I just came across smol and perked up because I’ve been interested for a while in tiny electronics. I particularly for a while wanted to make a special purpose bluetooth earpiece, in what I guess is now the older style rectangular format rather than Airpod-like with a charging case. The Smol form factor is about right for that, but the right boards aren’t currently available. My suggestions:
* Have a board with the Ambiq (Artemis) cpu instead of the ESP32. That gets the package count down as well as the power consumption. It gives up wifi but retains bluetooth. It could possibly use your Artemis module which is a touch over 10x15mm iirc, and should fit onto a Smol board. It should also have an RTC and a lipo charger and a usb connector, like a tiny Feather. It is tolerable to drop the usb connector if necessary but it would be very nice to have.
In general almost everything I’ve ever wanted to build with a microprocessor has also wanted an RTC, usually for time of day but sometimes even just as a frequency standard. It’s nice that you now have a smol RTC board, but having a separate board for it and yet another separate board for the lipo charger defeats the miniature size of the smol boards, since you now need a stack of them instead of one board. So please put everything on a single board, if you can.
Offer some lipo pouch cells in the exact same form factor (10.5*40mm or whatever it was). Those would charge using the on-board lipo charger from the ambiq smol board, giving a thin sandwich.
If possible, also have a qwiic connector on the ambiq board, but in any case have some simple and tiny way to interface smol to qwiic, maybe with a very short FPC adapter.
It could be nice to have some 3d printed enclosures for small (no pun intended) stacks of boards of different sizes.
Should have a Lora board and a GSM board. I sometimes want an environmental sensor that can send an update as an SMS text or receive a control message the same way now and then. It wouldn’t need expensive mobile data things like M2.
Thanks! STM32 is fine, the idea is to just save some packages compared with the ESP32, to get more functions onto the board. I’ll watch for the new boards! I remember finding there are some super tiny RTC modules like this: https://www.st.com/en/clocks-and-timers/m41t62.html – 1.5x3.2mm including the crystal, which would go nicely on a cpu board. It will be nice if the MCU itself has a PDM microphone input for the voice stuff I had in mind. I think most higher end MCUs do have that these days. Having QWIIC would also be great.
It also seems to me that in this ecosystem, people are going to want to build their own boards that have the function combinations they need in one place. It’s not like Arduino where they don’t mind having 5 different boards and shields plugged together. So it would be great to have kicad files of some basic boards available, that people can use as templates, if they are not already there. It could be cool to have a template with 4-pin USB PCB contacts at one end, like a digispark. I’m imagining a 2-board sandwich with your STM32 board plus a multi-function user designed board. That’s way better than five single function boards.
Another application area for smol might be lightweight flying drones, so that suggests a board with pressure transducers, motor controller, etc. Maybe camera input? Compactness and light weight are important here, but power consumption isn’t really a constraint since the flights are short.
Could you put some photos up, of smol boards stacked using the fpc connectors?
I should add, I’m a programmer but not really a hardware guy, so I don’t know what I’m doing in this area and I’m not always sure what is realistic.
I’ll keep thinking. There have been many times I’ve had a gadget idea but felt that the available mcu boards were too big and that I don’t have the skills/tools/equipment to build my own. It’s just that none are coming to mind right now, other than the above.
Added (can’t edit any more): another thing I wanted to make a while back was a small security token that would look like a car alarm remote with a pushbutton, but that project got tanked and now everyone makes stuff like that. Smol would have been nice to have back then though (we made a custom pcb instead, with an 8 bit cpu). I had forgotten all about this til just now.
I also just noticed that the company that makes the Xiao board now has a couple of Bluetooth models, one with an on-board PDM mic and 6-axis IMU sensor, interesting. Both have on board lipo chargers. So this gets pretty close to what I was describing further up. They use the Nordic MCU with Cortex M4F, 256k ram, and 1MB flash (not sure if the flash is on chip). They have about the same board area as Smol so there is activity in this space! It also seems to me that these quite powerful microprocessors have gotten a lot cheaper. The ESP32 used to be leagues ahead of everything else that didn’t cost drastically more.
It would be great if you sold those, along with an FPC adapter gadget that would connect the smol board to a usb plug. I think the enclosures exist in other sizes too, if that one is not quite big enough. A thick one that could hold a two board sandwich would also be interesting. I guess a type C version would also be needed.