Qsys System Design Tutorial

ID 683378
Date 5/04/2015
Public
Document Table of Contents

1.5.1.3. Add Memory Master Components

Memory masters access the SDRAM controller by writing the test pattern to the memory and reading the pattern back for validation. The RAM test controller accepts commands from the processor and controls the memory masters. Each command contains a start address, test length in bytes, and memory block size in bytes. The RAM test controller segments the commands into smaller block transfers and issues the commands to the read and write masters independently via streaming connections.

When the pattern reader or writer components complete a block transfer, they signal to the RAM test controller that they are ready for another command. The RAM test controller issues the block-sized commands independently, which minimizes the number of idle cycles between memory transfers. The RAM test controller also ensures that the pattern reader never overtakes the pattern writer with respect to the memory locations it is testing, otherwise data corruption occurs.

The SDRAM controller is parameterized to use a local maximum burst length of 2. The pattern reader and writer components are also configured to match this burst length to maximize the memory bandwidth.