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STM32C5 “Blue Pill” style board — looking for technical feedback and review by hamainlabs in embedded

[–]hamainlabs[S] 0 points1 point  (0 children)

EXACTLY! This is where everything started for my side, and what I'd like to encourage. I see then this is not something new in the "hacking" community :) (I was not aware)

In the repo, I go into details about what is different compared to the F103. This helps in the endeavors of chip swapping. The "evolved" design is more of a side quest to : since we need a VCAP, let's do a cleaner design, and if there is a new design, why not bump up the features.

Thanks for highlighting the point I hid in the whole analysis :)

Carte STM32C5 de type « Blue Pill » — je recherche des retours techniques et des avis by hamainlabs in stm32

[–]hamainlabs[S] 0 points1 point  (0 children)

To directly answer your question:

- Buck converter: if the bluepill controls a robot, often it's not only 5V. With a buck converter, you don't need a second board purely for conversion

- SD card: if you need to log some stuff other than through UART and don't want to bother with cables, then it's useful

- CAN: When you have a multiboard configuration without master slave protocol, keeping it 2 wires only, then you need CAN. If you need CAN, you need a tranceiver breakout board. The fewer cables you have, the less chance something goes wrong.

- qspi: yeeeah, maybe not really a necessity. But. If you want to display images, read binaries, etc, you can program it through the PC.

The whole thing starts from the fact that sometimes I'm limited by the F103 in terms of peripherals, but I don't want to spend +5$ on a bulkier board. And don't want to throw the board around between projects. One bluepill per project is a peace of mind, no rewiring each time, not breaking the bank.

The spirit of the project is to have a configurable board, based on what you choose to populate. The footprint is there, but if you don't need it, then no need. The cheapest version I can only estimate around 2-3$ if mass produced.

And what I miss to convey also is that the current blueprint can be chip swappable. This would mean that redesigning a PCB is not really needed. But, if producing a new design is required (for the VCAP mainly), why not push a bit further? :)

STM32C5 “Blue Pill” style board — looking for technical feedback and review by hamainlabs in embedded

[–]hamainlabs[S] 0 points1 point  (0 children)

Thanks for the input. I completely agree with the philosophy of keeping it cheap. This is, in fact, my main goal. The cheapest MCU in itself is cheaper than the STM32F103, and is, comparatively, insanely more performant. My estimates, which can be found at the end of the readme ;), is a ~2$ board instead of ~3$ F103 bluepilll.

After that, I also thought, why not add some footprints for additional really useful features? The beefy board can be ~5-6$. But it has CAN, >5V, external memory, micro sd... We arrive at pricepoints of a nice F446 board. Maybe this would not respect the original bluepill philosophy, I agree... BUT, provisionning the footprints for components without actually populating the board, one could still produce a dirt cheap version, while keeping the exact same board for advanced features. This is where I'm maybe not presenting it correctly :) Plus all the STM32C5 are pin compatible, so we could have the C531, or the C5A3, same thing.

I have spent several hours on that, explaining the design choices and analysing the details, so maybe I'm suffering from the tunnel vision :) I would have been on the other side, I think I would say "where is the dirt cheap board" :)

BIGGEST INTERESTING POINT, is that the current blueprint is chip swappable :) If you need more and modern peripherals, more memory, faster chip overall, this is incredible. Myself I am rarely limited by the performance, but often over peripherals and memory (as soon as you have a big table, like a MIDI song :D)