There are many Arduino “shields” out there, i.e. boards which fit on top of the Arduino Uno and compatibles. Even for one-off prototypes, it may make sense to use this form-factor, as it allows you to re-use a setup with a different µC board underneath (but watch out for 3.3V/5V issues!).
This could be convenient with STM’s low-cost “Nucleo” boards - letting you switch to a different µC if the current one runs out of steam, or doesn’t have all the needed peripherals after all. Or switch to a different line of µCs altogether. Arduino shields have become a de facto standard.
Here is a “base board” for the Hy-Tiny, as described in a recent article and as used before:
It brings out all the pins in the proper place, i.e. to support serial I/O, I2C, and SPI on the same pins as an Arduino Uno. There are even three “spare” pins, available on an extra top-left header.
The Hy-Tiny base board is 50 x 50 mm, just right for production through one of the low-cost PCB services in China. The design files can be downloaded via this link to GitHub.
As you can see, all headers are doubled-up on the inside, without that 0.06” alignment error of standard Arduino shields. This board can be used with run-off-the-mill prototype boards with a “sea of holes” on a 0.1” grid. Such as this one, which is 5 x 7 cm and has 24 x 18 solder islands:
The idea with the above Hy-Tiny base board therefore, is to select the header rows needed for a particular project and only solder those in. This approach is not new: several existing boards (e.g. the Olimexino-STM32) offer exactly the same solution for that off-grid alignment issue.
Coming up next: even more flexibility!