Frommer Lawrence & Haug LLP
Method and apparatus for transmitting data over data bus at maximum speed
A method and apparatus for transmitting data among devices connected to a serial data bus at maximum speeds are disclosed. Each device may be capable of transmitting data at several speeds. A transmitting device first transmits a data packet to a target recipient device at a maximum transmission speed of the transmitting device. If an acknowledgement signal confirming receipt of the initial data transmission is received from the target recipient, then the transmission speed for subsequent data packet transmissions's set to the speed of the just-transmitted data. Otherwise, the transmission speed is reduced and the process is repeated. Once an acknowledgement is received and the speed is set, the speed may be stored in a memory of the transmitting device for use in future communications with the recipient device. The process is repeated to establish maximum suitable transmission speeds to other target devices connected to the bus. The invention has particular utility when used in conjunction with an IEEE 1394 serial bus interface in the absence of a bus manager. Following a bus reset operation in which the memory of each device is cleared, individual devices reestablish appropriate data transmission speeds to each of the other devices by transmitting packets at varying speeds, if necessary, until acknowledgements are received.
Sony Corporation
H H Y
H04L H04L Y02D
inventional inventional additional
Junji Takehiko
Kato Nakano