The Definitive Guide to the ARM Cortex-M0

Chapter 12. Fault Handling

Fault Exception Overview

In ARM processors, when a program goes wrong and if the processor detects the fault, a fault exception occurs. On the Cortex-M0 processor, there is only one exception type that handles faults: the hard fault handler.

The hard fault handler is almost the highest priority exception type, with a priority level of −1. Only the Nonmaskable interrupt (NMI) can preempt it. When it is executed, we know that the microcontroller is in trouble and corrective action is needed. The hard fault handler is also useful for debugging during the software development stage. When a breakpoint has been set in the hard fault handler, the program execution stops when a fault occurs. By examining the content of the stack, ...