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US 7,254,662 B2Granted
Data link layer device for a serial communication bus
AssigneeThomas Licensing
InventorsTimothy Heighway, Klaus Gaedke, Siegfried Schweidler
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AssigneeThomas Licensing
InventorsTimothy Heighway, Klaus Gaedke, Siegfried Schweidler
Estimating the term…
According to the IEEE1394 bus protocol, priority is given to isochronous data packets. Data transfer is done in transfer cycles under the control of a cycle master. It depends on the allocated bandwidth for isochronous data how much transport capacity is available in a transfer cycle. To managed the mixed data transfer in one cycle it is specified that the bus nodes not having isochronous data to transfer need to wait with their transmission requests until the end of the isochronous data transfers in the cycle indicated with a sub-action gap. The invention aims to improve the efficiency of data transport for the case that none of the bus nodes need to transfer isochronous data. The data link layer devices according to the invention includes means for checking whether isochronous data is to be transferred and if not they switch over to a no cycle master state, in which the local cycle synchronization events are ignored. The nodes need not wait for a sub-action gap after a local cycle event before drawing asynchronous transmission requests.
Data link layer device for a serial communication bus comprising an interface to a physical layer unit and an interface to at least one host processor supporting the higher layers of the OSI/ISO data communication reference model, wherein, the data link layer device further comprises means for checking whether a cycle master capable of transmitting a cycle start packet for isochronous and asynchronous data transmissions over the serial communication bus exists in the network, comprising
Dependencies are inferred from the claim text.