Arduino for STM32

Thank you very much for the answers. I will try to desolder the crystal to verify that the inputs work correctly. As for PA15, I have set up as stevestrong says, but for some reason it still doesn't work as input. Keep investigating.

I am having some problems to configure these pins as inputs because they share other predefined functions at boot.

In the case of PA15 I have disabled the JTAG function so that it isn't used as JTDI. When I try to use it as input, it remains in activated state all the time. Doesn't matter if I set ...

Thanks for the answers. I already found what I was looking for.
Exactly the functions to work directly with ports are GPIOA->regs->REG syntax format for Libmaple Core.

GPIOA->regs->CRL and GPIOA->regs->CRH for configure output, inputo or alternate function.

GPIOA->regs->IDR for Input Data ...

I don't know if I'm posting this in the right section but there goes my question. Is there any function similar to DDRX in Arduino AVR to work with a full port in STM32?
I have been searching and I haven't been able to find anything clarifying about it. In some places they refer to the GPIO concept ...