Products > Test Equipment
EEVBlog 121GW Multimeter Firmware Details
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EEVblog:

--- Quote from: 1anX on December 08, 2018, 04:29:39 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.

--- End quote ---

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

--- Quote from: EEVblog 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.

--- End quote ---

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 :)
exe:

--- Quote from: joeqsmith on December 07, 2018, 02:13:56 pm ---
--- Quote from: exe on December 06, 2018, 02:57:56 pm ---
--- Quote from: joeqsmith on December 05, 2018, 12:46:26 pm ---If anyone has bricked one from upgrading the firmware, chime in.

--- End quote ---

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.

--- End quote ---

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.

--- End quote ---

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.
EEVblog:

--- Quote from: exe on December 08, 2018, 11:40:32 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.

--- End quote ---

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

--- Quote from: joeqsmith on December 08, 2018, 11:11:17 am ---
--- Quote from: 1anX on December 08, 2018, 03:31:43 am ---
--- Quote from: EEVblog 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.

--- End quote ---

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.

--- End quote ---

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?

--- End quote ---

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 ) 
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