Patent ID: 7278047

Claim:
A method for operating a printer having a Universal Serial Bus (USB) interface connectable to a first computer and having an Ethernet interface connectable to a second computer, wherein the USB interface operates at a USB clock frequency and the Ethernet interface operates at a different Ethernet clock frequency, wherein the printer communicates over only one of the USB and Ethernet interfaces at the same time, and wherein the method comprises the steps of: a) obtaining a clock source having a set base frequency; b) obtaining a phase lock loop circuit adapted for switching between operating at the USB and Ethernet clock frequencies when driven by the clock source; c) driving the phase lock loop circuit with the clock source; d) operatively connecting the phase lock loop circuit to the USB and Ethernet interfaces to provide a clock signal to the USB and Ethernet interfaces; e) operating the phase lock loop circuit at the USB clock frequency when the USB interface is active; f) operating the phase lock loop circuit at the Ethernet clock frequency when the Ethernet interface is active; g) determining that the USB interface is active when power (VBUS) supplied over the USB interface by the first computer to the printer is present and when a link between the second computer and the printer is not established on the Ethernet interface physical layer (PHY) that controls the signaling rate on the network; and h) determining that the Ethernet interface is active when a link is established between the second computer and the printer on the Ethernet interface PHY before VBUS is present.