Most microcontrollers now include the options to select the GPIO speed for a certain pin inside a port. Many will announce this feature as GPIO max current control or slew-rate, but in the end they are talking about the same thing. First of all, why would you ever need to control GPIO current? Wouldn’t it be great to leave this at the maximum level at all times? Well, it is usually not that simple, and more so as integrated circuits get larger clock frequencies.