Intel® Quartus® Prime Pro Edition User Guide: Platform Designer

ID 683609
Date 10/04/2021
Public

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5.1.5.2. Fixed Priority Arbitration

Fixed priority arbitration is an alternative arbitration scheme to the default round-robin scheme.

You can selectively apply fixed priority arbitration to any agent in a Platform Designer system. You can design Platform Designer systems where a subset of agents use the default round-robin arbitration, and other agents use fixed priority arbitration. Fixed priority arbitration uses a fixed priority algorithm to grant access to an agent amongst its connected hosts.

Set a fixed priority agent arbitration under Interconnect Parameters in the Domains tab. You can then assign an arbitration priority number for each host connected to a fixed priority agent in the System View tab, where the highest numeric value receives the highest priority. When multiple hosts request access to a fixed priority arbitrated agent, the arbiter gives the host with the highest priority first access to the agent.

For example, when a fixed priority agent receives requests from three hosts on the same cycle, the arbiter grants the host with highest assigned priority first access to the agent, and backpressures the other two hosts.

Note: When you connect an AXI master to an Avalon® memory mapped agent designated to use a fixed priority arbitrator, the interconnect instantiates a command-path intermediary round-robin multiplexer in front of the designated agent.