RoadTest: Picoscope 2205A Oscilloscope
Author: migration.user
Creation date:
Evaluation Type: Independent Products
Did you receive all parts the manufacturer stated would be included in the package?: True
What other parts do you consider comparable to this product?: Benche scopes from Rigol or Owon.
What were the biggest problems encountered?: null
Detailed Review:
This is my review of the Picoscope 2205A, a USB oscilloscope with 25 MHz bandwidth, 2 channels and a built-in function generator.
I build and tinker with electronics for both fun and work and I'm also active in the Attraktor hackerspace in Hamburg (Germany), where we have regular meetings about electronics, give talks and organize events around that topic. I will mainly look at the Picoscope from a hobbyist and hackerspace perspective, building small microcontroller projects and reverse engineering things that you want to modify or tinker with.
I'm interested in:
I really, really, _really_ like oscilloscopes. They're by far the tool I like the most in electronics. 
So far, I have only used bench scopes before. I started many years ago with a small single-channel analog scope. Currently, my main work scope is a rather nice and modern mixed-signal one.
This is the first time, I'm using a USB scope, though and i was always a bit skeptical about them. But mainly, just because I like turning knobs ;-)
Some advantages I expected for USB oscilloscopes in general
Some disadvantes I expected:
This is the first time i review a piece of test equipment and I hope there are not too many errors/omissions in this review. If you find any, please tell me and i will correct them...
So let's start...
Looking at the specs and line of products, the 2205A is one of the smallest scopes Pico Tech makes. It costs around 240 Euros and offers 2 channels, 25 MHz bandwith and a built-in function generator. Another notable feature is the serial decoding included in the software. Pico uses the same Picoscope software for all their scopes up to the quite impressive 6000 and 9000 series.
The price for the 2205A is about the same as for the Rigol 1052A, a very popular 50 MHz bench scope or an Owon SDS5032E (30MHz), both chinese brands.
The packaging, a simple brown cardboard box was easy to open and neatly organized.
It contained:
No printed manual, but that's usually the case these days and saves paper. I like printed manuals but you get more recent copies anyway if you download PDFs from the website. The Pico website offers a User's Guide and a Programmer's Guide as well.
The USB cable is of very nice quality and quite long. Useful, if your PC is stored under your workbench since you need the scope box near to where you work.
It did not come with any test report or calibration certificate which disappointed me a little. Even the cheap chinese equipment i have usually comes with a calibration/QA report, even it's not a real tracable calibration. I also did not find any mention of a self-calibration function or calibration recommendations in the scopes' documentation. But it seems Pico offers a calibration service.
The scope box has a very good build quality and feels really sturdy. I could probably stand on it without breaking it (I didn't try it, though..). It can probably also take a drop from 1-2 meters without any problems. The BNC connectors are quite sturdy as well. This is really a well built device that can take every day mobile use and being stored in a tool bag.
All input are clearly labled. Two BNC for the scope channels and one for the waveform generator. No BNC for trigger in/out, though.
The scope box is USB powered and does not require a separate power supply. That's quite nice since that means you can power it from a notebook and really take it outside to debug your quadrocopter or sensor installation in the woods.
I noticed two things...
The channels use the same ground as the USB connector. This is not much of a surprise since the scope needs power and ground and the USB port is the only way it can get it. It the scope had a dedicated power supply, it could use that for ground and completely isolate the USB port so you don't run a risk of blowing the USB port on your PC because of a measurement error. A quick check on my bench scope revealed that it also doesn't isolate its USB or LAN port, but at least it has a good ground connection via its power cable. This also means, if you use a notebook on battery and the device you test is also not grounded on it's own, the scope is floating without any reference to real ground.
This is probably also the reason for the other thing I noticed: You can only measure voltages up to 20 Volt Peak-to-Peak.
Looking into the User's Guide of the Picoscope, you find almost two pages talking about safety, maximum voltage and grounding issues and quite few of those paragraphs contain the phrase "To prevent personal injury or death". Yes, I'd like to prevent that...
The manual also advises to use an isolated differential probe to measure higher voltages and Pico offers quite a number of those, but unfortunately, even the smalles one costs more than the whole 2205A scope and they go up to almost 1000 Euros.
http://accessories.picotech.com/active-oscilloscope-probes.html
So, while grounding and safety are always an issue with scopes, for a USB one without dedicated ground it's even more of an issue. To protect yourself and your equipment, always keep this in mind and better only measure low voltages.
The scope comes with to PicoTech MI007 60 MHz probes so they have more than enough bandwidth for this scope. They have a 1:1 <-> 1:10 switch.
The probes are also of a very nice and sturdy build quality. Good quality plastic, very nice coax, good BNC plugs. The probe tips are quite sharp and not spring-loaded.
They come with a small bag of accessories that contains:
A few more accessories would've been nice, especially a BNC adapter for the probe tip as these are usually vendor specific. None of the ones i have fit. The metal ring below the probe tip has a diameter of 4.8 mm.
What's nice about the probe is it's price. If you ever need a replacement probe, you can get one for under 20 Euros which is a very good price for such a well-built probe, even if it does not include many accessories...
The installation of the PicoScope 6 software under Windows 7 was without problems. It produced quite a number of "do you want to install this device driver" dialog boxes but apart from that it was quick and without any problems. Also, no reboot was required before i could use the scope...very nice.
The software contains an automatic update mechanism and will offer upgrade if a new version of the PicoScope Software is available.
You can get 3 manuals for the scope. The hardware manual for your specific scope which is ~20 pages long and mainly gives specs, safety infos and how to connect the scope. The User's Guide for the PicoScope 6 software which is around 200 pages long and explains the software in a lot of detail. The Programmer's Guide, if you want to remote control the software by your own programs. Probably very nice for writing test systems or automated service and debugging tools. At least the User's Guide is available more languages: italian, spanish, german and french. I didn't read the User's Guide cover-to-cover but every time i looked for something i found the information quickly.
The main specs of the Picoscope 2205A are:
For the integrated function generator you get:
For most beginner hobby products (that dont require HF stuff) the 25 Mhz bandwith should be enough. It will allow you to learn about general electronics, check the signal quality of digital signals (like I2C, SPI) or check/debug circuit boards.
However, when i did a quick check of the 3 dB point with my function generator, it was somewhere around 12 MHz an i had 3,5V of 5V left, at 25 MHz, the waveform was down to 2 Volts. This means that this 25 MHz scope effectively only gives you 12 MHz of real bandwidth. I hope i made a measurement error somewhere, otherwise this would be a really bad result... (If I find the time to carefully redo and check that measurement, I'll update the review..)
The 20 Volt Peak-to-Peak are considerably lower than what you get on a tables scope (which you normally get on bench units).
When i first started to use the Picoscope, i plugged it into a USB hub that's sitting on my desk. Even though the hub has its own power supply, the Picoscope was not correctly reconginzes by my computer. After i plugged it directly into my notebook, it worked fine.
When i started the software for the first time it automatically updated itself to the newest version (didn't need long) and then offered the main screen.
The user interface is available in various languages, the Germany translation however was a bit uneven and could use some polishing from a native speaker. The software does not require any product registration or license key nonsense, which is nice.
The software offers one large view that is dominated by the waveform display. For different tasks the UI changes just slightly.
The UI elements for controlling the scope are in top and bottom toolbars and both in function and in layout very different from the typical layout of bench scopes. Also, they're all quite small to outright tiny and many of them are hard to read. One reason may be the high resolution of my notebook (1920x1200) but both the control as well es the text (e.g. axis labels) should be bigger.
The controls for controlling the the channels of the scope, the scope mode and pan/zoom are in the top tool bar. The controls for tringgering and measurements on the loer tool bar.
Most controls work ok if you know what exact value you want to set them to, but tuning and "looking around" is hard this way. The UI largely relys on drop-down-menus and text boxes. No sliders or rotary controls to gradually set a value. The designers of this UI should take some inspiration from DJing software or other software meant for live performance or studio work. That type of software really tries to emulate physical equipment with lots of knobs and sliders and usually works quite well.
Also, the software does not stick closesly to the Windows UI model or the functions that most programs provide. Again and again I tried to do pan/zoom with drag&drop and by using the mouse wheel.
Overall, while everything is there, the usability and interface of the software could use a lot more work and polishing and at least i would like it if it would more directly emulate the layout and operations model of a regular bench scope and stick closer to the Windows UI guides.
The main advantage of the UI is that you can have different views at the same time. You can look at different parts of the wave form (or in different zoom levels) and also look at the spectrum or XY view. This is very nice for giving talks since you can show all the interesting parts at the same time.
The scope offers waveform view, spectrum view and an XY view of the waveform. You get cursors and measurements, various trigger modes and triggers.
The software offers quite a lot of measurements for each of the views. When you activate them, the UI shows all of the activated measurements in a list at the bottom of the screen, complete with statistical values like min, max, average and deviation.
The cursors do not offer waveform tracking and i found them quit cumbersome to use. Very small handles, laggy response...
The triggering is done in hardware while the measurements seem to be done in software. This would also explain why the software enters quite a number of measurements but only a few triggers types. Additional triggers would requires expensive changes in the hardware, new measurements can more cheaply be done in software. This also means that anything that the software calculates (e.g. the serial decoding, math functions) can not be used for triggering. The values are only available in the software and not in the triggering hardware.
The scope offers only a limited set of triggers. Mainly variants of level triggers and a few interval triggers. I would've expected more..
The math functions however are very powerful. When you first open up the dialog, it only gives you addition, subtraction and one or two others. But then you notice that this is just a list of predefined examples and that you can open a formula editor to create your own math waveforms from simple to very complex. This is a very powerful feature, but since its done in software again it suffers from that you can't use the math function as a trigger source.
The software offers serial decoding for CAN, I2S, I2C, RS232, SPI, LIN & FlexRay which is quite unusual for a scope in this price range an one of the major advantages. Usually it's only available for the bench scopes beyond 1000E and has to be licensed via an extra option (and that's not cheap).
I tried decoding some SPI commands sent from a microcontroller and it was easy to set up and worked instantly (once set got the data mode correctly).
While the serial decoding function itself is very useful, it loses most of its usefulness on this very small scope which has only two channels. For most serial protocols you need two signals (e.g. clock & data) which means that both of your oscilloscope channels are in use and you cannot look at an analog waveform at the same time. Again, since decoding is done in software, no triggering from the decoded data (or any other property of the digital protocol). Which means that you have to trigger off one of the digital signals, which, together with the limited set of triggers leaves you with little choice but to trigger from the clock line, e.g. start of clock, end of clock.
Serial decoding together with analog triggering can be quite useful, e.g. to see what I2C command was sent directly before your DA converter starts doing strange stuff or what happened on an analog input line just before your IC sends an error command. All this is not possible if you have just two analog inputs and not digital ones. The 2205 is also offered as an MSO version with digital inputs and with that model the serial decoding feature would be a lot more useful. With the 2205A, the functionality is so hindered by the 2 channel limit that its hardly of any use in practice....
The AWG offers waveforms up to 100kHz. Apart from the AWG, you get Sine, Square, Triangle & Ramps and a few others.
You can set set sweeps over frequency ranges and make the AWG start when the scope triggers but unfortunately, you cannot (internally) trigger the scope based on the AWG. Also, no modulation and no sweep state output.
One big downside is that you cannot see the AWG output or trigger on it in the software unless you probe it with one of the scope channels. But then you lose one of your two channels again. This is understandable because having a back channels for the AWG output into the PC would effectively be a third channel, but again, this restriction makes the integrated AWG much less useful than it could be.
I did not test all the functions of the scope. For example it also offers mask tests. If you want a detailed descriptions of all the functions, please have a look in the manual that's available on the Pico website.
One spectacularly useful feature is the programming API.
I just had a look trough the API and the provided (extensive!) sample C code and did not have the time to try it out myself. But this is where a PC-based scope really can shine. You get access to the buffers, can configure the scope can use it to automatically collect sampling data or control the AWG. A quick scan through the C header file looks like you basically can do everything automatically that the UI allows you to do manually. This is very nice for doing more complex tests or long time debugging and while bench scopes ofter offer this as well, you have to spend a lot more on a bench scope until it offers this level of remote control via USB or Ethernet.
While the PicoScope software is a Windows software, Pico is also preparing a Linux version that can already be downloaded as beta version. I tried it under OpenSUSE 12.3 (it even came nicely packaged in an RPM).
The software is not a native Linux application but a .Net binary that is run via Mono. While that makes it a little performance hungry, the Beta version already works quite well.
Not all functionality is there (e.g. serial decoding and math are stillmissing), it was stable and overall very usable. Since Linux is my main OS, this is a very big advantage for me. I can easily use it on my work bench and take it to workshops and conferences and just use it. Nice!
The installation was almost flawless and the software is quite stable (just don't pan/zoom around too quickly 
). It feels like the software is around 70% complete and i hope Pico will release a full version within the year.
You can use a scope in many different scenarios (Hobby, Professionally, Hackerspace) and for different purposes and of course for some it's better
suited than others...
On your workbench, you can use a scope for development, testing and debugging.
The Picscope UI works best when you know exactly what signals and voltage levels you expect where. This is the case if you do regular "engineering style" hardware development and even more so if you to testing/verification or debugging of your own designs. Set what you need in the drop downs and look if the device shows what you expect. In these scenarios the Picoscope software works quite well and for testing/verification you can even have lots of prepared settings/masks/math-functions that you just load and use. If you just need to make sure that everything is ok and check a few testpoints with predefined scripts, the Picoscope will be a very easy and quick to use tool.
This is less the case if you're learning about electronics. If you're just starting electronics or learning scope operation, the missing "tunability" and overall fussy UI will slow you down a little and may even make you miss signals. If you're a learner, another downside is that most learning materials (books, websites) will assume you have a regular bench scope and describe its use in terms of the knobs and buttons you usually find.
For reverse engineering or repairing unknown systems (without service manual), the UI is even less suited. If you don't know yet what's where, again the UI will slow you down.
The small USB box may save some workbench space if you alread have a PC on your workbench. But even then you probably also use that PC to display data sheets or use other measurement software. If you have just one monitor, you will have to switch between views quite often and it will be difficult to compare waveforms with references in datasheets. If you have to add another monitor or PC to your workbench to use the USB scope and all that space saving advantage is gone. Also, a bench scope is easy to carry around. If you just have a PC not a notebook, your USB scope is pretty much stuck to the PC.
I'm part of the Attraktor hackerspace in Hamburg and most of our scopes are a little dated and quite big and heavy. So i wanted to know, how useful is a Picoscope in a hackerspace?
As a general work scope it turned out to be quite useful. This is because most people bring notebooks and work all around the space. If you need an oscilloscope, just get the small box and take it to whatever work place you need it. No need to carry around the big scopes and since table space is always rare, it even may save a seat that would otherwise be taken up by the bench scope. This is even more the case for workshops when the hackerspace is crowded. However, since the Picoscope is not very inutitive if you have never worked with a scope, I would not use it for a beginners course.
We often have talks at the hackerspace or go to events (like Makerfaires or workshops at other places).
Until now, we usually used a webcam and pointed it at the scope when we wanted to show waveforms on the projector. This was not so nice since the cameras had a poor resolution and fps. Some modern bench scopes offer a VGA output, but none of our scopes has one. Also, a speakers desk is usually quite small and a big bench scope is not easy to fit and handle.
A USB scope is small and can directly be attached to the speakers notebook. It offers a much better picture quality for both resolution and FPS. The students can much more easily recongnize the waveform. However, again the Picoscope UI is a problem. Since many the controls and axis labels and control elements are so small, you can see the waveform clearly but hardly any of the text. It would be nice if the UI had a "presentation mode" where bigger fonts are used so you can recongnize everything even on a projector.
And last, but not least, since this a roadtest, how useful is it no the road?
If you are a service technician I'd expect the Picoscope is a great tool. Since the UI works best if you clearly know what you need to do (and ideally have saved settings, waveforms/masks, scripts) you have a small and very portable scope to use in the field, check testpoints on equipment and quickly determine whats wrong. Actually, I suspect that use by field technicians is actually the main use case of the Picoscope hardware and software and really what it was developed for....at least it feels like it.
I am not a service technician, but i took the Picoscope on two trips (and am actually on a train while using it on a microcontroller and writing this review). I also took it to Makerland conference in Poland and it proved useful and easy to carry around both on the train and at the conference...just boot my notebook, plug in the scope and I'm ready to go (strange looks from other people on the train included...)
Soo...how was the road test? Did i like it? Should you maybe consider one, too? The Picoscope 2205A? A different one?
Well it really depends on what you want your scope for...
USB-Scopes like the Picoscopes are nice if you want:
However, i am really not that happy with the usability of the Picoscope software. While most of the functionality is there, it feels like a software developed by engineers without any UI designer involved. If you need/want to fiddle, tweak and tune a lot, this becomes annoying. Pico could easily make the software much more satisfying to use if they gave the UI an overhaul from a specialized UI designer and more attention to detail, maybe even different modes, where one trys to mimic the scope layout people are used to and another more Pico-specific.
If you want a proper all round every day bench scope with a lot of functionality, I would not really recommend the Picoscope 2205A and, since the PicoScope software seems to be the same for the bigger models, this may be true for the them as well.
It's a nice portable service/testing and a good "second scope" but it simply doesnt feel like a "proper" scope, more like a smaller version for mobile use where you cannot take a bench scope.
Many of the previous are not just true for the 2205A but also for the other Picoscope models and the concept of a PC-based USB scope in general.
And the 2205A itself?
It seems Pico may pushing the price a little bit too far here. While 240E is a very good price, the model feels like it is very cut down to actually reach this price.
Only 2 channels and no digital channels cause the problems i described above. There is not much memory and the sampling rate is also not very high and it does not many different triggers. Some of the features, like the AWG and the serial decoding are there but feel so cut down that their usefulness really suffers.
If you would like a portable USB scope i would recommend you get at least the MSO variant of the 2000 series. It offers 16 digital channels so you can to full digital decoding and still have your analog channels left for triggering. With 360 Euros the MSO variant is unfortunately 50% more expensive than the 240E for the 2205A, but in my opinion it's worth it.
Currently, about 300E seems to be the price limit for an oscilloscope. If you spend less, it'll start missing crucial features and be pretty restricted in it's specs.
So, is the Picoscope 2205A worth the 240E? Yes, I'd say so, but I'd also recommend spending a little more and getting a lot more out of it.
If a company offers such a low end scope, it its probably targeted at hobbyists and makers who don't want to or cannot spend a lot of money on a scope (or a very basic scope to give to every maintenance technician you have without paying huge amounts of money). Since these people mostly work with microcontrollers and specialized ICs connected via SPI or I2C, i would suggest to leave out the AWG and make a smaller MSO model that offers 8 or maybe even 4 digital channels. This would be a nice if somewhat limited hobbyist scope to work with Arduinos or other microcontroller platforms.
If a USB scope is the right choice for you really depends on what you want to use it for....
Anyways...i hope this review is helpful to you. It certainly was fun to try out the Picoscope and I've always wanted to test what an USB scope is like. I'd also like to thank Pico Technologies and Element 14 for the Roadtest and providing me with the scope.
