Patent ID: 8891217

Claim:
An input/output interface circuit operable in first and second modes, comprising: a source of electrical current; an input/output node; a diode connected between said current source, and said input/output node to prevent current from flowing through said input/output node into said current source; a first switch interconnected to substantially short circuit said diode, when closed; a second switch interconnected to form a conductive path from said input/output node to ground, when closed; a measurement node, between said current source and said diode, for measuring a voltage at said input/output node; wherein in said first mode, said first switch is closed and said second switch is open; and in said second mode, said first switch is open and said second switch may be selectively opened or closed; wherein said input/output node is for providing current to a sensor circuit in said first mode and for receiving current from an output circuit in said second mode.