Why do we need to set speed for GPIO Output pins in STM32?
Just for remind :
For Input pins, The STM32F4 Reference Manual on page 278 says that:
The data present on the I/O pin are sampled into the input data register every AHB1 clock cycle.
So for the GPIO pins when they are used as INPUT, speed is Constant and equals to AHB1 Clock.
But if they are configured as Output we have to set their speed, So the question is what does it mean to a pin to have several speed modes when its is configured as Output?