Author Topic: Smartscope  (Read 21755 times)

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Offline rthorntn

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Smartscope
« on: January 22, 2014, 08:43:51 pm »
http://www.kickstarter.com/projects/751733865/smartscope-reinventing-the-oscilloscope/description

2x100MS/s 50MHz Oscilloscope
50MS/s Arbitrary Waveform Generator
Digital logic analyzer at 100MS/s
Digital waveform generator at 100MS/s
200 waveforms/second data updates
 

Offline Maxlor

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Re: Smartscope
« Reply #1 on: January 22, 2014, 09:12:45 pm »
I really like the Android OTG part. A scope running off batteries is useful sometimes, and a Nexus 7 would be a pretty awesome display.

But why does it only offer 2048 samples, even in logic analyzer mode? If it did streamed sampling in LA mode, I'd probably buy it just for that. (Saleae, take the hint and build an Android version of your software!) As it is, it seems too limited to be useful to me. But hey, maybe the next version will have more storage? I'll keep an eye open for that.
 

Offline Fsck

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Re: Smartscope
« Reply #2 on: January 23, 2014, 02:06:11 am »
Well, if this is the <<guys, all I can say for now: be prepared for another kickstarter launch in 10 days from now, which will solve your questions in a more professional approach, offers more and... comes even at a lower cost (especially for the 100 early birds)>> post from the DSLogic thread: then I'm depressingly underwhelmed: the hardware still makes me think toy rather than test equipment.

tablet functionality would probably be neat for portability.
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Online BravoV

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Re: Smartscope
« Reply #3 on: January 23, 2014, 02:13:17 am »
Wonder if the USB interface is isolated ? Can't find it in the KS page.

Offline Harvs

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Re: Smartscope
« Reply #4 on: January 23, 2014, 04:55:25 am »
All the significant hardware limitations aside, I don't like the sound of the cross platform software.  Maybe it's fine...  But I would have thought a fair bit of work would need to get decent update rates on a mobile device without bogging the UI.

But then again, with only 2k samples it probably doesn't take much processing power to render.
 

Offline senso

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Re: Smartscope
« Reply #5 on: January 23, 2014, 07:20:57 am »
So 2048 samples are enough to fill a full HD screen and 200 waveforms per second are 200fps which is way faster than the competition, and for only 200€, oh boy
 

Offline pickle9000

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Re: Smartscope
« Reply #6 on: January 23, 2014, 08:02:10 am »
So 2048 samples are enough to fill a full HD screen and 200 waveforms per second are 200fps which is way faster than the competition, and for only 200€, oh boy

Put that way it sounds like a digital version of an analogue scope.
 

Offline Harvs

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Re: Smartscope
« Reply #7 on: January 23, 2014, 08:47:43 am »
200 waveforms per second are 200fps which is way faster than the competition,

Forgive me for being a touch dubious about this one.  But getting an Android device to render at 200fps isn't actually that easy even on a modern device, that's only 5ms per frame.  Sure transfer the data to the device at that speed no worries, but they've actually said 200 frames per second in the spec.  Do mobile devices even have a screen refresh rate that high?
 

Offline eev_makr

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Re: Smartscope
« Reply #8 on: January 23, 2014, 09:53:27 am »
Great that our project is being picked up at the eev forum!

Yes indeed – the comment posted earlier was coming from me. At that time I KNEW I shouldn’t post it, but it’s hard to imagine the feeling of being so close to the launch of a Kickstarter – definitely recommended to anyone! The next morning I couldn’t believe I actually posted that message – but hey now it’s there and now much I can do about it now :)

Since I don’t want to draw any activity from this forum to the KS comments section, let me answer your doubts here.

  • It does run off the batter of your tablet/phone, but you can also hot-plug external power through the separate microUSB, in case your tablet battery runs low
  • The reason we’re only storing 2k samples is because we decided to have a clear focus, and to focus on making an oscilloscope affordable to anyone. For a scope, we wanted to make sure that all pixels of a fullHD screen are covered – the only case where you want to have more samples, if when you take a single shot and zoom in. Which is definitely not a rare use-case, but adding a DRAM element + controller would have added at least $30 is selling price (taking cost,taxes, storage, time for testing at production and logistics into account). It was one of the hardest design choices we had to make – but in the end we think we made the right choice. And hey – you need to leave us some headroom to put some stretch goals ;)
  • For the logic analyzer, 2k samples will allow you to debug most digital interfaces. And because we know that the amount is on the low side for pure logic analyzer purposes, we’re thinking about implementing encoding schemes, so you can store 2k transitions, instead of 2k samples.
  • Honestly I’m a bit disappointed you think it looks like a toy – but hey optical perception is something one cannot argue about. We spent addition $ to offer you a full metal case – which is also required to shield the analog part from incoming noise. We have bidirectional high-speed low-capacitance protection diodes on all pins. We manage our USB inrush current to stay within USB certification limits. If you have any additions you would like to see that we can still slip in, let us know.
  • USB is not fully isolated – another tradeoff we had to make. However: the 5V is diode-protected, so we make sure there is no voltage injected into the host – ever. Which in our view should protect the SmartScope in most cases things could wrong.
  • 200eur? It’s $179 ;)
  • Regarding the FPS: it is important to make the distinction between 2 refresh rates. First, there’s the ‘waveform refresh rate’ or ‘USB refresh rate’, which is the rate at which waveforms are captured and sent to the host. Let’s talk ‘ups’: updates per second. For this, we reach 200ups on PC, about 80fps on iOS devices and 170ups on Android devices. Then, there is the screen refresh rate, which is the 1/interval at which the waveforms are displayed on the screen. We’re clipping this to 50fps on PC, and reach anywhere between 10fps till 50fps on iOS and Android devices, based on their CPU and GPU specs. Now you probably think: are there benefits to have a ups which is larger than the fps? Yes. Amazing ones. It allows us to blend eg the last 10 waveforms on top of each other, which is giving you a much smoother waveform visualization than you would otherwise get, and it gives an opportunity to show all captured waveforms. So yes, even with 10fps you will see each of your 200ups.
I hope this gives some more background to the thoughts you mentioned. We would love to make our kickstarter page 10x as long as it is now, but KS adviced to keep it this size. Perhaps, we should wrap all this information in a early shape of manual, for those of you requiring a more advanced explanation. Anyway, we’ll try to check here every now and then to see if there are more questions.
 

Offline Maxlor

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Re: Smartscope
« Reply #9 on: January 23, 2014, 10:29:25 am »
  • The reason we’re only storing 2k samples is because we decided to have a clear focus, and to focus on making an oscilloscope affordable to anyone. For a scope, we wanted to make sure that all pixels of a fullHD screen are covered – the only case where you want to have more samples, if when you take a single shot and zoom in. Which is definitely not a rare use-case, but adding a DRAM element + controller would have added at least $30 is selling price (taking cost,taxes, storage, time for testing at production and logistics into account). It was one of the hardest design choices we had to make – but in the end we think we made the right choice. And hey – you need to leave us some headroom to put some stretch goals ;)
  • For the logic analyzer, 2k samples will allow you to debug most digital interfaces. And because we know that the amount is on the low side for pure logic analyzer purposes, we’re thinking about implementing encoding schemes, so you can store 2k transitions, instead of 2k samples.

Well, please notify us if the deluxe version with DRAM comes along. If it's really only $30 more (or even $50), and your software can handle the increased amount of data smoothly, that sounds like a toy  ;) I'd like to own.
 

Offline Harvs

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Re: Smartscope
« Reply #10 on: January 23, 2014, 10:40:11 am »
  • Regarding the FPS: it is important to make the distinction between 2 refresh rates. First, there’s the ‘waveform refresh rate’ or ‘USB refresh rate’, which is the rate at which waveforms are captured and sent to the host. Let’s talk ‘ups’: updates per second. For this, we reach 200ups on PC, about 80fps on iOS devices and 170ups on Android devices. Then, there is the screen refresh rate, which is the 1/interval at which the waveforms are displayed on the screen. We’re clipping this to 50fps on PC, and reach anywhere between 10fps till 50fps on iOS and Android devices, based on their CPU and GPU specs. Now you probably think: are there benefits to have a ups which is larger than the fps? Yes. Amazing ones. It allows us to blend eg the last 10 waveforms on top of each other, which is giving you a much smoother waveform visualization than you would otherwise get, and it gives an opportunity to show all captured waveforms. So yes, even with 10fps you will see each of your 200ups.

What you've described there is what pretty much everyone understands as waveforms per second on a standard DSO datasheet, which very few will argue are useless.  Infact that's a very important selling point of most modern scopes.  So can I suggest changing the nomenclature of your kickstarter page to use the standard terms, and remove the reference to claiming 200 frames per second.
 

Offline EEVblog

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Re: Smartscope
« Reply #11 on: January 23, 2014, 11:09:44 am »
You need way more than 100MSamples/sec for 50MHz BW scope! .. way to few sample points to see any meaning full waveform detail.

With SinX/x interpolation you need about 4 times the bandwidth in sample rate, if not, 10 times is the typical figure.
 

Offline Polossatik

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Re: Smartscope
« Reply #12 on: January 23, 2014, 02:45:12 pm »
  • 200eur? It’s $179 ;)
  • Regarding the FPS: it is important to make the distinction between 2 refresh rates..
while 189 usd is only 140€ , please realize that EU backers need to pay customs on US shipments, which is easily an extra 60 € ... this not your fault obviously but at then end it means an 179 usd device will cost me about 200€ when coming from the USA.

And for an device aimed at technical people i do find using meaningless statements like "2048 samples / enough to fill a full HD screen " a bit silly.

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Offline leppie

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Re: Smartscope
« Reply #13 on: January 23, 2014, 03:06:30 pm »
I wish they would add some arbitrarily settable function knobs on these USB scopes. 
 

Offline Bored@Work

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Re: Smartscope
« Reply #14 on: January 23, 2014, 05:48:08 pm »
I wish they would add some arbitrarily settable function knobs on these USB scopes.

But in their video they condemned scopes with knobs.  |O Bunch of young whippersnappers ...
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Offline Fsck

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Re: Smartscope
« Reply #15 on: January 23, 2014, 06:01:32 pm »
I'd like to point out it's not the design that makes me think toy, it's the hardware. I don't really care about physical design unless it is somehow detrimental to functionality.

big ass buffer is ideal, and everyone really wants their 4-channel oscilloscope for cheap(er). 16 channel LA would be nice as well if you could maintain 100M sampling. (high hopes), but that would probably be the ultimate in portability if you could do at least 1GSa over 4 channels oscope.

I don't really know of a cheap way to the above, but that's why I place my hopes on the startups.
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Offline eev_makr

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Re: Smartscope
« Reply #16 on: January 25, 2014, 12:02:36 am »
@Maxlor: so please let me know exactly what usecase you have in mind. Most guys in this forum probably have 10 different scopes at home, so the ideal crowd to validate and fine-tune our stretch goals (hey the SmartScope would make a great 11th!)

@Harvs: thanks, changed that in the text. (I spent the past 9 years designing USB cameras, which should explain my dialect)

@Dawgie: I had the same comment on the KS site. I (arguably) changed the advertized bandwidth from 50MHz to 45MHz, as this really is our 3dB point and not simply the Nyquist freq of 100MS/s. So I agree with David that you shouldn't expect great results when looking at signals with significant spectral contents above 20MHz, but at least what you see will be close to reality.

@Polossatik: nice coincidence, if you're close to Brussels or Antwerp you can always pass by to pick yours up ;)

@Bored\@Work: English is not my native language -- but isn't whippersnapper the opposite of old fart? ;) Thanks for checking out the video!

@Fsck: hey you need to leave us some room for a next product!
 

Offline Bored@Work

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Re: Smartscope
« Reply #17 on: January 25, 2014, 09:24:14 am »
@Bored\@Work: English is not my native language -- but isn't whippersnapper the opposite of old fart? ;) Thanks for checking out the video!

Yes, something like this. And it is a bit obvious you cater more for the young hippster type with more money than brains. Thing is, they are flaky. Someone else showing them some other new shiny toy and they are gone.
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Offline Bassman59

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Re: Smartscope
« Reply #18 on: January 26, 2014, 04:26:25 am »
I really like the Android OTG part. A scope running off batteries is useful sometimes, and a Nexus 7 would be a pretty awesome display.

But why does it only offer 2048 samples, even in logic analyzer mode?

It's obviously limited by the amount of BRAM in the Spartan 3A FPGA.

-a
 

Offline Maxlor

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Re: Smartscope
« Reply #19 on: January 26, 2014, 02:06:45 pm »
@Maxlor: so please let me know exactly what usecase you have in mind. Most guys in this forum probably have 10 different scopes at home, so the ideal crowd to validate and fine-tune our stretch goals (hey the SmartScope would make a great 11th!)
I come to electronics from the digital side of things. I work with events much more often than continuous signals, that means I capture something, then analyze it. Having a scope with a bit of memory allows me to not have the settings perfect the first time but instead pan and zoom a bit. So that offers me more comfort and flexibility, and makes me think less hard about what exactly it is that I need.

I'll give you a concrete example: last week I was working on my wireless sensor node. It runs off a coin cell, and the wireless module does draw a bit more power than what's wise for a coin cell, but it just about works. Because of the large inner resistance of a coin cell, you see very clearly however when the module wakes up and goes to sleep, and when it starts and stops sending, because the battery voltage changes slightly. The goal is then to make the module go back to sleep as quickly as possible.

I'm using SPI to talk to the module. First I send it the data it should transmit, then I poll whether it's done, then I tell it to go back into standby. The whole affair took about 10ms, so I had my scope capture that. Upon noticing the actual wireless transmission takes less than 1ms, I wondered what the module's doing for the other 9ms, so I started looking at the communication a bit more closely to understand how the SPI communication correlates to the module's activities. I learned then for example that there's no point in starting to poll for end-of-transmission immediately, I can let my MCU sleep for 1ms. With a couple of other modifications, I got the module active time down to 4ms.

So what I'm saying here is, it was really helpful to be able to capture 10ms, then be able to zoom into it enough to decipher the 2MHz SPI communication. That'd require about 40kpts per channel. Granted, it could have been done with at least enough resolution to see that SPI communication is going on, and how many bytes are transmitted (2kpts maybe?), the counting and comparing with what the micro sends out, but the task then becomes more difficult and error-prone. Working with a shorter time base to see just parts of the full signal, and thus be able to see the SPI communication more clearly is not that helpful in this case, because you only have a couple of external reference points (module turns on/off, starts/stops sending.) If they are outside of the displayed area, it's much harder to understand whats going on. And again, harder -> more mistakes.

As for the LA part: storing only transitions instead of constant sampling, those 40kpts would come down to... maybe around 1600 transitions on the clock line (100 bytes transmitted)? And I don't think that's a particularly long sequence. With an NFC card reader we were integrating into a project some time ago, you'd have both lengthy setup sequences (with long pauses mandated by the NFC chip) and long data transmission sequences (1KB NFC cards are not uncommon, and the resulting on-wire communication sequence has overhead.) Now, most of that data is probably not interesting, but if you're interested in the end of the sequence (what's the last thing the NFC chip sends before hanging?) you either need some clever triggers or just have a comfortable amount of memory to work with.

I hope that helps illustrate my point of view a bit. I'll be watching those stretch goals  ;)  Or maybe the second version. It might be better to ship what you have now, and build a more complex model later, with all the added experience you get from the first run.
 

Offline eev_makr

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Re: Smartscope
« Reply #20 on: January 29, 2014, 08:03:06 pm »
Thanks for giving such an elaborate description. Basically, you mean you want more memory :)

I have to admit that almost all suggestions for improvements we get, are coming down to adding more sample depth. Although I'm considering the current version of the smartscope (close to reaching 100% funding now!!!), we are looking in possibilities to add RAM as a stretch goal. It's not going to be easy. The cost hit to us will be huge: larger FPGA, more FPGA pins, RAM block, 4 layers -> 6 layers, top-and-bottom SMT, additional power rail.... while we cannot ask more money. The worst thing to do would be to provide 2 different products. We're discussing with component suppliers on a daily basis, but it's going to be very though., I can't make any promises right now. I can assure you, we already did an extreme effort to propose the original functionality at $179. Will take a couple more sleepless nights :)
 

Offline hans

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Re: Smartscope
« Reply #21 on: January 29, 2014, 08:50:49 pm »
I may also want to comment on the choice of the PIC microcontroller.

I suspect this device will handle the USB connection to the tablet or PC. Honestly, I don't get why you would put such a part there, it creates a huge bottleneck. There are plenty of USB2.0 microcontrollers (Cypress has some, probably some of the newer big ARM chips as well) or chips around (like the FTDI FT232HL) that boast USB Hi-Speed (480MBit/s) .

Practically every respectable quality USB o-scope has such a device in place for increasing the max streaming speed. I suspect the current 200wfm/s is limited to the transfer speed of this PIC: 2x2048x200 = 819.2ksps streaming, or 6.5Mbit/s  (which sounds about right for a 12Mbit/s USB connection).

If you would increase the maximum sample buffer, you really would need to increase the connection bandwidth as well. Otherwise you're stuck with a 512kB sample buffer and <2fps...

In the end the purpose of digital parts of an o-scope is to process and display as much data from the ADC's as possible. In this case the ADC's produce 100MB/s (100MSPS @ 8-bit) of data each, so even that wouldn't fit through USB2.0. However, getting as close as possible would contribute much to the usability. If you look at a scope like TiepieScope Handyscope HS5, although in a complete different price range: it boasts 20MSPS streaming @ 14-bit (so about 40MB/s).
I believe they are looking into adding USB3.0, as probably many other USB scope manufacturers are.

I don't know what much else the PIC is doing what couldn't be done in the FPGA, but I would kick the PIC out and place a FT232HL in there. But as said, it's hard to incorporate now, as the FTDI chip probably costs extra, redesign costs extra, etc., for 0 extra income (unless you make a Pro/deluxe version)
« Last Edit: January 29, 2014, 08:52:36 pm by hans »
 

Offline Maxlor

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Re: Smartscope
« Reply #22 on: February 07, 2014, 10:29:24 pm »
So the SmartScope guys have now added 16Mbit of RAM as an option. Time to put my money where my mouth is, count me in :)

Now I'm just hoping that the software will be able to make good use of the added features. I guess we'll see!
 

Offline scientist

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Re: Smartscope
« Reply #23 on: February 08, 2014, 08:36:52 pm »
I wish they would add some arbitrarily settable function knobs on these USB scopes.

This.
 

Offline Rasz

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Re: Smartscope
« Reply #24 on: February 09, 2014, 06:43:57 am »
1 "At $179 we believe there's no one out there offering a comparable scope"

you believe wrong
Your hardware is somewhere between Hantek 6022BE and Hantek DSO2090, still worse than the second while being more expensive to start. Not to mention cheapest Picoscope is 10x better while still being cheaper.
The only distinctive feature you offer is tablet app, but there is maybe 2 seconds of actual footage of this app in your movie.

2 KS movie, its aimed at Arduidiots.

3 no knobs

you should of thought about that and offered something like
http://hackaday.com/2014/02/04/a-usb-connected-box-o-encoders/

its only plastic box, ~10 encoders and 8 bit micro emulating USB HID keyboard.

All in all the only interesting thing you offer is the app, but I have a suspicion it will be a big letdown because you focused on hardware.
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