Inventors:
Donald A. Stoye - Santa Clara CA
Assignee:
Sun Microsystems Inc - Palo Alto CA
International Classification:
G09G 500
Abstract:
A remote power key function is implemented between a remote input device having a power key and a host computer system using a four lead USB interface. Normal functioning of the USB interface and of the input device are not affected. An input device includes a remote logic circuit comprising a transistor, a diode, and a low voltage battery. The remote logic circuit and MPU receive a first input from the power key and battery and receives a second input from the host-computer provided power supply that is "1" if the host computer is powered-up, and is "0" otherwise. Remote logic circuit output is coupled to the D+ USB interface line, and MPU output is coupled to the D+ and D- interface lines. Clamping latch logic within the host computer has a first input that is the D+ line, and a second input that is the power supply "1" or "0" signal. Latch logic output is input to the latch input port of the host computer power supply.