The invention provides for a sideband signal for the USB that has real-time interrupt capabilities. A system and method for hardware detection of an interrupt signal provides for the ability to superimpose a high frequency interrupt signal on a USB power line for transmission to a controller. Alternatively, an overcurrent flow may be generated from a peripheral device and detected by an overflow current detector on the USB. In response, the overflow current detector may output an interrupt/overflow current detection signal to the controller.