Ashling* RiscFree* Integrated Development Environment (IDE) for Altera® FPGAs User Guide

ID 730783
Date 4/11/2025
Public
Document Table of Contents

2.3.4.3. Considerations when Debugging ROM-based Designs

A ROM-based Nios® V processor design refers to the Nios® V processor software developed specifically to be stored in involatile memories, such as ROM or Flash. The ROM-based designs are closely related to the booting implementation in Nios® V Embedded Processor Design Handbook.
  • Nios® V Processor Booting from On-Chip Flash (UFM)
  • Nios® V Processor Booting from General Purpose QSPI Flash
  • Nios® V Processor Booting from Configuration QSPI Flash
  • Nios® V Processor Booting from On-Chip Read-Only Memory (OCROM

Any write attempt by the debugger into a ROM or Flash is not supported because of the ROM’s read-only characteristics and the Flash’s write operation complexity, respectively.

Thus, debugging ROM-based designs come with the following limitations:
  1. The debugger is unable to download the application ELF into ROM/Flash. This is affecting the Load Image feature in Startup tab.
  2. The debugger is unable to set software breakpoint, which replaces instructions with ebreak. This condition is affecting the Set breakpoint at feature in Startup tab, stepping actions in Debug Bar and Toggle Breakpoint.

Once the application is booting successfully, Altera recommends implementing Connect to a Running Nios V Processor Application along with setups in Unable to Set Software Breakpoint to connect and debug the application.