Re-use of the PB3/PB4/PA13/PA14/PA15 pin of the GPIO initialization--version of the Register

In order to save IO Resources single-chip opportunity in one IO multiplexing a lot of functions, the general microcontroller with a function can be reused after two functions, which reflects the power of the STM32 Gpio, we use a remap method to map one of the peripherals to the other IO feet, This allows you to take full advantage of on-chip resources!

The following code can be implemented JETG pin, used as a normal pin to use, simple 3 lines of code, the version of the library function is much better.

rcc->apb2enr|=1; Turn on multiplexing function Afio clock
flash->acr|=0x32; Delay 2 Clock cycles
afio->mapr&=0xf8ffffff; Removing the PB34 function of the complex
afio->mapr|=0xf4ffffff;

Re-use of the PB3/PB4/PA13/PA14/PA15 pin of the GPIO initialization--version of the Register