Many (most?) meters at this price don't support firmware updates at all.
I would like to thank everyone for the valuable feedback. I was under the impression that resistance measurement was recently improved to around 4.2-4.5 seconds.
The range switch reliability is something which i haven't thought about and is a valid point: No matter how feature-full and accurate, how are you going to use your device if you can't turn it on ?
The above is an extreme example of course, but the idea of joeqsmith (mechanical stress) is well worth taking into consideration.
@exe Personally, I do not believe in objective, non-polarized opinions of people, which is why i'm interested in everyone's opinion. Polarization is the reason that i've chosen this thread to post in.
Again, Thank you !
Many (most?) meters at this price don't support firmware updates at all.
Because they don't need it?
"Just to be clear, I bricked it with own firmware, not with the stock one."
You can't play with it so much , it is complicated to reverse engineear the code and maybe doesn't worth the pain ... so it is not hackable , just in theory .
I'm aware only for that "Hello World" on display , that is not difficult to create if you find in code the text "U-1.57" - the current software version displayed at start-up . You can replace it with everything ... your name maybe . But to reverse engineer all , without the source code and to understand it , is much harder than to write your own code from scratch . A decompiler will give you something , but is not the original code , much must be interpreted and are many ways . That's why it is useless .
We understand your point of view ... your hobby testing how robust a meter is . As a user you dont care that much if the switch won't last only 20K cycles in the future ... but the firmware is buggy now and you can't use it as you would like .I would be pissed if I paid 300+ for a meter and the switch went bad in the first year or two. The UNI-T was only $30 and really what I expect from a cheap meter with nominal use. Same for BK and Mastech. I consider them disposable. But at $300 it better be built to stand the test of time.
Same holds true for basic transients. Last thing I want is a meter like my first brand new Fluke. Look at it wrong and a $70+ dollar repair bill, that was in the 80s. Firmware can be fixed but if the hardware is wrong, there is little you are going to do to correct it.
My normal use of a handheld meter is pretty basic. That's why I buy cheap, disposable meters for the garage. The 121GW would be out of place in that environment.
For potential buyers is important to know the switch longevity , but users can't do anything as you said ( besides beeing pissed )
So we concentrate on what can be changed , the firmware .
And without a mature firmware many switches will last for ever , who would use daily such a multimeter ?
I don't remember the exact count for our testing of the switch but I believe it was 40000. We did our range switch testing live on youtube.
Yea, I know Dave ran what he called his 50,000 cycle test on it, I watched.
No, he increased the autorange speed, Dave did a video about it, too:
...
He has published everything in Github:
...
But you are right, probably not useful as the base for a fully open source version. But the circuit diagram is open source, so someone could develop a cleanroom implementation of an open source firmware for it. Shouldn't be too difficult, just a lot of work for all the functions the original firmware has.
Every multimeter has the advertised number of counts 4000 , 6000 , 50000 all the time and switches up and down above this value , lets say at 4400-4100 , 6600-6300 , 55000-52000 ...
Pretty bad , I hope you don't want 121GW to copy the exceptions or slow meters with the hardware that it has ...
If the hysteresis is very big will eat some resolution because for a 50.000 count meter you can't use a giant up level like 65.000 just to have down level above 50.000 count .
I think I don't have to explain again that if you adjust a voltage up and down you will experience this loss of resolution .
Anyway the switching should be as seamless as possible , not this huge hysteresis and slowness that now the firmware has ... I don't think any user would want different or wouldn't care
[...] to copy the exceptions [...]
The big step in my opinion would be to make a firmware capable of "normal" autorange hysteresis in all modes - volts , amps , resistance and so on.
Every multimeter has the advertised number of counts 4000 , 6000 , 50000 all the time and switches up and down above this value , lets say at 4400-4100 , 6600-6300 , 55000-52000 ...
Hmm , almost all , if not all , multimeters with the microcontroller imbedded with the measurement chipset , old and new , even the cheapest chinese ones .
Hmm , almost all , if not all , multimeters with the microcontroller imbedded with the measurement chipset , old and new , even the cheapest chinese ones . And the fast multimeters with separate microcontroller ... the extreme hysteresis that needs to go below the nominal counts is a clear indication for slow autoranging .
Metrix 3293, 10.0000 scale : going up at 9.9999, down at 09.900
Metrix 3293, 10.0000 scale : going up at 9.9999, down at 09.900
And the price?
Metrix 3293, 10.0000 scale : going up at 9.9999, down at 09.900