Which multimeters use the STM32 Micro?  Ive just reviewed one. - Page 1
Forum section: electronics / general

author: Perrin21
author_rank: Regular Contributor
timestamp: August 07, 2019, 07:59:27 am
content: Hi, does anyone know which multimeters are using the STM32 Microcontroller? I have recently been testing one out (a multimeter based on this micro) and wondered how common this microcontroller is in DMMs. I have noticed there is a large hacking community for these microcontrollers and have just watched Dave's STM32 video showing how the chips can be reprogrammed. Could this be the ultimate hackable DMM? or am i barking up the wrong tree and its quite common? Its not what i expected to find when i tore it apart.Review herehttps://youtu.be/xRkMdbNCBWo

author: ogden
author_rank: Super Contributor
timestamp: August 07, 2019, 08:39:10 am
content: Quote from: Perrin21 on August 07, 2019, 07:59:27 amI don't know any, but you can tell more about the one you tested. PCB pictures will help too.QuoteAny pointers to stm32 *hacking* community?

author: Perrin21
author_rank: Regular Contributor
timestamp: August 07, 2019, 09:42:39 am
content: That's interesting. I have one here. Very cool. That should at least make the teardown more interesting. Will share more details very soon, I'm just working on the video now. Could be a nice hackable meter then1000V Cat 4 too.

author: Perrin21
author_rank: Regular Contributor
timestamp: August 07, 2019, 09:54:45 am
content: here is a teaser

author: ogden
author_rank: Super Contributor
timestamp: August 07, 2019, 11:11:57 am
content: Quote from: Perrin21 on August 07, 2019, 09:54:45 amTeaser?Can't you tell make and model of multimeter? Yes, indeed there is stm32 inside. So what? Most likely you can't read-out it's firmware anyway (unless you are ready to invest significant amount of money). It means no *hacking*. You have to swap chip on PCB with new one and *develop* stm32 code from grounds-up. Before that you have to reverse-engineer and analyze circuit of device to fully understand it's operation so you can write code that actually works. All that for what exactly? - To prove that you can do it? Good luck with that. I mean it."Improvement"of instruments is recurring topic here. Most of those who actually want to use instruments will just use them as is. Serious engineer do not want to debug device he is building with tool he can't rely-on, that needs to be debugged itself.

author: Kean
author_rank: Unknown
timestamp: August 07, 2019, 11:16:06 am
content: Quote from: Perrin21 on August 07, 2019, 07:59:27 amYou know that Dave's 121GW DMM uses an STM32L152 don't you?

author: 001
author_rank: Super Contributor
timestamp: August 07, 2019, 11:55:03 am
content: Quote from: Perrin21 on August 07, 2019, 09:54:45 amWhy so pathetic? It is only EE forum

author: ebastler
author_rank: Super Contributor
timestamp: August 07, 2019, 12:14:41 pm
content: Quote from: Perrin21 on August 07, 2019, 09:54:45 amYeah, man, you have uncovered the ultimate business model. Buy those secret multimeters, hack them up to 10 times better resolution and add an on-board Tetris game, then sell them for twice the price. Better make sure nobody figures out the DMM brand!

author: coromonadalix
author_rank: Super Contributor
timestamp: August 07, 2019, 12:20:42 pm
content: Why double posting in the microcontroller section ?Annoying to say the least.thread removed

author: ogden
author_rank: Super Contributor
timestamp: August 07, 2019, 01:27:15 pm
content: As we know that Dave's DMM uses this exact stm32 kind, it could be Brymen 869S? Other option would be Megger AVO835?

author: coromonadalix
author_rank: Super Contributor
timestamp: August 07, 2019, 03:24:56 pm
content: Another going nowhere thread ....... unless Perrin21 show us a video of photo(s) or model name and brand, this thread should stop here.

author: gamalot
author_rank: Super Contributor
timestamp: August 07, 2019, 04:36:29 pm
content: EEVBlog 121GW

author: MosherIV
author_rank: Super Contributor
timestamp: August 07, 2019, 09:16:57 pm
content: I think the Fluke 287/289 both use an STM32F of some kind.How hackable are they?Firstly, someone has already mentioned that the firmware is likely to be protected, it is near impossible to read out.Secondly, there are over 100 variants of the STM32F line of micros. Even if you know the specific micro, with all the peripheral options, knowing what all the io pins are doing means reverse engineering the entire circuit.Thirdly, The original source code is likely to be in high level language like C. So the amount of binary/assembly code is likley in 100s Kbytes. Then you have compiler optimisation to get your head around.Simple answer - not very. Only the really, really, really, really determined will even try!

author: gamalot
author_rank: Super Contributor
timestamp: August 07, 2019, 11:35:59 pm
content: Quote from: MosherIV on August 07, 2019, 09:16:57 pmMCU used in Fluke 287/289 is MSP430 from TI:https://www.eevblog.com/forum/reviews/fluke-287-dmm-teardown-and-photos/

author: Mr. Scram
author_rank: Super Contributor
timestamp: August 07, 2019, 11:42:16 pm
content: Guess what I had for supper last night? I'm not going to tell you but I'll give you a hint. It came on a plate.

author: ogden
author_rank: Super Contributor
timestamp: August 08, 2019, 01:01:15 am
content: Quote from: Mr. Scram on August 07, 2019, 11:42:16 pmYou think we want to know but whole sensation of revelation is just your illusion

author: Mr. Scram
author_rank: Super Contributor
timestamp: August 08, 2019, 07:01:29 am
content: Quote from: ogden on August 08, 2019, 01:01:15 amConsidering the number of revelation teaser threads lately that can't be right.

author: DaJMasta
author_rank: Super Contributor
timestamp: August 08, 2019, 06:21:28 pm
content: Quote from: Mr. Scram on August 07, 2019, 11:42:16 pmFancy schmancy, you didn't have to eat it off some wax paper/paper bag?I also don't understand the secrecy. As far as I know, every STM32 is reprogrammable, so it would be hackable with commonly available tools. Also not uncommon among meters, it's a fairly standard, fairly good, fairly cheap micro from a reputable brand name, and it makes for a good light-duty low power application processor.

author: ogden
author_rank: Super Contributor
timestamp: August 08, 2019, 06:55:13 pm
content: Quote from: Mr. Scram on August 08, 2019, 07:01:29 amTeaser of revelation does not guarantee that it will be delivered in the end. That's actually The Point.

author: ogden
author_rank: Super Contributor
timestamp: August 08, 2019, 07:06:15 pm
content: Quote from: DaJMasta on August 08, 2019, 06:21:28 pmIncorrect. Read-out protection level-2 disables all debug interfaces leaving only bootloader as means for reprogramming. If bootloader is vendor-specific or what's worse - uses firmware encryption, you are out of luck reusing such stm32 IC especially "with commonly available tools".

author: MosherIV
author_rank: Super Contributor
timestamp: August 08, 2019, 08:23:54 pm
content: QuoteIf by 'hackable' you mean wipe and re-program from scratch. Yes.If you mean read out and modify single bytes to modify the existing program -NO.I refer you to ogden's comment and if you manage to read out the existing code I refer you to my ealier postQuote

author: Nornand
author_rank: Newbie
timestamp: August 08, 2019, 08:50:53 pm
content: Hacking a secured STM32FOhttps://www.aisec.fraunhofer.de/en/FirmwareProtection.html

author: ogden
author_rank: Super Contributor
timestamp: August 08, 2019, 09:07:11 pm
content: Quote from: Nornand on August 08, 2019, 08:50:53 pmTo do the "hacking", in this case flash readout, protection level must be downgraded from RDP2 to RDP1 using UV EEPROM eraser on previously decapsulated chip. It can't be considered as "reprogramming with commonly available tools"Quote from: MosherIV on August 08, 2019, 08:23:54 pmNo. You can't wipe nor reprogram RDP2-protected stm32.

author: MosherIV
author_rank: Super Contributor
timestamp: August 10, 2019, 09:54:46 am
content: QuoteI have not worked with ST parts now for more than 5 years but I thought that using SWD/JTAG to disable RDP2 would result in wiping the flash and hence allow reprogramming. My bad if I am wrong.

author: ogden
author_rank: Super Contributor
timestamp: August 10, 2019, 10:34:17 am
content: Quote from: MosherIV on August 10, 2019, 09:54:46 amHow could you disable RDP2 with SWD/JTAG when main function of RDP2 is to disable SWD/JTAG?!

author: Mr. Scram
author_rank: Super Contributor
timestamp: August 10, 2019, 01:22:51 pm
content: Did we get an answer from OP yet? If not it's time to close the thread.

author: Kean
author_rank: Unknown
timestamp: August 10, 2019, 03:25:09 pm
content: Quote from: Mr. Scram on August 10, 2019, 01:22:51 pmI presume you mean the "answer" to the teaser?Because OP's original question has been answered: it is somewhat common, and without more info I suspect the EEVblog 121GW is most likely more hackable due to the published schematic and microSD slot.Plus, some significant work has already been done on reverse engineering the 121GW beyond the schematic ...https://github.com/tpwrules/121gw-reIf you just want a well documented multimeter circuit to hack into your own design, then Digilent have thishttps://store.digilentinc.com/dmm-shield-7-function-digital-multimeter-shield/

author: ebastler
author_rank: Super Contributor
timestamp: August 10, 2019, 03:46:51 pm
content: Quote from: Mr. Scram on August 10, 2019, 01:22:51 pmNo, the OP hasn't been back on EEVblog since three days. Busy building his new multimeter business, or turning his scoop into a full-length movie, I presume.

author: CDaniel
author_rank: Frequent Contributor
timestamp: August 11, 2019, 08:03:47 am
content: For a fully functional multimeter with a mature firmware , what is the point for "hacking" ? You can't add features or improve it . The 121GW , as it is now , is not used to the max and has some deficiencies, that why the haching and improving the firmware could be very usefull .

author: coromonadalix
author_rank: Super Contributor
timestamp: August 12, 2019, 07:23:04 am
content: Seems this meter, a video has been madehttps://www.eevblog.com/forum/testgear/ive-reviewed-the-megger-avo835-this-feels-like-it-fell-under-the-radar/new/#new

author: ogden
author_rank: Super Contributor
timestamp: August 12, 2019, 07:39:03 am
content: Yes, well-made video.

author: Perrin21
author_rank: Regular Contributor
timestamp: August 12, 2019, 10:06:17 am
content: Quote from: ogden on August 12, 2019, 07:39:03 amThanks, im very new to all this. Glad you liked it.

author: Perrin21
author_rank: Regular Contributor
timestamp: August 12, 2019, 10:09:16 am
content: Quote from: ebastler on August 10, 2019, 03:46:51 pmHaha, you have no idea. Filming and editing the video has been non stop for the full week. Even deciding if i should just do a basic unboxing or go into deeper depth wasn't easy to decide as you can see from some of the comments here. I have been editing for 5 days solid and the result is a 12 min video lol. Don't know how most youtubers manage to release content so fast.

author: Black Phoenix
author_rank: Super Contributor
timestamp: August 12, 2019, 10:13:39 am
content: Quote from: Perrin21 on August 12, 2019, 10:09:16 amWe can talk again one year from now when you released a lot more videos... With time you will start getting shortcuts and knowing where everything is plus improving your workflow.

author: Perrin21
author_rank: Regular Contributor
timestamp: August 12, 2019, 10:13:58 am
content: Quote from: Kean on August 10, 2019, 03:25:09 pmIn many ways this was the scope of the question, to establish if id found gold or tin. I haven't taken apart enough meters to know if the STM32L152 is common amongst them or if its a rarer find. I also come from more of a hacking background so like to tweak things to do things they shouldn't. Someone joked about Tetris, i have a remote control I've made do that already lol. Even making it flash on continuity would be useful to someone. I think id feel warm inside if i powered it up and it said PWND but hey, its the little things.I think you can see from my video and the way i went about it that i didn't want to make just another multimeter video (even if some would have preferred that) because it isn't me. I prefer to try and find out what something can't do rather than just see what it already does.

author: Perrin21
author_rank: Regular Contributor
timestamp: August 12, 2019, 10:22:16 am
content: Quote from: ogden on August 07, 2019, 11:11:57 amAll good points and i don't disagree with anything you have said. I wasn't looking to offend with the term Teaser. Please allow me some intrigue for the efforts I've made to make a video review of a meter that isn't commonly known. I hope you have enjoyed the video and at least its a tiny bit more insight than the community otherwise had into this product. My channel isn't monetised as i don't have enough subscribers or views yet so this is a lot of work for no financial reward (over a weeks worth). Im hoping i can make content that gets views over time rather than just over the first few days. Its an early first effort at doing a proper review and promoting it. Don't be too harsh lol.

author: Perrin21
author_rank: Regular Contributor
timestamp: August 12, 2019, 10:27:53 am
content: Quote from: ebastler on August 10, 2019, 03:46:51 pmNo multimeter business, just trying to make a youtube channel worth watching. I guess i didn't realise how tough the audience is lol.

author: Perrin21
author_rank: Regular Contributor
timestamp: August 12, 2019, 10:30:12 am
content: Quote from: Black Phoenix on August 12, 2019, 10:13:39 amMy experience of Final Cut Pro is this one video, im learning as i go.

author: Perrin21
author_rank: Regular Contributor
timestamp: August 12, 2019, 06:15:25 pm
content: Quote from: Mr. Scram on August 10, 2019, 01:22:51 pmHere is the answer you desirehttps://youtu.be/xRkMdbNCBWo

author: ogden
author_rank: Super Contributor
timestamp: August 12, 2019, 06:41:45 pm
content: Quote from: Perrin21 on August 12, 2019, 10:22:16 amNo worries. Production quality is very good, well above average in the category. Looks like expensive enough commercialImpressive start. Hope that you have next trick in your sleeve already.

author: CDaniel
author_rank: Frequent Contributor
timestamp: August 12, 2019, 07:26:05 pm
content: Video is good , but implying is a competitor or somewhat equivalent to Fluke 87-V is a little farfetched if you look at the specs ... I don't think you will get many viewers with such exaggerations

author: Perrin21
author_rank: Regular Contributor
timestamp: August 12, 2019, 07:42:47 pm
content: Wow that's some compliment for my first proper video. Thanks, glad you liked it. I had an idea in my head how i wanted it to look but once you start adding flashy FX it does start to look like an advert lol. I tried to rein it back in but i also wanted it to look as professional as possible as im trying to improve my production quality as time goes forward. This video literally felt like it took an age to make but its worth it if people like it. I have seen loads of other DMM videos and many are a lot more technical than i was able to get so i made up for that with 4K and some additional info. Glad you liked it, hope you subscribe.

author: Perrin21
author_rank: Regular Contributor
timestamp: August 12, 2019, 07:47:41 pm
content: Quote from: CDaniel on August 12, 2019, 07:26:05 pmI wasn't trying to exaggerate. Its clear that's what the Product is targeting even if it may fall short in some areas. I have made clear comparisons in the video where they have even appeared to copy some of the Fluke design. I would say the input protection is every bit as good as the Fluke 87V and the board is much more modern in its design and layout. I never gave it a 10 star review and i have been critical in the areas i could see where it fell short. I couldn't put everything or the video would be twice as long and it would have lost the viewer. I watch it and know there were things i forgot to mention but once its up its up. Megger is a very reputable brand here in the UK, every bit as reputable as Fluke and they specialise in much more expensive equipment than the DMM i reviewed. In many ways its a small device to them in the big machine that is Megger.

author: Grandchuck
author_rank: Super Contributor
timestamp: August 12, 2019, 08:19:18 pm
content: Damn good video! Can't wait to see what else you come up with.

author: Perrin21
author_rank: Regular Contributor
timestamp: August 12, 2019, 08:26:32 pm
content: Quote from: Grandchuck on August 12, 2019, 08:19:18 pmMaybe I will even surprise myself, thanks.

author: CDaniel
author_rank: Frequent Contributor
timestamp: August 12, 2019, 08:49:57 pm
content: Quote from: Perrin21 on August 12, 2019, 07:47:41 pmA small advice ... you have to be impartial to be succesfull in this area , I see that you a very big Magger's fan, or they pay you to do it .

author: Perrin21
author_rank: Regular Contributor
timestamp: August 12, 2019, 09:40:47 pm
content: Quote from: CDaniel on August 12, 2019, 08:49:57 pmNo not a fan of the brand as such. I used to have an old AVO2007 when I was 10 that was handed down from a close family member and always loved its industrial design. That was a Metrawatt device they branded. I was recently looking for a new meter myself and started my research here then during my search I thought id check out Megger after trying to find the modern replacement for my old AVO. If you search my posts here you will find that. I then settled on the Yokogawa meter as it felt closest to my aspiration in industrial design but Joe Smith put me off it with his review when it didn't register dangerous voltages. So I decided to take advice given here and got the Brymen 869S which I am very pleased with. I later looked into the Megger AVO835 some more as I liked the look of it but I couldn't find any reviews of it on YouTube bar 1 which was just an unboxing. After talking with Joe he suggested I do my own review of it as I was curious still so the rest is history. I like the device and I had very high hopes for it as its British designed, the more I dug I to it the more I liked it. Is it perfect? no, but its still a nice meter that shouldn't be ignored. My Channel is very new and it's not even monetised, I've made the extra effort in case another brand wants me to check out their gear so I can build my channel. I 100% agree about being impartial, you think they would pay me to chuck their probes in the bin and slate their accessories? I live in Brexit Britain and wanted to see what we had to offer in the space, I wasn't dissapointed with the meter itself, inside its a work of Art.

author: Perrin21
author_rank: Regular Contributor
timestamp: August 13, 2019, 06:09:16 am
content: Quote from: MosherIV on August 10, 2019, 09:54:46 amhow do we know they bothered to encrypt it?

author: ogden
author_rank: Super Contributor
timestamp: August 13, 2019, 06:46:59 am
content: Quote from: Perrin21 on August 13, 2019, 06:09:16 amSolder debug connector, connect debug adapter and check using stm32 debugger or st-link utility - MCU responds to debug interface or not (debugger can ID chip). Be careful doing that - do not execute erase. Such error will brick your device.

author: Perrin21
author_rank: Regular Contributor
timestamp: August 14, 2019, 12:53:31 pm
content: excellent well that confirms what I had planned anyway. let's see what happens. Daves video on the STM32 micro was very interesting