EEVblog #485 - Agilent TrueVolt 34461A Multimeter Teardown

[Rufus]

Inside the new Agilent TrueVolt 34461A 6.5digit bench multimeter. A replacement for the venerable 34401A.

Photos: http://www.flickr.com/photos/eevblog/sets/72157634225126018/



May as well start the thread.

I previously read a bit about multi slope III, don't know what IV changes.

Agilent's multi slope conversion is more like a slow delta sigma conversion.

You have an integrator with two comparators and inject the unknown current and a + or - reference current so the voltage on the integrator capacitor bounces between the comparator limits. Over time the ratio of time spent injecting + and - reference currents tells you what the unknown current is. Accuracy doesn't depend significantly on anything but the accuracy of the reference current. The comparators don't have to be accurate they just keep the integrator voltage in bounds.

For more accuracy in less time you measure the voltage on the integrator capacitor at the start and end of the conversion period. The current injection ratio gives you the most significant measurement bits and measuring the initial and residual integrator voltage can give you another 8, 9, 10? bits.

The integrating capacitor doesn't have to be stable or accurate, you can easily calibrate it with the reference current.  Dielectric absorption might still be an issue with this type of converter.

The manual recommends using the 10A input for currents over 1A. The 10A input has a fixed 10A full scale range.

Bits left of the board are interesting - wonder if there is another model to come or maybe they are alternate rather than additional parts, perhaps for the 60A? 

[duskglow]

I found the fact that it boots into a Linux kernel and then runs Windows CE on top of it to be really interesting.  No idea how that works.  Or is that booting Linux on one of the other ARM chips on the main board?

[Rufus]

I found the fact that it boots into a Linux kernel and then runs Windows CE on top of it to be really interesting.

I don't think it does. U-boot describes the boot image as "ARM Linux Kernel Image". Doesn't mean it actually is.

[duskglow]

Huh.  Guess so, at that.

[don.r]

Would the fan not cause some issues with the temp stability around the ref or does the cage and low tempco resistors take care of that?

[Dave]

Does anyone know why both the 10A and 3A current ranges are protected by 11A fuses? Does that fuse really protect the 3A input?

I also want to point out a factual mistake at 23:07: "... you can then switch it back down to ground and it's gonna discharge ...."
If you connect the input of an integrator to ground, no current will be flowing - it won't discharge. I think this calls for an annotation.

I was just hoping to see you connect it to your voltage standard. Guess we'll have to wait for the review. Looking forward to it.

[Monkeh]

Does anyone know why both the 10A and 3A current ranges are protected by 11A fuses? Does that fuse really protect the 3A input?

There's a cheap 3.15A fuse on the back to blow first. The 11A fuse internally is in case of a fault which that dirt cheap fuse can't handle.

Used to be seen on handhelds, too.

[c4757p]

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 

[EEVblog]

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"...

[c4757p]

Oh god.  I can only imagine the results of digging up this one again.



If you value your sanity, don't go anywhere near that.

Fundamental Friday as a whole seems to have started a good few nerd fights. Never underestimate the ability of a pair of jackasses to argue about things that should be established facts...

By the way, at 12/page, this forum is about to reach critical emoticon mass. I suggest nobody use any for a few months or so.

[Dave]

Well, we might have gone a bit overboard on that. I in particular.
But it was an interesting discussion, was it not?

[Harvs]

I never read youTube comments but given the interest I took a look.  Can I get a refund on those 30sec of my life?

[ddavidebor]

Sure, i've read your post.

Now we have a debt of 30 sec each other, so, no debt.

Happy? XD

[duskglow]

Is that Kirchoff's law for debt?  All debt going into and out of a post equals zero?    Is this debt flow or displacement debt?

*ducks*    

[free_electron]

Does current "flow through" a capacitor?

Current flows in and out of a capacitor. But it does not flow 'through' (apart from some dielectric leakage)

[bexwhitt]

Is the current flow through a capacitor like the electron hole, sort of a thing what works in reality?

[FrankBuss]

Looks like Agilent uses the same boot sequence like in some of their oscilloscopes, with u-boot starting WindowsCE. With the scopes you can actually stop the u-boot booting process with enter on the RS232 input, and then you get some commands with "help" (you can't do anything when WindowsCE has started, then it's just a debug output). It is even possible to load and start a WindowsCE image from network (at least with the scopes), if someone wants to play with it

[uprightsquire]

Does current "flow through" a capacitor?

Current flows in and out of a capacitor. But it does not flow 'through' (apart from some dielectric leakage)

And then there's the fact that 'current' in a wire isn't really even 'flowing' through the wire anyway. Net electron velocity is on the order of 1.0 × 10-5 km/hr or something.

Maybe we can start arguing about that whole conventional current flow deal. 

[dr.diesel]

Maybe we can start arguing about that whole conventional current flow deal. 

Let's add what religion is best also! ha ha.

[bktemp]

I wonder how the digital rms measurement works.
I would have expected a fast high resolution ADC (16bit+, a few MS/s) feeding the data into the FPGA which calculates the rms value, but there are only the two low resolution ADCs.
Does somebody know, how it works? Are they using these low resolution ADCs with oversampling to get an accurate AC measurement or is there some other analog magic happening there to get the rms value?

[JackOfVA]

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.

[AlfBaz]

Maxwell considered...

Bah! What does he know, He couldn't even make decent tapes cassettes 

[rsjsouza]

I am pretty sure the mysterious battery manager TPS65073 device was used due to pre-existing device drivers on the embedded OS (WinCE).
These power management devices are very complex and probably Agilent did not want to spend much time in modifying this specific low-level device driver (TI has reference designs for their own SoC processors, where this device controls multiple power outputs)
The serial port is what one would normally get when booting any embedded OS on these embedded computing boards (BBone, RPi, etc.). As FrankBuss mentioned, however, the command prompt is disabled in WinCE unless you interrupt the u-boot sequence.

[RobB]

Looks like an impressive bit of gear. Just a couple of quarms with it though. the first is the extensive use of complex plastic parts. Surely that is not good for long term structural integrity. Take the power switch link for example, it clearly distorts when used. Try that again in 10-15 years and I'm tipping a failure.
Second I am loathed to trust any mission critical hardware managed by anything Micro$oft.  The communists like Rigol et al got it right on this one using an open sourced operating system.

[duskglow]

In their defense, Microsoft's OS really is not on the critical path on this one.  Since the data acquisition is done in hardware and the only real purpose for the OS to coordinate the *display* of that data, it's likely that any failure mode exhibited will be pretty obvious.  I would consider the odds of the WinCE software actually screwing up the display such that it displays the *wrong* value to be really small.  I would consider the odds of it crashing to be much higher.

I share your distrust for MS software but in this particular case - unless the mission critical aspect is 100% uptime, I'm not too worried about it.

[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.

[cthree]

You base all of this on a sales pitch at an event some years ago? I actually fully evaluated WinCE along side VxWorks and we choose VxWorks because it was 'more engineery' than CE (did I mention the company failed?)

All of the statements poopooing Windows CE so far are based on ignorance and hyperbole. Please spare me the indignity of posting links to Wikipedia. You know how to get there without help.

[dr.diesel]

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? 

Do you want to use the USB or LAN connectivity in corp environments?  Meaning either connecting a USB flash or USB data cable to another PC or via LAN?

Many people use these data and software packages to pull info from the test equipment, which is usually done via USB or LAN.  This would be forbidden at several places I've worked because the equipment was incapable of loading antivirus.

[dr.diesel]

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.

Ha ha, you've apparently never worked for large utilities, IT is worse than HR.

[Bored@Work]

You base all of this on a sales pitch at an event some years ago?

No, it was a paid-for, multi-day developer conference, only that Microsoft decided to make it more into a multi-day propaganda event.

We went there because we used CE, and thought we did something wrong, because the results sucked so much. After the conference we were sure it wasn't us who sucked, it was CE. We continued to use CE for some more time, shipped the products we had under development and then dropped the junk like a hot potato.

[mikeselectricstuff]

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.

For a product like this, the need to use an OS is marginal - there are plenty of standalone graphics libraries, the UI is just buttons. USB functionality is very limited, and filesystem is not a huge deal either.
If you were just designing this product in isolation, then using any 3rd party OS could probably be avoided with similar development effort to learning and adapting one.
However for a company like Agilent, they need something that's useable on a wide range of architectures, including products that really need a complex OS.
If the OS was designed in a way that allowed it too be easily stripped down to only what was needed for a particular application it wouldn't be an issue -  what does the DMM OS actually _need_ to do at startup? Almost nothing - just some selftests.
I'm convinced that the bulk of boot time in OSs like this is nothing but lazy programming - inappropriate timeouts, trying to talk to hardware that isn't there, decompressing code that's never needed, not threading things like network initialisation properly etc.
It would certainly be possible to write an OS for this sort of application with negligible boot time.
The problem is how many people consider startup time a sufficient issue to be a major selling point? Unfortunately very few, so there is no incentive to invest in improving things.
This is a problem with the majority of embedded systems - many modern LCD TVs take longer to turn on than the old CRT ones.

BTW I hear on good authority that the priority for this product was getting something out the door that worked properly, and there is a new firmware version in the works which is likely to approximately halve the  startup time. 

However annoying boot time is, Software development time is always finite, and  given the choice between slow boot and flakiness in operation, the former is the least-worst option.

[John Coloccia]

Windows CE has been rock solid for 15 years.  The development environment is light years ahead of everyone else...Visual Studio is in it's own league and really has no competition.  Unix/Linux environments are much as they were 20 years ago...and 30 years ago...and 40 years ago.  It's like playing with tinker toys.  The threading model and libraries for Windows are more advanced and more usable than anything you'll find elsewhere.  Basically, it's a programmer's paradise if you approach it with an open mind.

Assuming you're going to use an OS at all, WinCE is the slam dunk, obvious first choice for a device like this, and by a wide margin.  Someone else mentioned cost.  I believe Core still costs <$5 per device.  It's not like I'm even a fan of Microsoft or Windows, but we're not talking about desktop environments.  It's about selecting the right tool for the right job.

[dr.diesel]

The problem is how many people consider startup time a sufficient issue to be a major selling point? Unfortunately very few, so there is no incentive to invest in improving things.

Good point.

Turn it on in the morning, off at night - if you remember.

[dr.diesel]

The threading model and libraries for Windows are more advanced and more usable than anything you'll find elsewhere.

Ha ha, tell that to the guys at top500.org.

[Stonent]

There's an air leak test device I saw before that pressurizes the system and does a leak down check and it runs an old version of Windows CE also, but it's pretty much completely non-interactive, no touch support. It just has a 10 digit keypad and some start and stop test buttons. They've got their test dialed in and doubt if they change it ever.

No need to reinvent the wheel. Once you get the kernel booting and something on the screen, you just get yourself a regular windows programmer to write the code.

[John Coloccia]

The threading model and libraries for Windows are more advanced and more usable than anything you'll find elsewhere.

Ha ha, tell that to the guys at top500.org.

Ha!  OK, maybe that statement needed to be qualified a bit 

[jzoeller]

The only thing keeping me from buying this meter is the lack of capacitance measurement.

[Christe4nM]

Well, IMO a decent LCR meter does capacitance more accurate anyway. So if you're after capacitance, why not go for both the 34461a and a U1700 series for example. Together the price point comes closer to the 34410a or 34411a, but now you have a good LCR meter too. Also there are good alternatives to the U1700's that are cheaper as well. Just browse the forum for examples.

[FrankBuss]

If the OS was designed in a way that allowed it too be easily stripped down to only what was needed for a particular application it wouldn't be an issue -  what does the DMM OS actually _need_ to do at startup? Almost nothing - just some selftests.
I'm convinced that the bulk of boot time in OSs like this is nothing but lazy programming - inappropriate timeouts, trying to talk to hardware that isn't there, decompressing code that's never needed, not threading things like network initialisation properly etc.
It would certainly be possible to write an OS for this sort of application with negligible boot time.

WindowCE has a good "platform builder" software, where you can select which components you want in the image. No need for USB or Internet Explorer? Just deselect it. Makes the image smaller and the boot time faster.

Linux has a similar system, Buildroot: http://buildroot.uclibc.org

I've worked with both and there is no best system, both have their pros and cons, depending on the product and on other factors, as written here before by others, like how fast you have to build program the firmware (writing a .NET application with USB support for thumb drives can be much easier than trying to implement your own USB host controller firmware without an OS), is there a BSP already available for it, do you have engineers who already know Linux/Windows programming etc.

[fpga]

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

     , couldn't agree more.

How about a retro project with rotary switches and good old moving coil meters! If we want to go digital, we could use Nixie tubes! GUIs are for sissies!

Seriously, that could be a fun project. Make a retro front panel, complete with plywood, that controls a modern instrument over USB or LXI!

[fpga]

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.

I've experienced situations where a networked scope in a lab running Win98 had launched an inside attack on a corporate network. The IT department had to shut down all of the servers, check every desktop PC, and the last place they looked or suspected was a piece of test equipment in the lab. Nobody even thought about putting anti-virus software on a scope.

The WinCE based devices boot a fixed image from flash each time they are powered up. In the very unlikely event that they could get infected with a virus, all you would need to do is power cycle them to clear it.

[duskglow]

Running Windows CE on a piece of test equipment is defensible.  Running Windows 98?  Whoever made THAT decision needs to never work in the industry again...  That's like trying to run Commodore BASIC on a Cray.

[fpga]

Running Windows CE on a piece of test equipment is defensible.  Running Windows 98?  Whoever made THAT decision needs to never work in the industry again...  That's like trying to run Commodore BASIC on a Cray.

Most of the high end test equipment has a life of 10 to 20 years, particularly if it cost over $100k when new. Back in 2006 when I witnessed the event, that scope was still being used daily.

[duskglow]

My point is, that even when Windows 98 came out, it was a buggy piece of crap that no one in their right mind would have used for mission critical embedded applications.  Windows NT existed at around the same time, that would have been a much better choice, though probably way more expensive.

[FrankBuss]

How about a retro project with rotary switches and good old moving coil meters! If we want to go digital, we could use Nixie tubes! GUIs are for sissies!

Actually once I implemented a moving coil meter on a 7" TFT (for audio measurement), because the customer wanted the look and feel of the old instruments. Simulating a realistic needle movement for really old school VU meters was not easy, but marketing loved it

The WinCE based devices boot a fixed image from flash each time they are powered up. In the very unlikely event that they could get infected with a virus, all you would need to do is power cycle them to clear it.

Not in the Agilent DSO-X 3000 series scopes. They mount a partition at boot time where the scope software is installed. But the OS system programs and DLLs are still in the read-only image, so maybe unlikely that a virus infects the custom DLL and EXE files.

[dr.diesel]

The WinCE based devices boot a fixed image from flash each time they are powered up. In the very unlikely event that they could get infected with a virus, all you would need to do is power cycle them to clear it.

Very true, but big corporate IT morons are very static and don't listen to reason.     In cases like these, they'd never know anyhow, but it would be your ass if some one in a billion event happened and it caused trouble.  Out would come their 500 page IT policy and you'd be a gonner!

I've also worked were to receive LAN permission you had to submit a document, include the OS, what antivirus and list of all loaded patches! 

[fpga]

Very true, but big corporate IT morons are very static and don't listen to reason.     In cases like these, they'd never know anyhow, but it would be your ass if some one in a billion event happened and it caused trouble.  Out would come their 500 page IT policy and you'd be a gonner!

I've also worked were to receive LAN permission you had to submit a document, include the OS, what antivirus and list of all loaded patches!

I once worked for a European company that locked down the LAN to authorized MAC addresses in addition to VPN and domains. You would be automatically logged off after 15 minutes of non-use.

That same company required a 5 page approval form signed by your manager, the director, and the company CEO before they let you plug a desk lamp to a wall power outlet. You needed to make sure the lamp had all of the appropriate CE certificates, proof of proper training on its use, estimate its annual power usage, describe why it was necessary, steps you would take to minimize its use, responsibility of failure, responsibility of liability, and so on. Plugging in a phone charger was considered theft that would mandate disciplinary action and could result in dismissal. Luckily a coworker warned me before the manager could find out.

[duskglow]

Wow.  That would cost more money to take the time to fill out and approve the form than it would to power the lamp for a year.

[c4757p]

... lamp ... proof of proper training on its use

 

How do people get to be in charge of making these rules? By banging their heads really hard on a wall like this? Whoever lasts the longest wins?

Jesus Christ, I wonder if anybody ever thought to compare the money they save by making sure everything is done "properly" (and considering use of a phone charger "theft") with the money it costs to maintain all these layers of idiocy.

It's not even like Dilbert, it's like a parody of Dilbert. That's sad.

[fpga]

It's not even like Dilbert, it's like a parody of Dilbert. That's sad.

The thought of being dragged on the carpet in front of these people is even worse!

[mike_kawasaki]

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.

Dave, you are spot-on with your answer.

At Agilent we have standard platforms for different levels of test equipment (in laymen terms -- basic, mid-range and high-performance).  The 34460A uses the basic platform.  The platforms are chosen by a central Technology Leadership Organization in partnership with the Divisions.  The Technology Group standardizes on all the design choices to greatly simplify the product design engineer's job -- and so they can focus on the acquisition and display HW/SW design.

These decisions have become even more important as the Test Equipment value resides more in the software applications.  Standard platforms allow us to leverage the software design.  For instance, we just introduced the Real-time Spectrum Analyzer on our MXA model, just months after announcing it first on the PXA model.  In years past this would have taken at least a year to write the same code for a different platform.

I can't remember when the Basic Platform design was last updated, but it has been years since the decision to use WindowsCE.  As also mentioned in a few entries, Test Equipment is often used for >10 years, so the platform decisions require a balance between cost, design tools, functionality and vendor support.

As always, impressed with this group's knowledge and passion for Design Decisions!!

Mike

[mikeselectricstuff]

... lamp ... proof of proper training on its use

 

How do people get to be in charge of making these rules? By banging their heads really hard on a wall like this? Whoever lasts the longest wins?

The problem is as soon as you put someone in charge of this sort of thing, they have to justify their existence and be seen to be doing something. Just like politicians, there are never enough rules/laws - if someone decided everything was OK they'd be out of a job.

[c4757p]

Whining that your multimeter has WinCE is like whining that the capacitors in your television have black plastic labels. "But I don't like black! They should be blue!" Who gives a damn, they work and you don't see them! Jesus, I've heard of wine snobs, but embedded OS snobs? Piss off...

Meant in the nicest of ways, of course.

[c4757p]

The problem is as soon as you put someone in charge of this sort of thing, they have to justify their existence and be seen to be doing something. Just like politicians, there are never enough rules/laws - if someone decided everything was OK they'd be out of a job.

Not necessarily true, though, or rule books would just be piling up everywhere around the world with the right way to lick an ice cream cone and which side of your head to part your hair on. Obviously it happens in some places, but most places aren't quite that draconian. There's definitely something more authoritarian and legalistic in some companies' cultures than in others.

[fpga]

The problem is as soon as you put someone in charge of this sort of thing, they have to justify their existence and be seen to be doing something. Just like politicians, there are never enough rules/laws - if someone decided everything was OK they'd be out of a job.

We strayed way off topic on this thread. I just hope you don't have policies or people like that where you work.

[jancumps]

Whining that your multimeter has WinCE is like whining that the capacitors in your television have black plastic labels. "But I don't like black! They should be blue!" ...

Wow, you worried me there for a moment. I had to check this:

[mikeselectricstuff]

The problem is as soon as you put someone in charge of this sort of thing, they have to justify their existence and be seen to be doing something. Just like politicians, there are never enough rules/laws - if someone decided everything was OK they'd be out of a job.

Not necessarily true, though, or rule books would just be piling up everywhere around the world with the right way to lick an ice cream cone and which side of your head to part your hair on.

You're not familiar with the EU then... they seem to do little else.

[ChadSeibert]

The problem is as soon as you put someone in charge of this sort of thing, they have to justify their existence and be seen to be doing something. Just like politicians, there are never enough rules/laws - if someone decided everything was OK they'd be out of a job.

Not necessarily true, though, or rule books would just be piling up everywhere around the world with the right way to lick an ice cream cone and which side of your head to part your hair on.

You're not familiar with the EU then... they seem to do little else.

Eh, there's always quibbling over existing laws. No need to argue about ice cream cones when you can just argue about the same thing over and over. 

[ejeffrey]

Ha ha, you've apparently never worked for large utilities, IT is worse than HR.

No, although I have worked for a large company.  Also I know that it is impossible for most companies that require non-trivial technology to avoid windows, at least if you count windows CE.  This meter is the tip of the iceberg.  I don't think you can even buy an oscilloscope that doesn't run some version of windows any more.  If the IT department tells the CTO that you can't use your $500,000 65 GHz oscilloscope, or your $10M photolithography system, or whatever, you know what happens?  The IT guy gets fired.

Seriously, these companies have the ability to set up private networks for running special purpose equipment.  If a regular person asks, they lie and say no because it is less work and gives them a power trip.  Once someone important finds out that they are impeding actually doing work, the solutions magically come out of the woodwork.

[SeanB]

At work I plug in my laptop, and have no problems with it, as all I am doing it for is to use a network printer direct. not going to connect to the Windows server just to print, so CUPS just works direct a lot faster. As well I am remote control for the IT provider, I often get a call to go and change tapes for the off site backup, as they either need to reinsert or the regular driver ( Jay) is running late, so I go and change tapes and leave them for him to collect the next day. Simple as there are 4 days of tapes there for use, just in case. The backups go off site, along with a hard drive kept elsewhere.

If somebody had to bring up the rule of not plugging in a phone charger probably most of the staff would be on strike the first day. All good and well, but if you do not actually have electricity at home and have a cellphone.......

[dr.diesel]

I don't think you can even buy an oscilloscope that doesn't run some version of windows any more.

Sure you can:

https://www.eevblog.com/forum/testgear/equipment-running-windoze/

The $500,000 65Ghz Scope is running a full blown version, you could load antivirus if you wanted - although not condoned I'm sure. 

But your correct, for that kind of money you could get the right people involved, but for $1000 meter, they'd tell you to piss off, especially when there are plenty of other alternatives.

[ejeffrey]

But your correct, for that kind of money you could get the right people involved, but for $1000 meter, they'd tell you to piss off, especially when there are plenty of other alternatives.

The point is, any company that has a significant investment in special purpose hardware has had to solve this problem already.  If you are one guy working on hardware in the corner at a large company that mostly just pushes paper around or does software development, then yes you have a problem, and not just for this meter.  If you work in an actual lab environment, this isn't a problem because it has already been solved.

Also, in my experience, if they won't let you connect something running WinCE to the network, they won't let you connect *anything* to the network except for desktop PCs and networked printers specifically purchased by the IT department.

[Alexei.Polkhanov]

Windows CE has been rock solid for 15 years.  The development environment is light years ahead of everyone else...Visual Studio is in it's own league and really has no competition.  Unix/Linux environments are much as they were 20 years ago...and 30 years ago...and 40 years ago.  It's like playing with tinker toys.  The threading model and libraries for Windows are more advanced and more usable than anything you'll find elsewhere.  Basically, it's a programmer's paradise if you approach it with an open mind.

Assuming you're going to use an OS at all, WinCE is the slam dunk, obvious first choice for a device like this, and by a wide margin.  Someone else mentioned cost.  I believe Core still costs <$5 per device.  It's not like I'm even a fan of Microsoft or Windows, but we're not talking about desktop environments.  It's about selecting the right tool for the right job.

Visual Studio is very good dev environment, I still consider it a nice 'editor' more than anything else and I would jump of it into WinDbg to debug. Choice of dev environment is purely personal preference. I may argue that when I use Emacs and compile on command line things seem to go faster. 

With regards to threading and other useful features (as in useful for EMBEDDED OS) I would strongly disagree. CE maybe somewhere between VxWorks and QNX since Windows CE has advantages for embedded UI apps, VxWorks is definitely better when code size, performance and hard real-time matters, followed by RTLinux which is free but has larger footprint, QNX has sexy, compact UI framework. Someone who used pSOS and other embedded OS probably will challenge my opinion here and they maybe right. For example Mars Pathfinder is running VxWorks, Cisco replaced (RT)Linux by VxWorks in WRT routers and saved money on memory even if VxWorks is not free.

Perhaps where CE has really failed them is longer than necessary boot times. I would say that anything more than 4 seconds is unacceptably long - this is just a fronted for DMM, not a space station. I have seen entire Ubuntu Linux booting faster on PC with flash drive!

[jancumps]

This thread now fully complies with the rule that if someone mentions an ide, someone else mentions vi or emacs. 

[SeanB]

Actually you really should not have to boot, if your hardware is fixed ( in a meter definitely) just have an image decompressed to ram on startup that is already running, in the init code you set up registers and such with boot code, uncompress image to ram, set all pointers and stack to a preset frozen state then the bootloader kills itself by jumping into an entry point, when the main starts running as if it never stopped from the initial state, and then sees the bootloader as free memory. Can be done in under 1s if you do proper image and compress it into rom and use a simple bootloader. If you want to do firmware updates have a simple link looked at by the bootloader code during startup which jumps to look for the new firmware and checksums it then writes it to flash then gives a message pass or fail and halts the processor. Reboot without the jumper and away you go..

[John Coloccia]

I like VxWorks.  I've used it and it's generally a nice environment to work in.  I certainly trust it for critical applications more than WindowsCE, and I suspect that's why you see it used frequently in space, military vehicles, etc.  It's missing some really great thread features that you find in Windows, though (it's generally Posix compliant).  For example, some of the most powerful features Windows brings to the table are things like Events, WaitForMultipleObjects(), and things like that.  Semaphores and Mutexes are nice, but the way windows handles thread synchronization is a thing of beauty.

But if it's going to run my life support system, VxWorks isn't a bad choice over Windows!.  I've used pSOS too.  Nothing really remarkable other than it's teeny tiny.  I guess Wind River bought it and subsequently killed it.  Didn't they do the same to RTLinux too?

[rsjsouza]

Actually you really should not have to boot, if your hardware is fixed ( in a meter definitely)

I don't disagree with your statement above at all, but in practice what I usually see in the OSes I worked with is they don't get it completely right. Over time a great number of suspend/resume switching ends up in unknown states or unexpected behaviour (peripherals don't get properly restored to their pre-suspend settings, external devices don't get properly configured, etc.). In this case the equipment manufacturer tends to go the safer way and simply restores the system to a known-good full reset configuration (apart from some minimal settings before turn off).

I also think the manufacturer does not spend too much resources in optimizing boot times for a bench equipment - from a marketing perspective this is not as significant as in a portable device.

[SeanB]

True, but as you know the hardware you set all the registers and other hardware registers on startup and force load them. Not going to take more than 1000 instructions to just write all the registers, less than 50mS to do it all at each reset whether from power on or soft reset. Not a probe, look up in table, decide on action and wait for timeouts from hardware to respond, just push it out to known stuff and boom you are ready to resume from an image ready to run.

[Alexei.Polkhanov]

Windows brings to the table are things like Events, WaitForMultipleObjects(), and things like that.  Semaphores and Mutexes are nice, but the way windows handles thread synchronization is a thing of beauty.

I see where you going, yes you absolutely right - WFMO is much more efficient than select() because you don't have to iterate over all handles to find one that triggered. I have been tracking this problem since 2001. I never had to solve it for embedded platforms, but for large servers on *NIX (like Linux) problem was known as C10K problem (http://www.kegel.com/c10k.html) because waiting on 10,000 sockets with select() is not very efficient. Back then in 2000 there were already several solutions like kqueue, then we got libevent, epoll etc. You can configure you kernel to use these or to enable them as option when you configure kernel for your platform. Problem is that you have to be aware of these options, pros and cons and so on. RTLinux kernel is not same as Linux. I have not heard any sell pitches for CE, but I can guess where they would try to attack RTLinux for example.

I think Linux kernel will always be ahead of any other OS in terms of features and supported platforms because it is available for everyone to change, and so every university and every developer can add/change whatever they want. And that is what they do. Latest experimental algorithms in OS design mostly come to Linux first, but because there are no single company behind it it is up to developers/users to discover and use them.

[John Coloccia]

I really thought RTLinux had kind of died with a whimper.  I should give it another look.  I didn't realize that it was still being actively maintained.  I guess I assumed that after Wind River gave up on it that it just became sort of an artifact of a more exciting time....the late 90's....LOL.

Oh, how fast things change around here

[Alexei.Polkhanov]

I really thought RTLinux had kind of died with a whimper.  I should give it another look.  I didn't realize that it was still being actively maintained.  I guess I assumed that after Wind River gave up on it that it just became sort of an artifact of a more exciting time....the late 90's....LOL.

Oh, how fast things change around here

Sorry for confusion I almost forgot about Wind River, what I was referring to by RTLinux is Real Time Linux, which is a Linux kernel with PREEMPT_RT patch. I think RedHat is maintaining it.  Whatever was done specifically for RTLinux now ended up in many other "Embedded Linux" distros.

Situation with Embedded Linux in general is very confusing. You can get lost in names and distros and never find your way out :-) For example I have Nokia phone, N900, that runs Maemo OS, then there was "MeeGo" which is a basis of current project called "Sailfish" developed by Jolla - company that was started by people ejected from Nokia after it signed its deal with Microsoft. Debian and Ubuntu have distros targeted for embedded/mobile as well.

Just look at list of Linux OS supported by Nios II (Soft core running on Altera FPGA):
...
Linux   Nios II   Timesys
Linux   Nios II   Wind River
Linux   Nios II   SLS
Linux   Nios II   CodeSourcery
Linux   Nios II   Open Source Community
...
µCLinux   Nios II   SLS
µCLinux   Nios II   Open Source Community
...

It seems that everyone has its own flavor of embedded Linux. It is a little bit of a Embedded Linux zoo.

[lewis]

Dave - When's the review coming? Looking forward to that one...

[EEVblog]

Dave - When's the review coming? Looking forward to that one...

It has been mostly shot. Just need a final few minutes of material and a summary.
It's already an hour long 
I'm going to have to leave out any PC based playing around for brevity.
So should be #489

[John Coloccia]

Windows brings to the table are things like Events, WaitForMultipleObjects(), and things like that.  Semaphores and Mutexes are nice, but the way windows handles thread synchronization is a thing of beauty.

I see where you going, yes you absolutely right - WFMO is much more efficient than select() because you don't have to iterate over all handles to find one that triggered. I have been tracking this problem since 2001. I never had to solve it for embedded platforms, but for large servers on *NIX (like Linux) problem was known as C10K problem (http://www.kegel.com/c10k.html) because waiting on 10,000 sockets with select() is not very efficient. Back then in 2000 there were already several solutions like kqueue, then we got libevent, epoll etc. You can configure you kernel to use these or to enable them as option when you configure kernel for your platform. Problem is that you have to be aware of these options, pros and cons and so on. RTLinux kernel is not same as Linux. I have not heard any sell pitches for CE, but I can guess where they would try to attack RTLinux for example.

I think Linux kernel will always be ahead of any other OS in terms of features and supported platforms because it is available for everyone to change, and so every university and every developer can add/change whatever they want. And that is what they do. Latest experimental algorithms in OS design mostly come to Linux first, but because there are no single company behind it it is up to developers/users to discover and use them.

At one point, I wrote a little library using posix semaphores and mutexes that simulated the way Windows handled events and things like that, and it was pretty efficient.  This was many years ago.  I forget the details of exactly what I did, but I think it was something along the lines of launching threads to wait on individual synch objects to get signaled, and then each caller actually waited on a different object that sort of signaled when something in their list was ready.  I guess it really ended up being kind of a thread synchronization mini-kernel that simulated what Windows was doing.

I think it's long gone, but I have some old stuff kicking around here.  If I happen to find it, and I think it's useful, I'll maybe post it here or start another thread on it somewhere else.

[lewis]

Dave - When's the review coming? Looking forward to that one...

It has been mostly shot. Just need a final few minutes of material and a summary.
It's already an hour long 
I'm going to have to leave out any PC based playing around for brevity.
So should be #489

Awesome. The longer the better!

[CChin254]

Here is the IC Identification of this device. The PDF (in the next post) has the cost distributions for the manufacturers and some other stuff.

[CChin254]

PDF (Sorry, too large to fit in previous post)

Unfortunately, there is an error on page 9 that Linear Technology should have been Analog Devices. Sorry.