Arduino Pro Mini maximal and recommended current per pin In Arduino Pro Mini (3.3V) specs indicated the maximal and recommended current per pin, 40mA and 20mA respectively. Does these values means input current (i.e. safe input current Arduino can handle) or output current?
It is the amount of current the pin can source or sink when in OUTPUT mode.

That is, the amount of current that can flow from the pin to ground, or can flow from VCC into the pin.

You can understand it better if you learn how a GPIO pin works.