Using Nios II Tightly Coupled Memory
Tutorial
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Contents
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July 2005
About This Tutorial............................................................ V
How to Find Information.................................................................................... v
How to Contact Altera ........................................................................................ vi
Typographical Conventions............................................................................... vii
Using Tightly Coupled Memory ............................................. 9
Introduction .......................................................................................................... 9
Reasons for Using Tightly Coupled Memory ......................................... 9
Trade Offs...................................................................................................... 10
Guidelines for Using Tightly Coupled Memory............................................. 10
Hardware Guidelines.................................................................................. 10
Software Guidelines .................................................................................... 11
Locating Functions in Tightly Coupled Memory........................... 11
Tightly Coupled Memory Interface .................................................................. 12
Restrictions.................................................................................................... 12
Dual Port Memories .................................................................................... 13
Building a Nios II System with Tightly Coupled Memory........................... 13
Hardware and Software Requirements.................................................... 14
Modify the Example Design to Include Tightly Coupled Memories.. 15
Create the Tightly Coupled Memories..................................................... 17
Connect & Position the Tightly Coupled Memories.............................. 21
Exception Address Selection...................................................................... 23
Add a Performance Counter ...................................................................... 24
Build the Hardware System ....................................................................... 25
Create a Software Project to Exercise Tightly Coupled Memories...... 26
Specify a Separate Exception Stack........................................................... 26
Change the Projects’ Build Properties ...................................................... 28
Executing the Software on the Modified Standard_tcm Hardware Design 28
Download and Run Tcm_vs_cache Project ............................................. 29
Interrupt Response Time ............................................................................ 29
Memory Access Times ................................................................................ 30
Software Example Implementation Notes....................................................... 30
Checksum Memory Block Size .................................................................. 30
Heating the Instruction Cache ................................................................... 31
Unrolled Checksum Loops for Optimization.......................................... 31
Conclusion............................................................................................................. 31
Contents
iv Altera Corporation
Using Nios II Tightly Coupled Memory Tutorial July 2005
About This Tutorial
Altera Corporation v
July 2005
This tutorial describes how to use tightly coupled memory in Nios
®
II
designs.
The following table shows the revision history of this document.
Date Description
July 2005 First publication.
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