| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a USB interface for a device which establishes communication surely immediately after bus reset release even if a host issues a bus reset signal immediately after 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. When power of the device is turned on, a CPU 3 of the device and the USB controller 1 are initialized. During this initialization, the USB controller 1 keeps the switching element Q1 off as an initial state to generate a quasi power-off state to the host. Then, when the initialization of the USB controller 1 is completed, the USB controller 1 turns on the switching element Q1 to pull up the signal line D+. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
