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

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

4.1.4.3. Avalon® -MM Unaligned Burst Expansion Bridge Example

Figure 115. Unaligned Burst Expansion BridgeThe example below shows an unaligned read burst command from a master that the Avalon® -MM Unaligned Burst Expansion Bridge converts to an aligned request for a connected slave, and the suppression of words due to the aligned read burst command. In this example, a 32-bit master requests an 8-beat burst of 32-bit words from a 64-bit slave with a start address that is not 64-bit aligned.


Because the target slave has a 64-bit data width, address 1 is unaligned in the slave's address space. As a result, several smaller burst transactions are needed to request the data associated with the master's read burst command.

With an Avalon® -MM Unaligned Burst Expansion Bridge in place, the bridge issues a new read burst command to the target slave beginning at address 0 with burst length 10, which requests data up to the word stored at address 9.

When the bridge receives the word corresponding to address 0, it suppresses it from the master, and then delivers the words corresponding to addresses 1 through 8 to the master. When the bridge receives the word corresponding to address 9, it suppresses that word from the master.