| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a USB interface for a device which allows communication to be performed immediately after bus reset release even if a host issues a bus reset signal immediately on detection of power-on of the device. <P>SOLUTION: A USB controller 1 is so configured that pull-up of a signal line D+ for informing the host of power-on of the device can be controlled through a switching element Q1. In response to power-on of the device, a CPU 3 of the device initializes itself and the USB controller 1. During this initialization, the USB controller 1 keeps the switching element Q1 in a turned-off state being an initial state to create a quasi power-off state to the host. After the completion of initialization of the USB controller 1, the USB controller 1 turns on the switching element Q1 to pull up the signal line D+. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
