| 摘要 |
PROBLEM TO BE SOLVED: To smoothly issue a transaction that each node could not issue on a bus by monitoring the acquisition state of the bus of its node and converting it to a transaction having higher bus acquisition priority when the bus can not be obtained. SOLUTION: Arbitration control parts 6 and 7 inform a timer control part that their nodes obtain a bus by using a signal line 17 in such a case. A timer control part clears a timer to zero. Consequently, when the bus can not be acquired, a timer is made to count up. a comparison part always compares the value of the timer with a time-out setting register and when it matches the value of the time-out setting register, a signal line 18 informs request control parts 2 and 3 of that. The request control parts 2 and 3 recognize that their transactions can not be issued to the bus and converts the request priority levels of the transactions to higher priority, thereby sending a request to all nodes.
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