Arbitration circuit for arbitrating requests from multiple processors

摘要

A round robin arbitration circuit arbitrating N requests has a register storing one of N values, a priority encoder selecting one of N priority patterns according to the value in the register and assigning priorities to the requests based on the selected priority pattern, thereby conducting arbitration between the requests, a circuit updating the value in the register among the N values in a predetermined order synchronously with the arbitration, and a circuit updating the value in the register among the N values in the predetermined order at regular intervals that are asynchronous with the arbitration. At the regular intervals that are asynchronous with the arbitration, a jump is made in the predetermined updating order of the values to be set in the register. Accordingly, even if live-lock occurs, it will be solved when such a jump is made to make the number of priority patterns disagree with the number of requests issued in a loop.