Author Topic: EEVBlog 121GW Multimeter Firmware Details  (Read 69917 times)

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Offline Terry01

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #200 on: December 07, 2018, 04:42:20 pm »

Cool, thanks for the information. I would never have guessed that as there is no indication on the meter around the jacks and I haven't read the manual.

There is a indication, the A terminal is marked "A 500mA", because it is both ampere and 500mA range.

I agree that 500mA is clearly marked on the A jack but can't see how that would indicate the mA jack is only good for 55mA.
I also see no one else has told me that and I have made a couple of posts about trying to feed 90mA into the mA jack so it can't be that obvious or well know or someone else would have said.
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Offline darik

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #201 on: December 07, 2018, 05:56:00 pm »

Cool, thanks for the information. I would never have guessed that as there is no indication on the meter around the jacks and I haven't read the manual.

There is a indication, the A terminal is marked "A 500mA", because it is both ampere and 500mA range.

I agree that 500mA is clearly marked on the A jack but can't see how that would indicate the mA jack is only good for 55mA.
I also see no one else has told me that and I have made a couple of posts about trying to feed 90mA into the mA jack so it can't be that obvious or well know or someone else would have said.

The "OFL" that the meter displayed means exactly that you have exceeded the current limit in the selected range. What else could OFL mean in an amps setting? That was a good indication, but you incorrectly assumed the meter was lying to you.
 

Offline Terry01

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #202 on: December 07, 2018, 06:14:02 pm »

Cool, thanks for the information. I would never have guessed that as there is no indication on the meter around the jacks and I haven't read the manual.

There is a indication, the A terminal is marked "A 500mA", because it is both ampere and 500mA range.

I agree that 500mA is clearly marked on the A jack but can't see how that would indicate the mA jack is only good for 55mA.
I also see no one else has told me that and I have made a couple of posts about trying to feed 90mA into the mA jack so it can't be that obvious or well know or someone else would have said.

The "OFL" that the meter displayed means exactly that you have exceeded the current limit in the selected range. What else could OFL mean in an amps setting? That was a good indication, but you incorrectly assumed the meter was lying to you.

Yes I agree. I incorrectly assumed the meter was lying to me but lets be clear the meter is hardly 100% trust worthy is it? There are loads of posts of the meter lying or not doing what it's supposed to or whatever. I can hardly be faulted for thinking it was just something else wrong with it.
I have a few other meters that are not limited to 55mA in the mA range and I haven't read the manual for the 121GW. Like I say too, I posted a couple other times about this problem and no one else knew this so if it was that obvious someone else would have knew and told me.

You think it's obvious, I don't. I can't see how "OFL" would translate into "55mA is the max this jack will read"
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Offline Terry01

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #203 on: December 07, 2018, 06:59:26 pm »
I will read the manual for this meter next time I have a while to take it in for sure. I have MS and sometimes I need to read the same thing 3 or 4 times for it to register. Things like user manuals and the likes I read on days where I feel like my memory will co-operate with me.
The meter has a few nice features for sure. 1 of the other things I got caught out with was, I put fresh lithium in it when I got it and another forum member pointed out to me the little bit extra voltage "fresh" lithium have is enough to affect the diode and resistance mode so it's not a good idea.
Something else that is probably clearly stated somewhere and I never read it or whatever but I would say is not obvious too.

Something that is obvious..... I need to RTFM!!  :o

My lack of knowledge probably plays a huge part too but hey ho!
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Offline HKJ

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #204 on: December 07, 2018, 07:10:03 pm »
Yes I agree. I incorrectly assumed the meter was lying to me but lets be clear the meter is hardly 100% trust worthy is it? There are loads of posts of the meter lying or not doing what it's supposed to or whatever. I can hardly be faulted for thinking it was just something else wrong with it.

I have not seen that, in some extreme cases the meter shows wrong values, in normal usage it may be slow or it may be unstable, but it do not show wrong values.
This is something you have to know about every meter you use, where is it correct and stable, where may it show wrong value and where is it wrong most of the time. I do not remember it for all my meters, but if the value is outside expected values I check with another (or more, even a scope) meter.
 

Offline gdewitte

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #205 on: December 07, 2018, 07:24:06 pm »
It's clearly (at least to me) stated in the manual.  … 


Where in the manual is it clearly stated? I just searched the latest manual (revised 04 Dec. 2018) for things like "55" and "current" and had no returns relating to a 55 mA maximum.
 

Offline darik

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #206 on: December 07, 2018, 07:30:55 pm »
It's clearly (at least to me) stated in the manual.  … 


Where in the manual is it clearly stated? I just searched the latest manual (revised 04 Dec. 2018) for things like "55" and "current" and had no returns relating to a 55 mA maximum.

In the version 1.22 manual I have on my drive it states it on page 16, where it details the current ranges, and on page 32, where it details the different jacks.

And of course since taking current measurements that are out of range is one of the easiest ways to damage a meter or at least blow a fuse, we _all_ familiarize ourselves with the limitations of the current ranges before using them. Right?
 

Offline HKJ

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #207 on: December 07, 2018, 07:40:53 pm »
Yes I agree. I incorrectly assumed the meter was lying to me but lets be clear the meter is hardly 100% trust worthy is it? There are loads of posts of the meter lying or not doing what it's supposed to or whatever. I can hardly be faulted for thinking it was just something else wrong with it.

I have not seen that, in some extreme cases the meter shows wrong values, in normal usage it may be slow or it may be unstable, but it do not show wrong values.
This is something you have to know about every meter you use, where is it correct and stable, where may it show wrong value and where is it wrong most of the time. I do not remember it for all my meters, but if the value is outside expected values I check with another (or more, even a scope) meter.

You say it shows wrong values then it doesn't show wrong values in the same sentence. You say it is slow  or unstable... this is not wrong values??

I did check it with another meter, 2 in fact U1273a and 87v.

next.....  :horse:  :horse:  :horse:  :horse:

It may show wrong value at high megaohms. In current it may have a zero offset (As I note in my review), this is not ideal, but easy to handle. The low burden voltage has a price.
In some ranges the auto range do not work, this is easy to fix: Use manual range.

The meter is not perfect, but I do not see it as unreliable. I hope it will get better with some software updates, making it easier to use in all situations.

Note: For me a unreliable meter is a meter where you cannot see that it is showing a wrong value (when you are within specifications).
 

Offline HKJ

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #208 on: December 07, 2018, 09:01:51 pm »
On this we agree  :)

Just to clarify (Others can add more points):
  • Offset do not make a meter unreliable, but is inconvenient, even if the meter has a REL function.
  • Measuring frequencies (including harmonic) outside the specifications  is not expected to show correct values, but high sensitivity for specific frequencies may rate as slightly unreliable. Like changing reading when a mobile phone is near the meter (I would rate it as silly to measure with high RF fields around).
  • Auto range jumping around, this is a software fault in the meter, but do not make it unreliable.
  • Problems with mixed AC+DC signals. I do not really now how to rate this, as long as they are of similar amplitude I expect the meter to handle it, but when there is a huge difference most meters will be unreliable.
  • Sensitive to hands near the meter, this is easy to see and do not make the meter unreliable, but is very inconvenient

As can be seen from the list, there is a lot of stuff I do not like, but I would not call the meter unreliable due to it.

The 121GW is not my main meter and will probably never be, it is too slow. But is has some functions that I like and this means I keep it within easy reach and do use it.
 

Offline HKJ

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #209 on: December 07, 2018, 09:56:59 pm »
I like to use all my meters.

I have way to many meters for that, I have a few hand held meters I use for checking stuff (That includes the 121GW) and some bench meters I use when I want precise result (Keithley, Fluke  and Keysight).
 

Offline CDaniel

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #210 on: December 07, 2018, 10:23:05 pm »
Unreliable is just a word , at the end of the day the firmware is at least very "unfinished" after 1 year in production ...
Even the sensitivity to noise could be just software related ...

« Last Edit: December 07, 2018, 10:25:10 pm by CDaniel »
 

Offline HKJ

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #211 on: December 07, 2018, 10:36:20 pm »
Unreliable is just a word , at the end of the day the firmware is at least very "unfinished" after 1 year in production ...
Even the sensitivity to noise could be just software related ...

It is not just a word, a long time ago I bought a fairly fancy multimeter. When I got it the mains was maybe 10V (I do not remember the exact values) and other voltage readings was also very far off, I decided that it was definitely a bad meter and it had to be returned. I was (as usual) rater busy and left it alone for a couple of days, then I got around to it again, this time it was very precise.
I did not return the meter and have never used it, for me it is unreliable (And some lost money).
 

Offline CDaniel

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #212 on: December 07, 2018, 11:07:40 pm »
Ok , we will use "unreliable" only for defective meters then  ;)
« Last Edit: December 07, 2018, 11:14:09 pm by CDaniel »
 

Offline bicycleguy

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #213 on: December 08, 2018, 01:42:29 am »
...
I also see no one else has told me that and I have made a couple of posts about trying to feed 90mA into the mA jack so it can't be that obvious or well know or someone else would have said.
Thought you'd figure it out.  Didn't want to make you feel like an idiot :D 
Don't feel bad though, Iv'e done the same thing a few times but usually RTFM. |O
 

Offline EEVblog

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #214 on: December 08, 2018, 03:07:12 am »
For those interested, we (Kane & EEVblog) are now setting up a shared git (not public) for firmware version control with the intention that we (EEVblog) now have full visibility on all firmware changes, and in time will be able to make our own changes and compile ourselves etc.
At present we have almost no real visibility into their internal firmware environment.
 

Offline 1anX

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #215 on: December 08, 2018, 03:31:43 am »
For those interested, we (Kane & EEVblog) are now setting up a shared git (not public) for firmware version control with the intention that we (EEVblog) now have full visibility on all firmware changes, and in time will be able to make our own changes and compile ourselves etc.
At present we have almost no real visibility into their internal firmware environment.

Thats great news Dave!

This meter carries your name and brand, (EEVBlog) so its good that you are in the loop with the development of the firmware. It seems to me that with responsible management this meter could develop to its true potential.

The hardware too requires your input and direction toward meeting quality and performance requirements. If UEI want to carry on with 700 out of spec PCBs requiring shims then maybe they should put their brand on it. IMHO get quality into the meters that carry your branding and be prepared for a lot more sales.
 

Offline EEVblog

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #216 on: December 08, 2018, 03:36:05 am »
The hardware too requires your input and direction toward meeting quality and performance requirements. If UEI want to carry on with 700 out of spec PCBs requiring shims then maybe they should put their brand on it. IMHO get quality into the meters that carry your branding and be prepared for a lot more sales.

I've heard you a dozen times now, no need to continue to repeat it.
 

Offline 1anX

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #217 on: December 08, 2018, 04:29:39 am »
The hardware too requires your input and direction toward meeting quality and performance requirements. If UEI want to carry on with 700 out of spec PCBs requiring shims then maybe they should put their brand on it. IMHO get quality into the meters that carry your branding and be prepared for a lot more sales.

I've heard you a dozen times now, no need to continue to repeat it.

Its called customer feedback Dave!

I've never seen you shy away from voicing your opinions on products. I was suggesting something a little different in my last post and that was to separate the out of spec PCBs from the meters carrying your brand.

You have said before that UEI are engineering the meter that incorporates some of your design ideas, (good ideas) all I'm suggesting is that if you have some control in the manufacture then opt for quality. Sure they are built to a cost of around $300, but hell, how much does the PCB cost as a percentage of the bill?

I'm participating in the forum and if you dont like my suggestions thats fine, but I dont think I'm repeating myself as much as many others do around here.
 

Online Brumby

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #218 on: December 08, 2018, 05:53:26 am »
Dave's heard you, I've heard you and I'm sure there are a bucketload of other members who have heard you - so give it a rest, please!

As for the PCB's - what is the problem?  The fact that they aren't picture perfectly identical to the original?

If I could be so bold (as a person who does not own a 121GW - but has read all these threads) - from what I've read to date - IT DOESN'T MATTER!

There is a mechanical requirement in the range switch and PCB which is accomplished by one of two configurations:
 1. Thicker PCB and no shim
or
 2. Thinner PCB with a shim
Either appear to be as good as the other

 

Online Brumby

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #219 on: December 08, 2018, 06:02:41 am »
... how much does the PCB cost as a percentage of the bill?

A crapload more than a shim, that's for sure.

BUT that isn't the sole reason.

Many meters were sent out with the thinner PCB and the shim solution dealt with the problem with a user serviceable field change.  The alternative would be a complete recall - as I don't think Dave or UEI would be sending out replacement PCBs - populated, tested and calibrated!

Sending out the shim with instructions as to how to fit it was simple, inexpensive and only inconvenienced the user for the length of time it took to fit the shim.

The shim solution was found to be good enough to be used in the construction of new units out of the factory - so the engineering has been proven.


Your pedanticism is inappropriate here.  The shim solution works well.  Please .... move on.


Edit:
Dave:  If I've overstepped the mark or got something wrong, please feel free to castigate and correct me!
« Last Edit: December 08, 2018, 06:04:50 am by Brumby »
 
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Offline EEVblog

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #220 on: December 08, 2018, 08:33:14 am »
I'm participating in the forum and if you dont like my suggestions thats fine, but I dont think I'm repeating myself as much as many others do around here.

You are repeating yourself constantly, and you've ironically just done it again. I get it, please stop now.
 

Offline ggchab

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #221 on: December 08, 2018, 10:06:09 am »
For those interested, we (Kane & EEVblog) are now setting up a shared git (not public) for firmware version control with the intention that we (EEVblog) now have full visibility on all firmware changes, and in time will be able to make our own changes and compile ourselves etc.
At present we have almost no real visibility into their internal firmware environment.

My only concern was that Dave lost enthusiasm and interest in the meter because of other projects.
Very happy he has now full access to the firmware and will even compile and test his own versions :)
 

Offline exe

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #222 on: December 08, 2018, 11:40:32 am »
If anyone has bricked one from upgrading the firmware, chime in.

Uhm, it's a standard stm32 mcu, can be reprogrammed via the swd intarface using a $5 programmer (but header is not soldered). I did brick it many times and was able to restore the original firmware and bootloader. Just be sure to dump the calibration table, I lost mine during experiments.

Good to know that it can be bricked this way.  Saves me the time of checking it.    I have not looked into programming the meter and wouldn't have expected $5 would get me setup.  Could you please provide a link to the tools and programmer I would need?   Even just part numbers and the manufactures would be great.

Just to be clear, I bricked it with own firmware, not with the stock one.

Concerning stm32 programming, any generic "st-link v2" adapter will do. I have similar to this one: https://www.ebay.com/itm/ST-Link-V2-Programming-Unit-mini-STM8-STM32-Emulator-Downloader-M89-New/401088363326?hash=item5d62babb3e:rk:1:pf:0 . Also any stm32 development board will work as they have st-link interface on the board.

Software... I'm on Linux, so I use openocd and https://github.com/texane/stlink . In general, any IDE supporting stm32 should have support for st-link, so software not a problem. Just use whatever is available for your OS. Here is the list of what's available: https://www.st.com/en/development-tools/stm32-ides.html?querycriteria=productId=LN1200 . People often use Keil and Attolic TrueSTUDIO. There are trial and free versions available.
 

Offline EEVblog

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #223 on: December 09, 2018, 02:26:39 am »
Concerning stm32 programming, any generic "st-link v2" adapter will do. I have similar to this one: https://www.ebay.com/itm/ST-Link-V2-Programming-Unit-mini-STM8-STM32-Emulator-Downloader-M89-New/401088363326?hash=item5d62babb3e:rk:1:pf:0 . Also any stm32 development board will work as they have st-link interface on the board.

Just beware, I think the pinout is different, but otherwise, yes, compatible with ST-Link-V2
 

Offline CDaniel

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #224 on: December 09, 2018, 09:41:41 am »
For those interested, we (Kane & EEVblog) are now setting up a shared git (not public) for firmware version control with the intention that we (EEVblog) now have full visibility on all firmware changes, and in time will be able to make our own changes and compile ourselves etc.
At present we have almost no real visibility into their internal firmware environment.

Thats great news Dave!

This meter carries your name and brand, (EEVBlog) so its good that you are in the loop with the development of the firmware. It seems to me that with responsible management this meter could develop to its true potential.

The hardware too requires your input and direction toward meeting quality and performance requirements. If UEI want to carry on with 700 out of spec PCBs requiring shims then maybe they should put their brand on it. IMHO get quality into the meters that carry your branding and be prepared for a lot more sales.

I will tell you that the thing I have never understood when looking at the prototype is why the board thickness will matter.  The bosses that the board is mounted to are molded to the front of the case.  The mechanical loop is all on the switch side of the PCB.   (Added cutaway showing the stackup) 

We do know that the original contacts have changed a few times, even after the kickstart.  We also know the knob was loose.  I assume the shim was added to increase the contact force (which making the board thicker will not effect). 

Are they suggesting that the PCB is actually deflecting (bowed) in the area of the switch because it is so thin?   That would seem easy enough to measure.   Maybe the case changed and somehow the board is mounted differently that causes the thickness to matter.  Looking at various pictures from the kickstart, this doesn't seem to be the case.     If the board is not deflecting, then it seems more of a case design problem (case meaning the plastic parts). 

Any MEs here that care to take a crack at some measurements?

You forgot that the switch assembly is mounted on the PCB through a hole and has plastic clamps on the other side . If the PCB is thicker the switch contact spings will be pushed harder into the PCB . So now not the shim and the upper case will push the switch to make good contact , but will stay itself closer to the PCB .
And the PCB doesn't have to be thicker by the shim thickness , is much less , much of the shim thikness is for the normal space between the case and the switch ( they are not supose to be touching ) 
« Last Edit: December 09, 2018, 12:02:23 pm by CDaniel »
 


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