Before connecting the button to the circuit, it is appropriate to consider a bit of circuit theory so that we understand how a button can be used to produce a signal that can be read by a chipKIT (digital) I/O pin. To obtain a signal where the signal voltage properly corresponds to the button's state, we cannot simply attach the button directly to the chipKIT board—there's a little more to it than that. We need to also use a pull-up or a pull-down resistor. If you are unfamiliar with using a pull-up or pull-down resistor with a button, please read the information available via the boxes to the right.