use butterflies
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Like I said, horses for courses! Tracing I2C you should be able to do with most PICO's but be aware that you are not 'seeing it' in real time. Also if you are running alot of stuff like ASIO audio, before running the scope unplug the audio and anything else that may put a demand on time... just sayin' been bitten by that...
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glennPattonContracting2 wrote: Tracing I2C you should be able to do with most PICO's but be aware that you are not 'seeing it' in real time.
Realtime actually wouldn't be that useful to me at all. It moves too fast. What I need is something that lets me *log* at the bus speed and then will display me the results after-the-fact. The key is though, I need to be able to reliably sample busses at 20MHz or maybe even 40MHz or I'll end up outgrowing this thing. 40MHz might be a bit of a stretch but if i can, bonus. The reason being is SPI works different on the ESP32 at different speeds, so I need to be able to check the bus in different speed configurations.
glennPattonContracting2 wrote: Also if you are running alot of stuff like ASIO audio
I'll put it on another core. I have 8 to pick from, each with two hardware threads. God bless Ryzen 7 APUs. I plan to do all this while I'm gaming too.
Seriously though, thanks for the heads up. I'll keep that in mind.
Real programmers use butterflies
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Sound like what you want is a Logic Analyser rather than a scope.
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TBH, I want both, and from what I've seen, modern offerings like that PicoScope line recommended upthread do both, but I probably should have asked for that to begin with. I still get the two mixed up even though I know the difference - am still relatively green with all the hardware mess.
Real programmers use butterflies
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I think I'm the opposite of "green" - last used a logic analyser in the 80s for a board I build running an 8088 processor (and the last time I did any x86 assembly!)
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This has been a trial by fire for me. I got into the hardware end of things w/ Arduinos and then ESP32 SoCs as a hobby but then I got scouted - on here actually - and now I'm doing it for keeps, and pretty soon I am getting into some real time industrial stuff for my next gig (same client, but he basically finds work for me - i tag along on his endeavors to provide hardware and software support and he finds the jobs but it's all b2b)
So the learning curve has been steep, but gratifying. I've not really messed with digital circuits (aside from basic repair) since I was six or seven when I had one of those 200-in-one kits from Radio Shack, until just recently. The toys are bigger and more complicated now.
Real programmers use butterflies
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I'm sure you'll have fun learning and get some great results!
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