I have a little PCM2704 based circuit assembled from a kit. The chip takes digital input for volume up/down but I would like to replace those with a knob.
Regardless whether the knob is attached to a potentiometer or a rotary encoder, I still need a microcontroller to translate its output to the signals that PCM2704 is expecting.
The chip itself is powered directly from its USB port by 5v, however, it requires <4v for its digital inputs. It provides 3.3v through its SSPND digital output pin (which is always on for my purposes), this is what the kit design uses to feed through the buttons and back into its input pins to control volume.
Now I'm wondering whether I can use the power from the SSPND pin to actually power something like a PIC12F675-I? I know digital outputs can't handle a lot of current but then again.. the PIC chip doesn't draw that much either. From looking at the PCM2704's spec sheet, the output current for that pin(or any digital output) is unspecified.