i am also waiting for circle os 4.3 source files as i have replaced on a primer stm32f103 target the microcontroller by a stm32f407 microcontroller
in the resources setion on this website they have already posted the circle os4.3 but the source files are not included
i want to get these source files for inspiration , and i need to modify them for my particular project as i also have used a different stm32f4xx microcontroller.
on the futur stm32f407 target the have used the 168 pin controller and i use the 100 pin LQFP chip which is pin compatible with the stm32f103 only be take care as it has a different powering scheme, see the stm application note.