arbitration of interconnect

[CHung]

Hi,

In figure 45 of below website, there are some arbiters.

https://www.intel.com/content/www/us/en/programmable/documentation/jrw1529444674987.html

I'm not familiar with Quartus IP, and cannot find the arbiter in Quartus IP Catalog.

How to generate the arbiter when we have multiple master?

And is there any parameters to adjust the arbitration algorithm?

e.g. round-robin or some master has high priority.

Thanks.

[RichardTanSY_Intel]

When multiple masters contend for access to a slave, Platform Designer automatically inserts arbitration logic, which grants access in fairness-based, round-robin order. You can alternatively choose to designate a slave as a fixed priority arbitration slave, and then manually assign priorities in the Platform Designer GUI.

Reference: https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/ug/ug-qps-platform-designer.pdf#page=136

You can also check Figure 86 on 'Arbitration Shares in the Connection Column'.

[CHung]

OK.

Thank you.

[anonimcs]

@RichardTanSY_Intel I have a question regarding the arbitration of the Platform Designer. Say I want a system that module X and the Nios2 core are the two masters of a slave B. I want to have the Nios2 to make the initial configurations etc on slave B but then I want slave B to obey the master X for almost the rest of the time. The Master X is also a slave of Nios2, but I'd like to use the Avalon bus for the data transfer between Master X and slave B. How should I set the arbitration in the Platform Designer then ? I can already choose "Fixed Priority" but then how does it switch between two masters in this case ?

[sstrell]

(Intel uses "host" and "agent" now instead of "master" and "slave".)

It doesn't sound like you need to do anything other than make the connections.  Nios will initially have access to B when needed and then X will have access since the Nios is not accessing it.  Arbitration is only an issue if multiple hosts are accessing a single agent at the same time.

If you are saying that Nios and X may access B at the same time, then you can adjust the arbitration shares for one or the other to give higher priority or switch to the fixed arbitration scheme mentioned.