Embedded Design Handbook

ID 683689
Date 8/28/2023
Public
Document Table of Contents

7.5.3.1. Hardware Guidelines

The following guidelines apply to Nios® II hardware designs that include tightly coupled memory:

  • Tightly coupled masters are presented as additional master ports on the Nios® II processor.
  • An On-Chip Memory component is the only memory that can connect to a tightly coupled master port on the Nios® II core.
  • A tightly coupled master on a processor must connect to exactly one on-chip memory slave port. This slave port cannot be shared by any other master port.
  • Each on-chip memory can be connected to only one tightly coupled master even if it is a dual port memory.
  • The availability of the data and instruction master ports for the tightly coupled memory is dependent on the type of Nios® II core used.
  • When using the On-Chip Memory component as a tightly coupled memory for Nios® II, you must always create it as a RAM, not as a ROM. Tightly coupled memories configured as ROM would result in failure.
  • To conserve the logic elements, use one 2-kilobyte (KB) tightly coupled memory, rather than two 1-KB tightly coupled memories.

The figure below is a block diagram of a simple Nios® II system that includes tightly coupled memories and other Platform Designer System Integration Tool components.

Figure 280.  Nios® II System with Tightly Coupled Instruction and Data Memory