Recommendations for cheap oscilloscope and logic analyzer for occasional use - Page 1
Forum section: electronics / testgear

author: midix
author_rank: Contributor
timestamp: February 16, 2015, 08:50:10 am
content: Hi all.Short story: I'm looking for a good entry level oscilloscope and a logic analyzer, preferably both in a single device, for a price less then 200 Euros.Long story.I am a programmer who sometimes happens to have small projects with low level programming, like capturing and processing audio waveforms or interfacing devices via SPI or I2C. I work for a small company and it seems currently I'm the only one who has at least some electronics understanding, so I expect to have more and more electronics related projects dumped on me, and I like that.As I work from home and don't have much space on my table in my small flat, I think a full-featured bench oscilloscope like Rigol or Siglent might be an overkill, and also somewhat too pricey, considering that I'll need also a logic analyzer. Thus I think I'll need something connectable to USB.I have done some investigation and I know that generally USB solutions are not that popular among professionals because of some limitations. But considering that I'll be measuring only low voltage signals (10V range should be enough) and low frequencies (I guess, no higher than 10MHz), maybe a good quality USB scope+logic analyzer would be good enough.I live in Europe, so I'd prefer an option to buy from Amazon.co.uk or Amazon.de or some reputable dealer who delivers from EU because buying from USA will add shipping costs and also some paperwork with customs and taxes. I could also buy from e-bay or China, if only there is anything worth looking at.So, if you know a good quality USB oscilloscope+logic analyzer for less than 200 Euros, I'd really appreciate your advice or any other useful considerations. I could also buy them as separate devices, if there are some good options for the price, but a single device would be more convenient. Unless such all-in-ones are too universal to be goodThanks.

author: lapm
author_rank: Frequent Contributor
timestamp: February 16, 2015, 11:46:17 am
content: Even if you do only need then occasionally, get decent scope. Digital storage scopes are popular and relatively cheap now days.For logic analyzer, you could get saleaes products. Their software is highly regarded often..

author: LaurenceW
author_rank: Frequent Contributor
timestamp: February 16, 2015, 12:37:00 pm
content: One box. Does everything you need. Small, simple, intuitive, includes I2c decoding!http://www.digilentinc.com/Products/Detail.cfm?NavPath=2,842,1018&Prod=ANALOG-DISCOVERY&CFID=7583417&CFTOKEN=10a40aad1e89814-B7620DA4-5056-0201-02FF6063D05119B5Student discounts available from German agents (if applicable)http://www.trenz-electronic.de/Achieves your price point.My only connection with this product/seller is as a happy user/customer.

author: midix
author_rank: Contributor
timestamp: February 16, 2015, 02:42:35 pm
content: Thanks, guys for help.Analog Discovery seems a great tool. It will cost me 250 €, but I guess it's worth it, unless I find other options. I hope to get some money from my boss if my next project succeedsSaleae also seem to be good. I see they put more attention on the digital side, but some of their products have analog inputs. I guess, I'll have to compare them both to see if I can get with Saleae alone for both digital and analog because they are cheaper than Analog Discovery. AD has 16 digital inputs which might be a bit overkill for me, but AD seems to have stronger analog functionality than Saleae devices.It would be great to find some side-by-side comparison of Saleae and Analog Discovery to see which one is better for me, considering also the price.

author: rdl
author_rank: Super Contributor
timestamp: February 16, 2015, 05:35:41 pm
content: I think Dave did review one of the Saleae Logics and I know he looked at the Analog Discovery. It was not a comparison but two separate reviews. I don't recall the episode numbers but the one on the AD was fairly recent. Those would at least give you an idea of what they can do. I personally wouldn't pay the full $250 for the AD but that's your call. I really don't know how much being in Europe complicates getting one, but sometimes just signing up for an online course in electronics or programming will qualify you for the "student discount" or maybe you know an actual student that could help you out.

author: Smith
author_rank: Frequent Contributor
timestamp: February 16, 2015, 06:41:09 pm
content: Just saw the bitscope on the Farnell site today.Looks like a neat little and cheap device (109 euros) . Also seems to have software for decoding and FFT analisys.http://bitscope.com/product/MP01/

author: dadler
author_rank: Unknown
timestamp: February 16, 2015, 07:02:37 pm
content: Take a look at the newer Saleae products. They are implemented on an FPGA vs the MCU in the one Dave reviewed. In particular, they support analog voltage sampling along with digital sampling. This is not like a full analog scope, as you cannot trigger on analog voltages. But you can trigger digitally and then see what was going on in the analog realm.I have the new Logic 8, and it works really well. It might exactly match your use case.A large bonus with this product is the ability to write custom decoders. They give you a C++ class to extend, and you get full reign over the UI in their software. They also give you the source to all the decoders that come with the software (lots of them - I2C, SPI, serial/UART, CAN, list goes on...) The inputs are protected to +/- 25V so most of the time you don't even need a transciever. Can usually trigger/decode wire-level CAN/RS232 in my experience.

author: dadler
author_rank: Unknown
timestamp: February 16, 2015, 07:22:34 pm
content: Pics of my Logic 8 (I'm not affiliated with Saleae, just think this is a great product):

author: nctnico
author_rank: Super Contributor
timestamp: February 16, 2015, 07:48:33 pm
content: I'm watching the Analog Discovery review by Dave (). I like the network analyses feature. With a 14 bit ADC & DAC it has a lot of resolution even though it has only 2 input ranges.The digital analysis part also has some protocol decoding as well.

author: midix
author_rank: Contributor
timestamp: February 16, 2015, 08:25:44 pm
content: Thanks again. I watched some Saleae reviews - most of them about the older devices without analog inputs, but yes, they seem really attractive. I don't want to pay for 16 digital inputs most probably I won't need that many.So, now I'm leaning more towards Bitscope (110 euros) or Saleae Logic 8 Black (199 euros). I'll compare their specs. I'm still a bit new to oscilloscopes but I guess, it's as usual - the higher the numbers the betterAnd both companies feel reputable enough to trust their specifications.And to make my choice even harder, I found also LabNation Smartscope:https://www.lab-nation.com/specsNow I'll have to create an excel table to have a better picture of what is what.

author: dadler
author_rank: Unknown
timestamp: February 16, 2015, 08:28:18 pm
content: Quote from: nctnico on February 16, 2015, 07:48:33 pmWow I was not familiar with this unit. Just watched the video. Has anyone else on here used it for any extended length of time, and could offer a short bullet point review?It has different strengths and weaknesses compared to the Saleae unit, but it looks very capable. The 14bit ADC is tasty.

author: midix
author_rank: Contributor
timestamp: February 18, 2015, 03:11:54 pm
content: Yep, AD is really great and I'd like to see them producing similar devices with less functionality, but with the same quality for a more affordable price. For example, 4 or 8 logic channel devices would be great and just fine for occasional users who need high quality basic all-in-one tool.If Saleae can do it, why Digilent shouldn't do the same?

author: Fungus
author_rank: Super Contributor
timestamp: February 18, 2015, 03:43:48 pm
content: Quote from: midix on February 16, 2015, 02:42:35 pmThe real problem I have with their analog side (apart from the lack of bandwidth) is that there's no real-time display. You can't just poke a probe in a circuit and see what's there - you have to connect the probe, hit 'record', wait a while, hit 'stop' and see what was there while you were recording.That's a showstopper for me.(Please correct me if they've fixed this - I know it's been a feature request for a looooong time)

author: janoc
author_rank: Super Contributor
timestamp: February 18, 2015, 04:12:00 pm
content: Quote from: midix on February 16, 2015, 08:25:44 pmI wouldn't even consider Bitscope. I had one and I am happy I have managed to sell it. The software is quite buggy, the whole thing can (and will) hang you machine at will. And the performance is nothing special. If you need a logic analyser, then the Saleae is a better deal.However, I do recommend you to search the forum, the pros and cons of the Saleae vs. various other options (clones, other analysers) were discussed at length there. If you are only planning to debug I2C/SPI and similar, you don't really need the 100Msp/s capability of the new Logic 8 (SPI goes rarely above 1Mbit/s) and can save some significant money.If you want a scope, then you can pick up an used analog scope for $100 and it will serve you much better than these devices - higher bandwidth, real-time update, real knobs, etc. Again, search the forums, it has been discussed before.The little USB gadgets rarely have usable sample rates and if they do, then they don't cost $100 ... Keep in mind that even for 10MHz bandwith you need to sample at at least 50Msamples/s to get a reasonable idea about the shape of the signal, ideally more than that. Otherwise your square wave will look like a sinusoid due to the lack of the higher harmonics - not very good if you are working with digital signals!E.g. the Bitscope advertises analog bandwidth of 100MHz, but if you look carefully, you will discover that they are only capable of 40Msamples/s sampling - so that 100MHz means the bandwidth of the analog inputs, but in reality you will be able to capture 20MHz max (Nyquist rate) and the really usable bandwidth for non-sinusoidal signals will be somewhere around 5MHz. In addition, if you have multiple channels, the rate is divided by the number of channels in use. Misleading marketing, at the very least - unfortunately very common with these USB "scopes".The other problem are the often primitive frontends, so serious measurements are hard to do/impossible. The cheap USB scopes are perhaps somewhat usable for audio work, but that's that - if you get an used analog scope, you will get much better value.Otherwise, if you have the money, then something like the $500 Rigol DS1054Z is an unbeatable value.

author: Lightages
author_rank: Unknown
timestamp: February 18, 2015, 05:28:27 pm
content: The Analog Discovery looks like a great all round first test instrument, other than a multimeter, for anyone wanting to get into electronics. Dave's review showed how well the analog part works but he skipped over the logic analyzer part too fast for anyone to get an idea how well that part works. I would still like to see a more detailed review on it.

author: rdl
author_rank: Super Contributor
timestamp: February 18, 2015, 06:54:23 pm
content: Saleae does have a 4 channel logic analyzer for about $100 and I guess they have pretty good software, but isn't most of their other stuff a lot more?The Analog Discovery has a 2 channel oscilloscope, AWG function generator, logic analyzer, and other stuff. Yeah, it has a "list price" of $249, but can be had for as little as $99. I guess I don't see how much "more affordable" they can get.

author: midix
author_rank: Contributor
timestamp: February 18, 2015, 09:54:09 pm
content: Here is what I've read in a Youtube comment about Analog Discovery:QuoteSo, as I'm not a student and not from USA, the best deal I can currently get is 250 Euros, and I'll be paying for 16 logic channels. Being able to measure only audio signals on oscilloscope + 4 logic signals is OK for me, so maybe even Saleae will do. Still, if there were cheaper AD models for non-students with the same quality analog inputs and just 4 logic channels, I'd go for it without any doubts.Thanks for sharing your warnings about Bitscope and lack of real-time display for Saleae.I know, Rigols are good entry level scopes, but I just hoped to get analog+digital for the same price. Well, it's time for me to talk to my boss and find out, if we can get Analog Discovery.

author: janoc
author_rank: Super Contributor
timestamp: February 19, 2015, 09:59:19 am
content: Quote from: midix on February 18, 2015, 09:54:09 pmBeing you, I would still consider an used analog scope & separate logic analyser. You certainly could get that for the price of the AD board and would gain a lot more flexibility long term. The AD is certainly a good product, but it is first and foremost meant for education use as an "integrated lab" instrument for teaching of a certain curriculum. It is far less useful beyond that as a general purpose instrument.Having a "real" scope also teaches you much more about your signals and the instrument than pushing some "magic" button in some black-box software. My first scope was a home-made 5MHz single channel affair I got at an amateur radio swap back in the day - it was utter crap, but I have learned so much from using that and especially trying to deal with its limitations!Not having integrated analog + digital mixed signal capability isn't really a big deal for most people - you can always trigger the scope from the logic analyser or vice-versa if you need to time correlate the analog and digital signals, you just won't have the signals on the same screen. I haven't found that I need that all that often, unless you are frequently working with things like ADC/DACs. Even then, if you have a 4 channel scope you can do a lot with the scope alone already, without even bothering with the logic analyser - I take mine out only when I actually need to decode the digital protocols (my Rigol DS1074Z is very clunky at that), otherwise it is faster and simpler to just use the scope.

author: Howardlong
author_rank: Super Contributor
timestamp: February 19, 2015, 10:39:46 am
content: Quote from: midix on February 18, 2015, 09:54:09 pmTake a look at MocrochipDirect, I don't know why, and I am not going to question them, but they have been managing to undercut on the Analog Discovery for a while now. I bought one from them about three months ago.Note that the I2C decode works but it's limited in the amount you can see at any one time due to the capture buffer size. You can play about with the buffer size to some degree.The advertised analogue bandwidth on the AD is very underspecified by the way, it's about 33MHz, reflected by both rise time and 3dB point measurement, but note that triggering tends to be very jittery at higher frequencies, I assume because it's a software trigger.However for such a small very portable unit it is pretty capable, it's my "just in case" tool when travelling light.Regrettably, I've been continually disappointed by Bitscopes, almost entirely because of the software. My old BS50 offered a great package in such a small and rugged case, with reasonable bandwidth and ideal for travelling light I thought. But recently the concurrent mixed signal and AWG capability seems to have disappeared from the software for this device. So a great idea, but the software is underwhelming to say the least. It pretty much remains sat in a drawer 99.99% of the time as a result.Of course, if you can run to it the star of the moment is the Rigol DS1054Z.If I can put it into some perspective of what you're getting for your money, the BOM cost on the Analog Discovery is barely paid for even at EUR250.

author: rdl
author_rank: Super Contributor
timestamp: February 19, 2015, 02:59:23 pm
content: I registered for an edX course on embedded systems and even though it was not required, the Analog Discovery was supposedly available at the $99 price. I don't know for certain because I already had one, purchased, for $99 from Newark during an "engineer's month" special, several years ago. I won't swear to it because there's a good chance I'm wrong, but I seem to recall that around that time all Digilent wanted to qualify for the $99 price was a .edu e-mail address.However, according to their current policy:QuoteThey could probably even argue that by taking an online course, you're technically not "at a US academic institution".I guess the easily available $99 deal was more of a temporary marketing scheme than anything else. That said, $99 is probably an unrealistically low price, and any student that qualifies should grab one without question. It's a no brainer at that price. I think if they sold it for somewhere between $150 and $199 it would still be an incredible bargain. I wouldn't pay $249 for it though. Something about crossing the $200 mark for a USB based device just doesn't sit well with me.edit: though not thought

author: Mark
author_rank: Frequent Contributor
timestamp: February 19, 2015, 03:07:24 pm
content: I have an Analog Discovery which I received as a Christmas present from my lovely wife. It paid for itself the following morning when I was running some tests on a board I am working on. The resistor values fitted to the board were incorrect (1k instead of 120R), so the frequency response was wrong.Some pics below, showing the Analog Discovery connected to the AA filter on the board, incorrect freq response with 1k resistors (-3dB point is too low), then a re-run with corrected values (172kHz).Then I built up a Chebychev band-stop filter with a 741 op-amp, nice response curve, which matched the calculations from a book I was following.2.0 Chassis test shows the Analog Discovery (on the left of my screen) being used to inject waveforms into my board, and the outputs from my board being displayed on our product's software.4.0 Terminal capture shows another product I've been working on, this time using the Digital IO feature of the Analog Discovery to (1) reset the board using a virtual push button, (2) switch the power on the board by driving a relay, (3) monitor various outputs as LEDs on my screen etc. (4) toggle input control lines to an FPGA.4.1 shows the big mess o'wires by having an Intronix LogicPort and Analog Discovery attached to the board.I have also been working on the Zedboard with a bunch of pmods from Maxim.5.1 pmod SPREAD SPECTRUM FFT ENABLED WITH PERSISTENCE shows a spead spectrum clock generator being controlled by the zedboard and the AD oscilloscope showing the wave with infinite presistence, and broad peaks on the FFT."5.2 pmod I2C RTC" shows the Analog Discovery's logic analyzer decoding some I2C from a pmod RTC. You can make out hours, mins, seconds etc."5.3 VHDL sine generator digital and analog" shows a home project where I am generating a digital sine wave in VHDL on an Altera FPGA and feeding it into a DAC. The logic anayzer on the left of the screen shows the digital channels at the DAC input and analog representation, and the oscilloscope shows the output of the DAC.I paid full price for the Analog Discovery from farnell in the UK. My wife was expecting more for the money but I have been explaining for years that great things come in small packages but she obviously hasn't been listening. Overall this little box has been very useful and is a really great "do it all" instrument whether you want to experiment with filters on a breadboard, or debug something in a work environment. It goes without saying it is very portable, so it has been fun playing with filters etc on a breadboard having the Discovery connected to a laptop.As with all of these USB devices, the PC software makes or breaks the product. In this case, Digilent's Waveforms suite is awesome - very nicely designed and easy to use. Haven't managed to crash it yet.

author: Howardlong
author_rank: Super Contributor
timestamp: February 19, 2015, 04:36:24 pm
content: Quote from: Mark on February 19, 2015, 03:07:24 pmNow that's nerd porn. I trust your wife's OK with that!QuoteAgreed, it is pretty good. My main complaint, if I am allowed, is the memory depth, or the lack of it.

author: Harrkev
author_rank: Contributor
timestamp: February 19, 2015, 09:04:54 pm
content: One more comment... Space and convenience. I do not have the space for a "full" workbench. I actually do have a rather nice mixed-signal oscilloscope, but would still like to get the Digilent Analog Discovery setup just because it would leave SO much more room on my desk. Plus, I could also throw it in a laptop bag and take my setup to a coffee shop.