| 摘要 |
A four-phase arbitration system employs a master and a slave arbiter. The master arbiter operates to provide ownership of a bus to a first device if a second device, coupled to the slave arbiter is not conducting a transaction. If the second device desires use of the bus, the slave arbiter sends a request to the master arbiter, which asserts an acknowledge signal for as long as the first device has ownership of the bus, and at least as long as a timeout of the first device. The master arbiter de-asserts its acknowledge signal when the first device ceases ownership of the bus. The slave arbiter is responsive to the de-assertion of the acknowledge signal to assert bus ownership to the second device. When the second device transaction is completed, its request signal is de-asserted to the master arbiter, causing the master arbiter to re-assert the acknowledge signal. Failure to receive a de-asserted acknowledge signal causes the slave arbiter to move to the next state.
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