I am waitng for this very cheap Maple Mini sort of clone
- http://www.rogerclark.net/stm32f103-and-maple-maple-mini-with-arduino-1-5-x-ide/
- http://www.sunspot.co.uk/Projects/Arduino/STM32/STM32.html
- https://www.hackster.io/rayburne/maple-mini-clone-update-74468b
Chip ATmega328 (Uno etc) |STM32F103C8T6
Speed 16MHz |72MHz
Flash 32 KB |128 KB
RAM 2 KB |20 KB
Power 5V |3
(don't know how to 'format this.. sorry 
)