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

ID 683364
Date 12/15/2018
Public
Document Table of Contents

3.1.5.2. 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 slave in a Platform Designer system. You can design Platform Designer systems where a subset of slaves use the default round-robin arbitration, and other slaves use fixed priority arbitration. Fixed priority arbitration uses a fixed priority algorithm to grant access to a slave amongst its connected masters.

To set up fixed priority arbitration, you must first designate a fixed priority slave in your Platform Designer system in the Interconnect Requirements tab. You can then assign an arbitration priority number for each master connected to a fixed priority slave in the System View tab, where the highest numeric value receives the highest priority. When multiple masters request access to a fixed priority arbitrated slave, the arbiter gives the master with the highest priority first access to the slave.

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

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