APM32: New case of double labelling? - Page 1
Forum section: electronics / general

author: Sacodepatatas
author_rank: Regular Contributor
timestamp: November 18, 2023, 01:58:29 pm
content: Recently I purchased some suspiciously cheap bluepills + some stlink clones and, from previous experience (i went overconfident* and purchased 10 pieces 😅), i expected to get the APM32F103CBT6 within them , but I received 10 MCUs labelled APM32FEPSCBT6. The same day I sent an email message to Geehy asking about where could I find resources for such MCU reference, and i was replied by a Geehy representative who told me that the FEPS cannot fulfill the specs of the STM32F103 (i didn't ask him that though) and encouraged me to not use them. In fact he promised to send me at no cost a faster enhanced version named APM32E103 (using his words: their new version manufactured using 55nm process), but, you know, promises are blown with the wind and they didn't ever reply to my second message.Anyway, yesterday I did a small batch of tests by downloading the "BP diagnostics" firmware, and everything ran as expected for the APM32F103 but the one i was testing is the aforementioned APM32FEPS. I figured out that the FEPSCBT6 would have the F103C8T6 die with an extra 64KB of flash added. But i did succesfully test the FPU peripheral that is present in the F103CBT6, then i strongly think that both MCUs have the same silicon inside.Taking into account the manufacturer's response and the strange STM32ForE-BiKe (a STM32F103 labelled STM32FEBK) version made by ST and intended just for the chinese market, I may think that those APM32FEPS are in a similar situation (not intended for use outside china).Do you know anything about this reference? Maybe the same die but with lower quality of silicon wafer and hence lower price?AliExpress Seller is this one:https://a.aliexpress.com/_EvyfjSH*Note: Not really sure if "I went overconfident" is a good translation of what i intend to express. The right expression in spanish is "me vine arriba".

author: DavidAlfa
author_rank: Super Contributor
timestamp: November 18, 2023, 05:33:18 pm
content: Maybe you got engineering samples?

author: PCB.Wiz
author_rank: Super Contributor
timestamp: November 18, 2023, 10:32:37 pm
content: Quote from: Sacodepatatas on November 18, 2023, 01:58:29 pmIt's quite close.We might say 'I went overboard and purchased 10 pieces'https://www.merriam-webster.com/dictionary/go%20overboard

author: PCB.Wiz
author_rank: Super Contributor
timestamp: November 18, 2023, 10:41:22 pm
content: Quote from: Sacodepatatas on November 18, 2023, 01:58:29 pmThe Chinese seem to be loose with their naming.A 32E103 search findsAPM32E103RBT7 Geehy 128KB 20KB FLASH 2V~3.6V ARM Cortex-M3 96MHzGD32E103RBT6 GigaDevice Semicon Beijing 128KB 32KB FLASH 1.71V~3.6V ARM Cortex-M4 120MHz

author: Sacodepatatas
author_rank: Regular Contributor
timestamp: November 19, 2023, 02:54:52 am
content: Quote from: PCB.Wiz on November 18, 2023, 10:32:37 pmSuperb!! That's meaningful indeed. Thanks.Quote from: DavidAlfa on November 18, 2023, 05:33:18 pmThis could be a possibility, but I've seem that since early November, other sellers are receiving feedback from customers stating that they were being sent these parts. Furthermore, on AliExpress I could find two shop that sell them, although one of the shops is not listed from the AliExpress search but directly from Google. And if you perform a search in TaoBao, then you find some sellers that offer this IC with a ridiculous price.https://item.taobao.com/item.htm?spm=a21n57.1.0.0.7fd7523cWfU4Mi&id=741057046058&ns=1&abbucket=14#detailI think these can be compared to the baseline APM32F103CBT6, but they are neither the "enhanced E series" nor the "intermediate S series" as both have 36kB of RAM and my test failed when i tried to read beyond 20kB from address 0x20000000 (though i could try testing again because I didn't test memory boundaries so exhaustively).Quote from: PCB.Wiz on November 18, 2023, 10:41:22 pmIn fact, they like renaming ICs like they were manufacturing them. I sent a message to EMARTXCHIP asking about their ETM32x103 MCUs, and they replied that I should ask Geehy because they were just selling renamed APM32s 🤦🏻‍♂️UPDATE: I tried reading address 0x20004FFC and succeeded, but reading 0x20005000 failed, hence RAM is just 20kB.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: November 24, 2023, 12:19:27 pm
content: I have stopped buying blue pills years ago. The uncertainty of whatever chip they put on it this weeks far outweighs the price difference for me.It's a bit of a shame the WeAct Black pills (with STM32F411) are not completely pin compatible with the blue pills. The Blue pill is not really supported by GRBL anymore so one of my projects is to update it with a black pill, and I have to put in some bodge wires.WeAct also still sells blue pills, and you can choose between STM and (I think) GD variants. They are not the cheapest, but If I still wanted to buy the blue pills some extra certainty would be well worth the extra Euro.

author: Sacodepatatas
author_rank: Regular Contributor
timestamp: November 24, 2023, 04:40:03 pm
content: Quote from: Doctorandus_P on November 24, 2023, 12:19:27 pmI buy them from time to time but without any spectation of getting a real STM chip. In fact, choosing the "compatible MCU" option, usually is cheaper and you can get a idea of what is the "compatible MCU" you are being sent if you take a look on the people giving feedback to sellers.I don't understand why BP manufacturers don't offer already assembled pcbs but no MCU within there so you can fit, in 2 minutes of soldering work, anything you want that has compatible pinout with the F103Cx... Currently I can buy a BP with a STM32F103C6T6 for less than 1€, then I remove that 45ct MCU and fit a nice 65ct CH32V203C8T6 running at 144MHz. If any manufacturer would offer a MCU-less PCB, for, about 50ct, I would purchase 20 pieces for sure. I know this is not a new topic, since many have ordered custom bluepills to PCB manufacturers such as JLCPCB..., and at least one grupDIY purchase has been done before, but not something as easy as in one click purchase.

author: IOsetting
author_rank: Regular Contributor
timestamp: November 24, 2023, 05:50:49 pm
content: So far as I know they are the same.APM32FEPSCBT6 is on sale on Taobao, all described as "a replacement of APM32F103CBT6" or "compatible with APM32F103CBT6". The price is not cheaper than APM32F103CBT6.I don't think Geehy would take trouble to maintain a different die for out-dated M3 types.

author: IOsetting
author_rank: Regular Contributor
timestamp: November 24, 2023, 06:04:55 pm
content: Quote from: Doctorandus_P on November 24, 2023, 12:19:27 pmI stopped buying these boards, too. Since I can order PCBs on jlc.com, I turned to buy the chips instead, which brings much more certainty and flexibility.

author: paf
author_rank: Regular Contributor
timestamp: November 26, 2023, 10:00:55 am
content: Quote from: Doctorandus_P on November 24, 2023, 12:19:27 pmYes. Look for We Act Studio on Ali Express. The boards are good (as far as I can tell) and they sell Blue Pills + with APM32F103CBT6, GD32F103CBT6, CH32F103C8T6, CH32V203C8T6, STM32F103C8T6 and STM32F103CBT6.Shop:https://weactstudio.aliexpress.com/store/910567080Docs on their github:https://github.com/WeActStudio