PIO LEDs always on

In sopc builder have you defined this pio as output only or bidir? If the latter, you need to set the direction bits for outputs.

Check also in Quartus project if all connections are ok and signals are assigned to right pins.

Regarding your question about pointers, using char is not mandatory. Infact you can use int when your pio is up to 32bits wide.

Probably all samples use char because this is the native addressing mode of processor.

Cris