I have a pin that goes high (1.5v) when a button is pressed but when it's not pressed it's at .4v which the microcontroller can't see as "low". Basicly I need the microcontroller to see this .4v as low.

The microcontroller's VCC is 3.0v. I thought there was a way to compare a pin's volatage to vcc which I thought would make this happen but I forgot how.

Any help would be appreciated.