EEVblog #485 - Agilent TrueVolt 34461A Multimeter Teardown

[Monkeh]

Just remember that WinCE has virtually nothing in common with Windows.

[FrankBuss]

Acutally WindowsCE is not that bad. Unlike Linux (if you don't use LinuxRT, which has its own problems) it is a hard real time system:

http://blogs.msdn.com/b/mikehall/archive/2009/04/23/ce-6-0-hard-real-time-embedded-o-s-here-s-the-proof.aspx

And unlike for Windows XP or other Microsoft systems, you get the source code of the kernel, too, and you can modify it as you like.

I've used it for a client product some years ago. The tools for it were not so good (e.g. I had to write my own "ps" and "kill" programs), but the product works for years now without problems. Yes, it costs more than Linux (depends on the volume, but below $10 per system), but if you have a BSP for your platform, developing software for it is less work than setting up a Linux system on an embedded system. And an embedded version of .NET works on it, too. I was able to write VB and C# applications for it.

[Ronald1962]

Hi Dave,
did you watch the movie "War  Games"?
Cause you tried to type in "joshua".
Nice teardown!
Greets
Ronald

[Monkeh]

Hi Dave,
did you watch the movie "War  Games"?
Cause you tried to type in "joshua".

No, he just picked it at random.

[AlfBaz]

A lot of the negativity MS gets in embedded systems usually stems from experience on PC's where users are installing, uninstalling, modifying and otherwise dicking around with the OS. In embedded systems where you don't ever see the os, if it works when it leaves R&D it generally always works. Over the years with windows CE and just plain windows based products running hidden in the background, nearly all failures I have seen have been due to some physical aspect of the system that would cause problems for any os

[orin]

Wow, Dave, what a fun little comment thread this video has. I think I've heard enough about current through capacitors for a month or two 

Does current "flow through" a capacitor?
NERD FIGHT! 

I just contemplated doing a Fundamental Friday on this, but it's probably just one big huge can'o'worms, and I would almost certainly get some technical detail "wrong"...

As a matter of computational convenience, Maxwell considered "displacement current" to flow through a capacitor and we use that computational convenience today. Certainly a lot easier to think of it as "real" current than a mathematical construct.

Walter Lewin at MIT explains this well.  It is a bit mathematical though. See his lecture on OpenCourseware: http://ocw.mit.edu/courses/physics/8-02sc-physics-ii-electricity-and-magnetism-fall-2010/maxwells-equations/the-displacement-current-and-maxwells-equations/

Hopefully the link works.  If not, search for 'open courseware displacement current'.

BTW, it's well worth watching the entire MIT 8.02 lecture series by Walter Lewin on OpenCourseware, just for the demos if nothing else.

[nitro2k01]

THAT ARGUMENT! All I can say is, theoretical physicist, meet the electrical engineer!

[ejeffrey]

You can't dismiss something as wrong because a person smarter than you said it is true.  I am sure there is a name for that logical fallacy, but I don't remember it.

In any case, the answer is simple.  Current flows through a capacitor.  From a physics perspective the reason is that it isn't worth naming something that isn't a conserved quantity.  You need to add the displacement current term for current to be a useful or meaningful term.  From the EE perspective, if you don't count it kirchoff's law is wrong and you can't do electronics.

[don.r]

You can't dismiss something as wrong because a person smarter than you said it is true.  I am sure there is a name for that logical fallacy, but I don't remember it.

In any case, the answer is simple.  Current flows through a capacitor.  From a physics perspective the reason is that it isn't worth naming something that isn't a conserved quantity.  You need to add the displacement current term for current to be a useful or meaningful term.  From the EE perspective, if you don't count it kirchoff's law is wrong and you can't do electronics.

Appeal to authority?

We were taught that, for all practical purposes, the current flows through the capacitor.

I would still like to see if someone could test whether the fan on or off causes fluctuations in the LSD.

[chickenHeadKnob]

Acutally WindowsCE is not that bad. Unlike Linux (if you don't use LinuxRT, which has its own problems) it is a hard real time system:

 And how long did it take micky soft to get real time working? If I recall correctly version 3.0 or more, it took them years to get this. Small companies that bet the farm on WinCE because they didn't know what they were doing and trusted the  microsoft brand lost big.

A multimeter needs WinCE in the same way a guinea pig needs armor:

[jancumps]

Wow, Dave, what a fun little comment thread this video has. I think I've heard enough about current through capacitors for a month or two 

The only really practical knowledge I got out from that is that it is extremely difficult in YouTube to follow a thread in the comments.

And how long did it take micky soft to get real time working? If I recall correctly version 3.0 or more, it took them years to get this. ...

That doesn't really matter, does it?

[chickenHeadKnob]

Wow, Dave, what a fun little comment thread this video has. I think I've heard enough about current through capacitors for a month or two 

The only really practical knowledge I got out from that is that it is extremely difficult in YouTube to follow a thread in the comments.

And how long did it take micky soft to get real time working? If I recall correctly version 3.0 or more, it took them years to get this. ...

That doesn't really matter, does it?

Yes Jan it does. You may have been asking a rhetorical question but in software development of an embedded operating system the one thing it has to get right is predictable low latency response time, everything else is secondary. That they couldn't get even this working in years time frame while at the same time having available abundant open source examples shows both deep incompetence  and willful disregard for their naive customers. It also speaks to the fact that the typical development cycle within microsoft is to push out steaming bloated piles of accreted bugs on a schedule dictated by business strategy rather than product quality. There is the additional mendacious habit microsoft has in 'churning the API' , it is an official Gates inspired dirty trick, among many. Product life cycle for embedded machines can be 20 years, good luck in trusting microsoft to not bugger with .net or any other API to keep the customers slaves in line.

[dr.diesel]

A multimeter needs WinCE in the same way a guinea pig needs armor:

     , couldn't agree more.

[jancumps]

That doesn't really matter, does it?

Yes Jan it does. You may have been asking a rhetorical question ...

Nono, it was meant as a real question.
The meter running CE 6 does not know what CE 3 was like. That was why I asked this.

[NickS]

Nono, it was meant as a real question.
The meter running CE 6 does not know what CE 3 was like. That was why I asked this.

A Multimeter also doesn't really need to be realtime either. 

It really comes down to experience. IMHO a simple multimeter display really doesn't need the price overhead of WinCE.
But if that is all the manager who's decision it was knows then it was probably the better choice.

Now for a discussion on the competency of that manager......... 

[EEVblog]

IMHO a simple multimeter display really doesn't need the price overhead of WinCE.
But if that is all the manager who's decision it was knows then it was probably the better choice.

Who thinks this is a "simple" multimeter?
It has USB interface, file systems, Ethernet, a huge graphical user interface display that does all sorts of stuff etc.
It needs a complex high level O/S to operate this stuff.
Also, remember that the WinCE platform decision would have been made a long time ago, way before this meter was even though of.
You can't just go picking and choosing the latest flavour of the day O/S for your new product, that would be silly. Any smart company choses an O/S platform very wisely and then stick with it because they become heavily invested in using that standarised O/S platform across their products.
So anyone who's criticising the use of WinCE really needs to understand not only why the decision was made (which can be many many reasons), but also when, and over what range of products it's intended use was.
And when you do that, the choice may not be at all as silly as you think, or a bad one. In fact it may have been the best choice.

[Rufus]

The X 2000/3000 scopes also run WinCE - and we know how rubbish and hated they are.....

The 61A boot time is pretty much the same as the scopes. A lot of the time it claims to be initializing and verifying hardware so maybe it is doing something useful. Quicker would of course be nice.

[dr.diesel]

So anyone who's criticising the use of WinCE really needs to understand not only why the decision was made (which can be many many reasons), but also when, and over what range of products it's intended use was.
And when you do that, the choice may not be at all as silly as you think, or a bad one. In fact it may have been the best choice.

Then you must be willing to accept the USB and LAN functions would be forbidden in some corp environments.  I have worked in two huge corporations that forbid a Windows OS that could not run the corporate antivirus, absolutely no exceptions.

In these cases Corp IT doesn't care or understand the differences between the versions, any alteration would take an act of God to bypass.

[rsjsouza]

And how long did it take micky soft to get real time working? If I recall correctly version 3.0 or more, it took them years to get this. Small companies that bet the farm on WinCE because they didn't know what they were doing and trusted the  microsoft brand lost big.

In my experience, everybody took years to do things right for embedded, and I know a lot of small companies that paid through the nose to embed Linux into products that never saw a production run (some went belly up big time).

Working with different flavors of Linux for almost 20 years, I can tell that only in a somewhat recent time (maybe five/six years ago) is when high level OSes started to be effectively offered to "non-wireless" applications such as this multimeter. I recall that, back in 2005/06 timeframe, it was financially more viable to choose WinCE for low-volume applications (up to 10k/yr) than jump into the embedded Linux bandwagon, where companies charged a lot for technical support and porting work to specific hardware boards (the famous BSPs) - nothing like the free BSPs available nowadays.

As Dave mentioned, if this decision was made years ago I also bet it was the smart decision.

[EEVblog]

Then you must be willing to accept the USB and LAN functions would be forbidden in some corp environments.  I have worked in two huge corporations that forbid a Windows OS that could not run the corporate antivirus, absolutely no exceptions.

What's that got to do with designing test equipment? 

[ejeffrey]

Then you must be willing to accept the USB and LAN functions would be forbidden in some corp environments.  I have worked in two huge corporations that forbid a Windows OS that could not run the corporate antivirus, absolutely no exceptions.

In these cases Corp IT doesn't care or understand the differences between the versions, any alteration would take an act of God to bypass.

Then those corporations are stupid, plain and simple.  Also, this is very rarely true.  A corporation that can't set up a private T&M network segment should fire their IT department, shut down the company, and burn their building down.  Agilent developing a custom complex RT OS that will be guaranteed to be less secure and more buggy than WinCE just to satisfy some imaginary corporate rule would be stupid.

[cthree]

Windows CE is not Windows.

[duskglow]

It has the name Windows on it.  For people who don't know or care to look further, it's Windows.

[cthree]

Acutally WindowsCE is not that bad. Unlike Linux (if you don't use LinuxRT, which has its own problems) it is a hard real time system:

 And how long did it take micky soft to get real time working? If I recall correctly version 3.0 or more, it took them years to get this. Small companies that bet the farm on WinCE because they didn't know what they were doing and trusted the  microsoft brand lost big.

You state the point but fail to understand it. The point is they did get it, it works and has done so for a very long time.

I suspect those small companies than went under were just shitty companies. I worked for one such company who bet the farm on VxWorks and they went under. Was that Microsoft's fault?  No, it was the dumbasses that ran it and built a product nobody wanted to buy, more than one in fact.

Windows CE is nothing like desktop Windows. It's called that because the marketing dweebs at Microsoft *cough* Bill Gates called all their operating systems, after DOS, Windows but that doesn't mean they were different variants of the same code base. Post DOS, Microsoft had 3 separate operating system kernels. Windows 95/98/Me, Windows NT/2000 and Windows CE. Windows 9X/Me and Windows NT/2000 shared much the same Win32 user level API but ran on different kernels requiring different device drivers. I wrote drivers for both, they were entirely different APIs. Windows CE had its own user level API which was entirely different code but followed similar conventions as this was supposed to make skills transferable.

The Win9X platform was dropped and the NT platform became the sole PC OS kernel with Windows XP. Windows CE remains its own OS. I don't know how much of the code base is shared between the NT and CE platforms but probably very little if any.

Stop talking about Windows CE like it has anything to do with Windows, the desktop OS. It is wrong. Windows CE is mature and highly reliable and has a crapload of device support out of the box. They don't make a lot of these kind of devices so having most of the code already written and vetted saves a huge amount of time and expense. It is an entirely reasonable choice for this type of application. It would have to be on my short list if I were in charge of this project.

What other viable options are there without making this single, low volume lab multimeter a life's work?  If you've got 5 months to turn this project and only a few people to do it with what are your choices? A lot of factors weigh into such a decision. Licensing, upfront costs, availability of talent, timeline, capital budget, ISO certifications etc.

What would be really stupid is using Linux when none of your other products do and there are no in house skills or experience with it and there is no definite answer as to what is supported or how well. I'm sure Agilent recycled a lot of code (like for USB and network) from existing products. This is lab grade kit. You can't just put any old shit in there and hope for the best. People are using this gear to power billions of dollars worth of investments. People use this stuff to design satellites, power plants, jumbo jets and submarines. You sell a turd and you're finished. Failure is not an option and I'm sure that all weighed in their decision process.

They knew what they were doing.

[Bored@Work]

CE copied some 5000+ APIs from NT. Microsoft was actually very proud that they were having so many NT APIs in CE. I remember being on a Microsoft Windows CE trainingpropaganda event in London some years ago, where Microsoft guys were almost wetting their pants about how great that is.

They certainly didn't implement the APIs from scratch, but copy-n-pasted code from NT.  NT went on to become Windows 2000, XT, ... But I doubt that Microsoft backported and backports every NT/2000/XT/Vista/7/8 bugfix back to CE.

And just because they recoded the CE kernel from scratch in CE 3.0 doesn't make the old code in libraries go away. If you add to that Microsoft's attitude to bugfixes and support (Bill Gates is on record stating that they don't make money from fixing bugs, so they avoid doing it), it isn't so far fetched to call Windows CE just another Windows, not only by name but by suckage.