| 摘要 |
An arbitration unit contains a method of arbitration which includes distributed arbitration, a priority mechanism to support different classes o f traffic, a unique arbitration ID bits for each module, a round robin arbitration within a given priority level to produce fair access to a bus (36), an arbitration timeout, and a bandwidth allocation between priority levels. The method of round robin bus arbitration includes the steps of providing a plurality of modules, providing a bus having a plurality of data lines, the bus connecting the plurality of modules, the bus having an arbitration unit, setting the bus to a wait state, signaling a first bus request to the bus by a first module needing to transmit a first plurality o f data packets onto the bus, the first module having a first module priority level and a first unique arbitration number, signaling a second bus request to the bus by a second module needing to transmit a second plurality of data packets onto the bus, the second module having a second module priority leve l and a second unique arbitration number, establishing a bus priority accordin g to a comparison of the first module priority level and the second module priority level, asserting the first unique arbitration number on the bus by the first module, asserting the second unique arbitration number on the bus by the second module, determining whether the first module and the second modul e have been waiting for the bus, comparing the first unique arbitration number and the second unique arbitration number, scheduling transmission of data packets in response to the steps of determining and comparing, and repeating the steps of setting, signaling, establishing, asserting, determining, comparing, and scheduling.
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