A bi-directional single-conductor interface is provided, comprising (1) a switching means for applying a voltage level to the interface that is outside a normal voltage operating range for the interface and for removing the applied voltage level at an end of a specified time duration; and (2) a timer initiated by detection of the applied voltage and arranged to include a timing interval following removal of the applied voltage. With the interface of the invention, data is caused to be transmitted via the interface in a first direction during the timing interval of the timer, and in an opposite direction during other times.