New APM32F103CB

[Pito]

Good!

So, just a simple single-precision floating point ALU with Cordic exposed in peripheral address space.

No SIMD vector or MAC operations and no saturation, so almost useless for all DSP usage.

Better than nothing

I doubt there will be Cordic. They do it standard way, imo.

[blue-man]

I received now some of the APM32F103CB black pills from RobotDyn.

Today I tried to use the library from the SDK to compile a little first test program of the FPU.
But it seems the beginner needs a tip how to use this precompiled library sc_math.lib in STM32Duino.

I get the compile error:

Code: Select all

.../arduino15/packages/STM32/tools/xpack-arm-none-eabi-gcc/9.2.1-1.1/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/bin/ld: /tmp/arduino_build_835900/sketch/APM-Test.ino.cpp.o: in function `loop':
APM-Test.ino.cpp:(.text.loop+0x26): undefined reference to `sc_math_sin(float)'

I already tried to rename the .lib to .a or .so without success.

[blue-man]

The compilation problem is principally solved viewtopic.php?f=39&t=405 - but leads to other errors ..

[blue-man]

The really disappointing thing is that the APM32F103CB has no FPU !

The MCU of the black pill from RobotDyn is described with an FPU https://github.com/RobotDynOfficial/Doc ... -MCU-Board
Now i found out that only APM32E103 models have an FPU! https://www.apexmic.com/uploads/tool/MC ... 496340.pdf
The E stands for Enhanced.

So this black pill can be seen as an blue pill with 128KB flash memory.

[ozcar]

The really disappointing thing is that the APM32F103CB has no FPU !

I was just looking at the Robotdyn site yesterday and saw there where they say "with a higher frequency 96MHz (1.5DMIPS) and a built-in FPU". They go on with more about the benefits of having the FPU.

So did you advise them of this? Maybe they did not know they were lying?

Edit: I just noticed that the 96MHz is also only the Enhanced version.

[fredbox]

Looks like bootsector already reported this to their github.

[blue-man]

So did you advise them of this? Maybe they did not know they were lying?
Edit: I just noticed that the 96MHz is also only the Enhanced version.

Yes - an dispute is opened with the correct informations.

[fredbox]

Quoting from a different thread:

I would love to hear how well the APM32 functions. It seems very promising, except the costs are a bit high for smaller quantities. I am particularly curious if USB is fully functional at the higher clock rate, and whether power usage is comparable.

20 pieces from the RobotDyn store on Ali is about $29. There is a discount for 20 pieces and free shipping over $25. https://www.aliexpress.com/item/4000807291937.html
I've noticed that Ali now charges state sales tax.
I paid nearly that much for the original Arduino many years ago.

[blue-man]

Please remember that all additional functionality maybe only when you get the APM32E103 !
But i have never seen an offer for it.

So you get an "STM32F103-Clone" with 128KB flash memory - not more.

When you compare the dies you can see that there is no additional space for such a FPU-logic.
APM32F103C8T6: https://www.richis-lab.de/STM32_05.htm
CKS32F103C8T6: https://www.richis-lab.de/STM32_03.htm


The same chip has been used on a Blue-Pill as STM32-Fake.

[Kenjutsu]

So you get an "STM32F103-Clone" with 128KB flash memory - not more.

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

TIA