Nios II Classic Processor Reference Guide

ID 683620
Date 10/28/2016
Document Table of Contents The exception Register

When the extra exception information option is enabled, the Nios II processor provides information useful to system software for exception processing in the exception and badaddr registers when an exception occurs. When your system contains an MMU or MPU, the extra exception information is always enabled. When no MMU or MPU is present, the Nios® II Processor parameter editor gives you the option to have the processor provide the extra exception information.

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

Table 17.  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 18.  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 extra exception information