| 摘要 |
The invention relates to universal serial bus (USB) circuits utilised in USB devices and USB hubs. Specifically, the invention relates to circuitry used to detect whether the hub or device is connected to a USB host, i.e. to detect connection status of the device or hub. The present invention provides a USB circuit comprising a microprocessor adapted to receive signalling concerning the connection status of the USB circuit to a USB host circuit, first and second data signal lines adapted to transmit respective first and second data signals to the microprocessor, a USB host power supply signal line adapted to receive USB host power signalling to indicate connection status, and wherein the USB circuit is characterised by comprising connection status signalling means adapted to analyze the USB power supply signal line and change the data signal transmitted down the first and second data lines according to the connection status of USB circuit to the USB host circuit.
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