Look at how large the sectors/pages are.
Shrink the memory size described in the linker script or scatter file so the pages you want to use are at the end of the flash memory space.
The STM32F103C8T6 is 64KB as I recall, pages perhaps 1KB (check the manual). Tell the linker you've only got 63KB, which will give you the page to manage directly.
You can then access a structure you create in the memory, and cast a pointer to it at 0x0800FC00
Add additional code to erase and write the page with new content, reflecting your configuration.
