Root repeater, USB communication system, USB communication control method

摘要

A controller resets a whole bus and enters connection waiting state upon detecting disconnection of a USB device, registers all connected USB devices by giving sequential addresses beginning from a predetermined value, communicates with each of registered USB devices, and responsive to a response from the USB device, sequentially broadcasts data to all the registered USB devices or transmits the data to a particular USB device. A bus configuration register registers one of three device types including a hub, USB device, and others based on a device address, wherein the bus configuration register is cleared when said controller enters the connection waiting state. A pattern determination unit, responsive to detection of connection of a USB device, determines whether or not the connected device is the supporting device based on whether or not a predetermined portion of a configuration descriptor of the connected device matches a predetermined pattern.