small form factor STM32 boards ...

[Ozone]

Doing a short search, I did not find a board that conveniently fits my criteria for some future projects.
These criteria are the following :
  -  small form factor (not bigger than a Rasperry Pico, preferably smaller (Seed XIAO);
  -  MCU preferably ranging from C0, F0...F3, F40x, L0 or L1; (not an exclusive list)
  -  reasonable commercial availability in Europe;

I intend to use these board as a kind of sensor extension for Linux SBCs, with the Raspberry Pi Zero (II) as favourite. Thus the Pi Zero / Pi Pico format as upper size limit.

I can't specify more IO details yet, but the average peripherals of above mentioned MCU variants suffices for most purposes. But at least 8 or more IO lines should be available. Peak performance and low-power capabilities are not a criterium either.

If someone here knows such a board, I would welcome any suggestion.
Thanks !

[mƎALLEm · Accepted solution]

Hello,

Nucleo-32 format? 

Or STM32C0116-DK:

[Ozone]

Thanks, I didn't notice that the Nucleo-32 format is that small !
I have a few discovery Nucleo-64 and Nucleo-144 boards, which are huge in comparison.
If I am not mistaken, this is the form factor of a DIL-40 package (like e.g. the Z80).

As an additional bonus, the Nucleo's have debug access and an onboard debugger, which many "Arduino" boards lack.

On a temporally related note, it took me a while to log in for an answer, as ST forced my to change my password.
A practice I am not at all happy about. But that is a topic for another thread ...

[mƎALLEm]

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@Ozone wrote:

If I am not mistaken, this is the form factor of a DIL-40 package (like e.g. the Z80).

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This is the real size on a bread board:

[Ozone]

I have a few breadboards of different sizes, so it's still difficult to assess the actual size.
But I checked both the Nucleo-32 reference manual and the (original) Z80 datasheet for measurements, and they are identical within a few millimeters.

[mƎALLEm]

As you can see it fits the DIP-40 socket in width:

[Ozone]

I have seen an interesting application with the Raspberry Pico, which has the same form factor.
The Pico served as a direct plug-in replacement for the CPU in a Z80-based retro computer.

Although, something like the Seed XIAO would be nice.
Same width and spacing, but 14 pins instead of 40. And 11 free GPIOs suffice for a lot of applications.

[mƎALLEm]

STM32C0116-DK has a daughter board that contains the target C0 MCU that fits DIP-20 socket having 16 IOs available excluding debug pins.

From CubeMx based that board selection:

But still you need to plug this daughter board on the mother board for debug, contrarily to the Nucleo-32 board having the onboard ST-LINK. But you still have the access to the bootloader using USART1 over PA9/PA10.

[Ozone]

Thanks, I think I consider this as well.

> But still you need to plug this daughter board on the mother board for debug, contrarily to the Nucleo-32 board having the onboard ST-LINK. But you still have the access to the bootloader using USART1 over PA9/PA10.

I am fine with that, connecting a debug pod to broken out pads or pins is relatively easy.

In contrast to e.g. XIAO or other tiny "Arduino" boards, which usually omit the SWD / JTAG interface, and rely on Arduino (proprietary) bootloaders.