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AR# 56598

LogiCORE IP AXI Crossbar v2.0 - How to set various ID parameters and drive ID signals

Description

There are several parameters used by the crossbar for setting up IDs: ID_WIDTH, THREAD_ID_WIDTH, BASE_ID.
 
What is the difference between these and how do I set them?
 

Solution

THREAD_ID_WIDTH

Should be set as the total number of threads that a given endpoint master device (which is connected to an SI slot) is capable of issuing.
 
 
ID_WIDTH

This is the total internal width of ID signals propagated through the Crossbar switch.

This should be set according to this equation:

ceil_log2(NUM_SI) + max(THREAD_ID_WIDTH).
 
 
BASE_ID

This is the value which the Crossbar assigns to each SI slot as a unique 'Master ID' to help route a request's response back to the SI slot that requested it.

This value is set automatically by the IP GUI and should take up the remaining ID bits between ID_WIDTH-THREAD_ID_WIDTH.
 

Note:
The width of the *ID signals is (ID_WIDTH-1 downto 0).

You must take care that the bits between ID_WIDTH-THREAD_ID_WIDTH are NOT driven, as this can cause incorrect routing of requests and/or responses.
AR# 56598
Date Created 06/26/2013
Last Updated 03/25/2015
Status Active
Type General Article
IP
  • AXI Interconnect