Nios® II Processor Reference Guide

ID 683836
Date 8/28/2023
Document Table of Contents The exception Register

Nios® II/f Processor provides information useful to system software for exception processing in the exception and badaddr registers when an exception occurs.

Note: The exception register is not available for Nios® II/e core, therefore you cannot add a MMU or MPU to the processor configuration. For more information, refer to the Nios® II Core Implementation Details chapter of this document.

For information about controlling the extra exception information option, refer to the Instantiating the Nios® II Processor chapter of this document.

Table 15.  exception Control Register Fields
Bit Fields
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
ECCFTL Reserved
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Reserved Cause Rsvd
Table 16.  exception Control Register Field Descriptions
Field Description Access Reset Available
ECCFTL The Nios® II processor writes to ECCFTL when it detects a potentially fatal ECC error. When ECCFTL = 1, the Nios® II processor detects an ECC register file error. When ECCFTL = 0, another ECC exception occurred. Read 0 Only with ECC
CAUSE CAUSE is written by the Nios® II processor when certain exceptions occur. CAUSE contains a code for the highest-priority exception occurring at the time. The Cause column in the Nios II Exceptions (In Decreasing Priority Order table lists the CAUSE field value for each exception.

CAUSE is not written on a break or an external interrupt.

Read 0 Only with Nios® II/f