GPIO_AF_SEL_CLR=no
GPIO Alternate Function Clear. Writing a 1 to one or more bits in this register clears the bits in the same positions in GPIO_EN1 to 0, without affecting other bits in that register.
GPIO_AF_SEL_CLR | Mask of all of the pins on the port. 0 (no): No effect. 1 (clear): Clear the corresponding bit in GPIO_AF_SEL register. |