Exception Types; Table 5-1 Exception Types - ARM Cortex-M3 Technical Reference Manual

5.2

Exception types

Exception type
-
Reset
Non-maskable Interrupt
Hard Fault
Memory Management
Bus Fault
Usage Fault
-
SVCall
ARM DDI 0337B
Various types of exceptions exist in the processor. A fault is an exception which results
from an error condition due to instruction execution. Faults can be reported
synchronously or asynchronously to the instruction which caused them. In general,
faults are reported synchronously. The Imprecise BusFault is an asynchronous fault
supported in the ARMv7-M profile. A synchronous fault is always reported with the
instruction which caused the fault. An asynchronous fault does not guarantee how it is
reported with respect to the instruction which caused the fault.
For more information on exceptions see the ARMv7-M Architecture Reference Manual.
Table 5-1 shows the exception types, priority, and position. Position refers to the word
offset from the start of the vector table. The lower numbers shown in the Priority column
of the table are higher priority. Also shown is how the types are activated,
synchronously or asynchronously. The exact meaning and use of priorities is explained
in Exception priority on page 5-5.
Position Priority
0 -
1 -3 (highest)
2 -2
3 -1
4 a
settable
5
b
settable
6 settable
7-10 -
11 settable
Copyright © 2005, 2006 ARM Limited. All rights reserved.
Description
Stack top is loaded from first entry of vector table on reset.
Invoked on power up and warm reset. On first instruction,
drops to lowest priority (Thread Mode). This is asynchronous.
Cannot be stopped or preempted by any exception but reset.
This is asynchronous.
All classes of Fault, when the fault cannot activate because of
priority or the Configurable fault handler has been disabled.
This is synchronous.
MPU mismatch, including access violation and no match. This
is synchronous. This is used even if the MPU is disabled or not
present, to support the XN regions of the default memory map.
Pre-fetch fault, memory access fault, and other
address/memory related. This is synchronous when precise
and asynchronous when imprecise.
Usage fault, such as Undefined instruction executed or illegal
state transition attempt. This is synchronous.
Reserved
System service call with SVC instruction. This is
synchronous.
Exceptions

Table 5-1 Exception types

5-3