Nios® V Embedded Processor Design Handbook

ID 726952
Date 12/09/2025
Public
Document Table of Contents

2.1.1.2.5. ECC Tab

Table 13.  ECC Tab
ECC Description
Enable Error Detection and Status Reporting Enable this option to apply the following ECC feature for Nios® V processor internal RAM blocks.
  • ECC Detection
  • ECC Status Reporting
  • Single-Bit Correction without Writeback
Enable Single Bit Correction Enable this option to apply the following ECC feature for Nios® V processor internal RAM blocks.
  • ECC Injection
  • ECC Exception Code
Note: You must enable Error Detection and Status Reporting to use this feature.

Refer to Nios® V Processor Reference Manual for more information about each ECC features.

Table 14.  ECC Reaction based on Settings
ECC Events Enable Error Detection and Status Reporting Enable Error Detection and Status Reporting

&

Enable Single Bit Correction

Single-bit ECC Error
  • The error is correctable.
  • Processor continues to operate after correcting the error in the processor pipeline.
  • However, the correction is not written back into the source memories.
  • The error is correctable.
  • Processor continues to operate after correcting the error in the processor pipeline.
  • Optionally, you can implement an ECC exception handler to writeback into the source memories.1
Double-bit ECC Error
  • The error is uncorrectable.
  • Processor continues to operate without correcting it in the processor pipeline, which might cause the processor to enter a nondeterministic state (stalling).
  • No correction to write back into the source memories.
  • The error is uncorrectable.
  • Processor continues to operate without correcting it in the processor pipeline, which might cause the processor to enter a nondeterministic state (stalling).
  • Optionally, you can implement an ECC exception handler to correct and writeback into the source memories to prevent stalling.
1 This option is applicable when you are developing custom processor firmware. The Altera HAL firmware supports its own writeback function for single-bit ECC errors. Refer to Nios® V Software Developer’s Handbook – ECC Handling.