Newbie Question: STM32F103 or newer equivalent for new project?

Grant Bt · ‎2020-11-03

So the Blue Pill guy checks almost all the boxes for a new project I'm working on soon. 3 UARTS, M3, 72MHz, USB device, cheap, powerful *but* I'm not clear on the "fix" for being able to re-enumerate my device on USB. I must be able to change device types under firmware control (host re-enumerates device from say CDC to MSD or whatever). I've seen comments about workarounds and adding external transistors, but I don't know really how to do it. So, any pointers please.

Alternatively, I could use something newer if it checks all the same boxes (not substantially slower for instance) and is within $1USD of the F103 at 1k quantities. Recommendations? I have spent way too long on the Product Selector that I feel I need human input here. I don't need low power, FPU, DSP, but if they are there that's fine.

Thanks!

frackers · ‎2020-11-03

Rather than 'Blue Pill', take a look at 'Black Pill' which has a choice of f401 or f411. Make sure to get the latest V3 PCBs, there are a lot of sellers flogging off older versions.

BTW: The last Blue Pills I got had fake f103 on them - took a lot of time to find the ID so the debugger would work and I'm still not convinced they have duplicated all the RTC 'features'.

Grant Bt · ‎2020-11-04

Thanks. That's interesting. I only used the Blue Pill as a minimal get-to-know the part (rather than the NUCLEO which I do have also). The F401 looks interesting and it seems "more" than the F103 and is cheaper. I'll have to double-check that though. Mouser comparison @Q1k for 128k at LQFP64:

STM32F103RBT6 M3 72MHz $3.11 
https://www.mouser.com/ProductDetail/STMicroelectronics/STM32F103RBT6?qs=bhCVus9SdFv12dJRZaBmJg%3D%3D
 
STM32F401RBT6 M4 84MHz $2.51 
https://www.mouser.com/ProductDetail/STMicroelectronics/STM32F401RBT6?qs=4ccVDqXDOrn4COlKBEB%252BDA%3D%3D

I found the Canaduino Blue Pill boards genuine and correct and they have a Black PIll one too.

Uwe Bonnes · ‎2020-11-05

I very much like the STM32L41/3 these days. More space and better peripherals than F1 and similar prices. For small board lot at Nucleo-32. More expendive than xxPill but with garanteed genuine STM32 and built in debugger.

Grant Bt · ‎2020-11-05

Thanks. I'm numb from the possibilities. These are top candidates so far, but I also want to make sure that I start with something popular/common rather than an obscure variant that has less of a knowledge base or price competitiveness. Probably I will use QFP48 or QFP64, and flash of at least 128k or 256k.

STM32F103RBT6 M3 72MHz 128kFlash

STM32F401RBT6 M4 84MHz 128kFlash

STM32L433RBT6 M4 80MHz 128kFlash

STM32F411RCT6 M4 100MHz 256kFlash

USB Device and 3+UARTs again are also essential, along with performance similar to these above. I long for the days of the FAE (field application engineer) visits.

GB

Uwe Bonnes · ‎2020-11-06

STM32L433RBT6 has the modernest set of peripherals, F103 the oldest and fewest RAM.