ST STM32H7 Series User Manual

The Cortex-M4 processor PM0214
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2.4.2 Fault escalation and hard faults
All faults exceptions except for hard fault have configurable exception priority, as described
in System handler priority registers (SHPRx) on page 233. Software can disable execution
of the handlers for these faults, as described in System handler control and state register
(SHCSR) on page 235.
Usually, the exception priority, together with the values of the exception mask registers,
determines whether the processor enters the fault handler, and whether a fault handler can
preempt another fault handler, as described in Section 2.3: Exception model on page 37.
In some situations, a fault with configurable priority is treated as a hard fault. This is called
priority escalation, and the fault is described as escalated to hard fault. Escalation to hard
fault occurs when:
• A fault handler causes the same kind of fault as the one it is servicing. This escalation
to hard fault occurs when a fault handler cannot preempt itself because it must have
the same priority as the current priority level.
• A fault handler causes a fault with the same or lower priority as the fault it is servicing.
This is because the handler for the new fault cannot preempt the currently executing
fault handler.
• An exception handler causes a fault for which the priority is the same as or lower than
the currently executing exception.
• A fault occurs and the handler for that fault is not enabled.
If a bus fault occurs during a stack push when entering a bus fault handler, the bus fault
does not escalate to a hard fault. This means that if a corrupted stack causes a fault, the
fault handler executes even though the stack push for the handler failed. The fault handler
operates but the stack contents are corrupted.
Only Reset and NMI can preempt the fixed priority hard fault. A hard fault can preempt any
exception other than Reset, NMI, or another hard fault.

ST STM32H7 Series Specifications

General

Brand	ST
Model	STM32H7 Series
Category	Computer Hardware
Language	English

Summary

About this document

Typographical Conventions

Defines formatting used in the document for clarity.

List of Abbreviations for Registers

Provides a list of abbreviations used in register descriptions for quick reference.

STM32 Cortex-M4 Processor Overview

Introduces the STM32 Cortex-M4 processor's architecture and key features.

The Cortex-M4 Processor

Programmer's Model

Describes registers, modes, and privilege levels for software execution.

Memory Model

Details the processor's memory map, access behavior, and bit-banding features.

Exception Model

Explains exception states, types, priorities, and handling mechanisms.

Fault Handling

Covers fault types, escalation, status registers, and lockup conditions.

Power Management

Describes mechanisms for entering and exiting low-power sleep modes.

The STM32 Cortex-M4 Instruction Set

Instruction Set Summary

Lists supported Cortex-M4 instructions and their organization.

Memory Access Instructions

Details instructions for loading and storing data from/to memory.

General Data Processing Instructions

Explains instructions for arithmetic, logical, and data manipulation.

Multiply and Divide Instructions

Describes instructions for multiplication and division operations.

Floating-Point Instructions

Details instructions for FPU operations, including VFPv4-SP extension.

Miscellaneous Instructions

Covers instructions like breakpoints, barriers, and supervisor calls.

Core Peripherals

About the STM32 Cortex-M4 Core Peripherals

Introduces the core peripherals accessible via the Private Peripheral Bus (PPB).

Memory Protection Unit (MPU)

Explains the MPU for memory region definition and access control.

Nested Vectored Interrupt Controller (NVIC)

Describes the NVIC for managing interrupts and exceptions with priority levels.

System Control Block (SCB)

Details registers for system control, configuration, and exception reporting.

SysTick Timer (STK)

Explains the 24-bit SysTick timer for system timing and RTOS ticks.

Floating Point Unit (FPU)

Describes the FPU for single-precision floating-point operations.

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