Arduino for STM32

I don't want to use the boot pin every time I program my board.

Is there a way to do this?

If I write my own bootloader, can I solve the above problem?

Can I modify the embedded bootloader?

I was not familiar with the systick interrupts and it took me a minute to realize that STM core was different from Roger Clarks. Arduino STM32" but adding "systick_attach_callback &encoder1_read" in setup made it run perfectly on my blue pill running Roger Clarks "Arduino STM...