Products > Test Equipment
EEVBlog 121GW Multimeter Firmware Details
Iagash:
I hooked up the 121gw to my st-link and seem to be able to dump the flash.
I also tried to read out the option bytes from the cpu.
chefkoch84:
I am a backer for the 2nd batch ... and looking forward to the new toy.
I did have some look at the firmware and had it decompiled here:
https://retdec.com/decompilation/
I was surprised how easy and straightforward that was. - Of course, the code is not very readable... but in combination with know-how on the hardware, it should be possible to have some improvements.
e.g. finding the function for the buzzer should be quite doable.
I myself could not have a very detailed look yet.
p.s. - perhaps somebody finds the source for this firmware on a USB-stick in the dumpster (next to a 500k$ scope or something ;-)
If so... it would be a very nice move to upload it here...
Edit: if you wanna use the attachments: remove the ".zip" extension from the filenames and process with 7zip. (The forum does not allow bigger files... nor files ending with .7z.001 )
Iagash:
--- Quote from: Iagash on January 25, 2018, 06:23:34 pm ---I hooked up the 121gw to my st-link and seem to be able to dump the flash.
--- End quote ---
Here is the openocd config file I used to dump the data:
--- Code: ---# 121gw.cfg openocd config
source [find interface/stlink-v2.cfg]
set WORKAREASIZE 0x4000
source [find target/stm32lx_dual_bank.cfg]
# use software reset
reset_config none
init
reset halt
flash probe 0
--- End code ---
Here is how I connected the meter. I didn't use the reset line.
--- Code: --- / 1 Vcc -------- 8 3.3V \
| 2 Reset ------ NC |
121gw - + 3 TMS/SWDIO -- 4 SWDIO + ST-Link-v2 mini
CN3 | 4 TCK/SWCLK -- 2 SWCLK |
\ 5 VSS -------- 6 GND /
--- End code ---
This way the meter is powered by the ST-Link and you need to make sure to switch it on or the CPU will be kept in reset mode.
I used the LowZ range, but other ranges will probably work too.
Start openocd with:
--- Code: ---sudo openocd -f 121gw.cfg
--- End code ---
And the connect to it in another terminal with:
--- Code: ---telnet localhost 4444
--- End code ---
tpw_rules:
--- Quote from: chefkoch84 on January 25, 2018, 07:13:21 pm ---p.s. - perhaps somebody finds the source for this firmware on a USB-stick in the dumpster (next to a 500k$ scope or something ;-)
If so... it would be a very nice move to upload it here...
--- End quote ---
If I may toot my own horn a little bit, I'm already ahead of you. If you're interested, check it out here and feel free to contribute to the wiki.
--- Quote from: Iagash on January 25, 2018, 06:23:34 pm ---I hooked up the 121gw to my st-link and seem to be able to dump the flash.
I also tried to read out the option bytes from the cpu.
--- End quote ---
Thank you so much for both of those (along with the cal data from earlier) and the detailed instructions you provided on doing it yourself. I've added all three things to the GitHub. By the way, your meter has version 1.02, correct? That's what the dump seemed to indicate.
Iagash:
--- Quote from: Iagash on January 25, 2018, 06:23:34 pm ---I also tried to read out the option bytes from the cpu.
--- End quote ---
I'm not sure about these if I did it right. I'll look into them tomorrow with the datasheet to see if they make sense.
This is my first encounter with STM32, I just used AVRs up to now. I'll have to do a lot of reading.
--- Quote from: tpw_rules on January 25, 2018, 10:24:51 pm ---By the way, your meter has version 1.02, correct? That's what the dump seemed to indicate.
--- End quote ---
Yes this is correct.
Thank you a lot for your work investigating the firmware! This is very interesting.
I get you are also one of the early backers and you meter is stuck at UEi in the US. If you don't mind a wobbly switch, Dave might be able to poke them a bit to send your meter out early.
Edit:
And also a lot of thanks to Dave and UEi for not setting the readout protection on the STM32! I sincerely hope they don't regret it.
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