Method and system for configuring a serial interface. The system includes one or more input nodes each coupled to a corresponding serial bus. One or more output nodes are coupled to a respective serial bus, each output node having a respective driver. A voltage detection circuit determines the voltage at a configuration node. Mode of serial bus operation is based on the voltage level detected at the configuration node. In at least one mode of serial bus operation, the configuration node is used as a mode select input and power source for at least one output driver.