External Memory Interface Handbook Volume 3: Reference Material: For UniPHY-based Device Families

ID 683841
Date 3/06/2023
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5.2.4. Arbiter

The arbiter determines the order in which requests are passed to the memory device. When the arbiter receives a single request, that request is passed immediately; however, when multiple requests are received, the arbiter uses arbitration rules to determine the order in which to pass requests to the memory device.

Arbitration Rules

The arbiter uses the following arbitration rules:

  • If only one master is issuing a request, grant that request immediately.
  • If there are outstanding requests from two or more masters, the arbiter applies the following tests, in order:
  • Is there a read request? If so, the arbiter grants the read request ahead of any write requests.
  • If neither of the above conditions apply, the arbiter grants the oldest request first.