Communication apparatus and method for communicating with an external device through USB interface using a high-speed or low-speed communication mode

A communication apparatus that communicates with an external device using a high-speed communication mode or a low-speed communication mode, the communication apparatus comprising:

• a communication speed control unit configured to initially set a communication mode to the low-speed communication mode as a default condition so as to reduce power consumption;
• a speed requirement detecting unit configured to determine, upon connection of the external device with the communication apparatus, if the high-speed communication mode is required for communication with the external device based on a total of multiple data transfer rates requested by the external device;
• wherein, if the speed requirement detecting unit determines that the high-speed communication mode is required and the current communication mode is the low-speed communication mode, the communication speed control unit changes the communication mode to the high-speed communication mode, where upon completion of all data transfers, the communication speed control unit is configured to return the communication mode to the low-speed communication mode as the default condition;
• and
• wherein the communication speed control unit returns the communication mode to the low-speed communication mode if an isochronous transfer is not currently executing and a total of data transfer rates requested by the data transfers currently executing is equal to or lower than the data transfer rate which can be provided by the low speed communication mode.

A method for communication between a communication apparatus and an external device, the method utilizing a high-speed communication mode or a low-speed communication mode, the method comprising:

• initially setting a communication mode, by a communication speed control unit, to the low-speed communication mode as a default condition so as to reduce power consumption;
• determining, by a speed requirement detecting unit, upon connection of the external device with the communication apparatus, if the high-speed communication mode is required for communication with the external device;
• changing the communication mode to the high-speed communication mode, by the communication speed control unit, prior to a data transfer with the external device, if the speed requirement detection unit determines that the high-speed communication mode is required;
• upon completion of the data transfer, returning the communication mode to the low-speed communication mode, by the communication speed control unit as the default condition;
• and
• returning the communication mode to the low-speed communication mode if an isochronous transfer is not currently executing and a total of data transfer rates requested by the data transfers currently executing is equal to or lower than the data transfer rate which can be provided by the low speed communication mode.