Matsushita Electric Industrial Co., Ltd.

Kiyotaka Iwamoto

Takayuki Matsui

Ryougo Yanagisawa

In an interface control semiconductor integrated circuit including a plurality of protocol circuits for processing a protocol such as AV- or PC-oriented protocols engaged in an IEEE 1394 standard-compliant data transmission, power consumption is reduced. To achieve this, the interface control semiconductor integrated circuit including the protocol circuits is provided with a plurality of switches associated with the respective protocol circuits and each of the switches performs a switching between supply and shut-off of a clock. A clock is supplied to one of the protocol circuits which should be used whereas clock to unused protocol circuits are shut-off, by controlling each of the switches.

System for controlling the clock to each of a plurality of protocol circuits of an interface control integrated circuit based on the type of data to be transmitted

In a data transmit/receive method for plurality of devices connected by a 1394 bus, a receiving device obtains a device-specific number of a transmitting device when starting to receive data. When a bus reset occurs, the receiving device again obtains the device-specific number from the transmitting device, and checks whether the device-specific numbers before and after the bus reset match. If the device-specific numbers differ, the receiving device obtains the device-specific number from all devices connected to the bus. If a device with the same device-specific numbers as prior to the bus reset is present among the obtained device-specific numbers, the channel number of the bus used for the transmitting of data is determined, and the receiving device starts receiving with that channel number. Then device authentication with the transmitting device is carried out, and key information for solving the encryption is obtained.

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Osaka, Japan

Kiyotaka Iwamoto