New APM32F103CB

[blue-man]

Have you tested it under STM32 Core and if so, which option did you select under Board part number?

TIA

The tests have been made from another one (pegel) with the Original STM developement environment.
You can read the original Thread here https://www.mikrocontroller.net/topic/492672#6258732 but it is in german.
The Link starts where the FPU could not be detected.

At this point https://www.mikrocontroller.net/topic/492672#6258842 it becomes more clear
and then i found the above documentation https://www.apexmic.com/uploads/tool/MC ... 496340.pdf.

Result: viewtopic.php?p=2710#p2710

[Kenjutsu]

FPU issues aside, does it work under STM32 Core and if so, which option did you select under Board part number? If it works as a standard Blue/BlackPill with confirmed 128k flash, then it is still a good board to buy, IMHO.

TIA

[blue-man]

FPU issues aside, does it work under STM32 Core and if so, which option did you select under Board part number? If it works as a standard Blue/BlackPill with confirmed 128k flash, then it is still a good board to buy, IMHO.

I used "BluePill F103C8" so far and it works good.
(USB, Ports, ADC, Timer)
But i didn't test the MCU funtionality in detail.

I can't say if this "clone" is better than other ones.
Maybe you can report this here?

[Kenjutsu]

Thank you for the feedback. Currently, I do not have any of these boards, but I am interested in buying some since Robotdyn products are better quality than most no name products on eBay/AliExpress.

[blue-man]

Yes - why not.
It would have been a nice extra if the additional features would be present.
So it is "only" a nice clone with definite more Flash.

[fanoush]

Hi, just found this thread about APM32F103 chip.
Recently I got STLinkV2 clone with genuine Geehy APM32F103CBT6 chip and it looks like the FPU is working for me

The chip looks like this

datasheets are available here https://www.geehy.com/apm32?id=14

FPU is documented in the APM32F103x4x6x8xB User Manual pdf
I just enabled it via bit 2 of 0x40021014 and then followed manual - started fpu with operation division to register 0 (base for FPU is 0x40024000), wrote 2 arguments to 0xc and 0x10 and the result was in 0x8 register after register 0x4 showed operation is done via 1

I got this stlinkv2 clone from this aliexpress item https://www.aliexpress.com/item/1005001621626894.html but no guarantee you'll get it too (order was placed Apr 9, 2022 and I got it today).

So to sum it up this is not E variant of the chip and the FPU is working.

And BTW I flashed the dongle with Espruino JavaScript interpreter https://github.com/fanoush/EspruinoBoar ... r/STLINKV2 so testing FPU was just a few poke32/peek32 calls

Code: Select all

>var f=new Float32Array(3)
=new Float32Array(3)
>var i=new Int32Array(f.buffer)
=new Int32Array(3)
>peek32(0x40021014).toString(16)
="14"
>peek32(0x40024000).toString(16)
="3130342a"
>poke32(0x40021014,0x14+8)
=undefined
>peek32(0x40024000).toString(16)
="0"
>poke32(0x40024000,1+22*2)
=undefined
>f[0]=0.5
=0.5
>f[1]=2
=2
>poke32(0x40024000+0xc,i[0])
=undefined
>poke32(0x40024000+0x10,i[1])
=undefined
>peek32(0x40024000+0x04)
=1
>i[2]=peek32(0x40024000+0x08);f[2]
=0.25
> 

[fanoush]

Just a small follow-up with this APM32F103CBT6 chip. I also tested running this chip at 96MHz with USB and it works too. For running at that speed it needs increased flash latency (from 2 to 3, FLASH_ACR register) and there is also extra divider 2 for usb clock. With those two changes and PLL multiplier 12 (instead of 9 for 72) it runs fine.

I got stuck a bit first because the RCC_CFGR register in STM32F103 has USBPRE prescaler defined as single bit so extending values 0,1 with 2 needed extra fixes in RCC_USBCLKConfig() method as the code was using bit banding Cortex-M feature to set single bit 22, APM32 is using reserved bit 23 too to make it two bit value.


EDIT 20 May 2022: I made another order from aliexpress store linked above and again got this exact Geehy F103CBT6 chip.

[linkenzaney31]

I really like RobotDyn products and have been using them for several years.
I was tempted to purchase the APM32F103CB board, but then realized that life is too short to fight against or run with the wind mills.

Now, I have turned a new leaf in my MCU projects and will focus on the F411 and H750 boards for device connected systems.
For distributed systems, I would like to have a genuine alternative from STM for ESP32 and RPI4.