Data link layer device for a serial communication bus
US7254662B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 17, 2003 |
| Grant date | Aug 7, 2007 |
| Priority date | — |
| Expiry date | Jun 17, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L69/18
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.