UM10360 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
User manual Rev. 3 — 20 December 2013 747 of 841
NXP Semiconductors
UM10360
Chapter 34: Appendix: Cortex-M3 user guide
A memory management fault is an exception that occurs because of a memory
protection related fault. The MPU or the fixed memory protection constraints
determines this fault, for both instruction and data memory transactions. This fault is
used to abort instruction accesses to Execute Never (XN) memory regions, even if
the MPU is disabled.
• Bus fault
A bus fault is an exception that occurs because of a memory related fault for an
instruction or data memory transaction. This might be from an error detected on a bus
in the memory system.
• Usage fault
A usage fault is an exception that occurs because of a fault related to instruction
execution. This includes:
– an undefined instruction
– an illegal unaligned access
– invalid state on instruction execution
– an error on exception return.
The following can cause a usage fault when the core is configured to report them:
– an unaligned address on word and halfword memory access
– division by zero.
• SVCall
A supervisor call (SVC) is an exception that is triggered by the
SVC
instruction. In an
OS environment, applications can use
SVC
instructions to access OS kernel functions
and device drivers.
• PendSV
PendSV is an interrupt-driven request for system-level service. In an OS environment,
use PendSV for context switching when no other exception is active.
• SysTick
A SysTick exception is an exception the system timer generates when it reaches zero.
Software can also generate a SysTick exception. In an OS environment, the
processor can use this exception as system tick.
• Interrupt (IRQ)
A interrupt, or IRQ, is an exception signalled by a peripheral, or generated by a
software request. All interrupts are asynchronous to instruction execution. In the
system, peripherals use interrupts to communicate with the processor.
Table 639. Properties of the different exception types
Exception
number
[1]
IRQ
number
[1]
Exception
type
Priority Vector address
or offset
[2]
Activation
1 - Reset -3, the highest
0x00000004
Asynchronous
2-14NMI -2
0x00000008
Asynchronous
3-13Hard fault-1
0x0000000C
-
4 -12 Memory
management fault
Configurable
[3]
0x00000010
Synchronous
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