ST STM32H7 Series User Manual

PM0214 Rev 9 29/262
PM0214 The Cortex-M4 processor
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2.2.1 Memory regions, types and attributes
The memory map and the programming of the MPU splits the memory map into regions.
Each region has a defined memory type, and some regions have additional memory
attributes. The memory type and attributes determine the behavior of accesses to the
region.
The memory types are:
The different ordering requirements for Device and Strongly-ordered memory mean that the
memory system can buffer a write to Device memory, but must not buffer a write to Strongly-
ordered memory.
The additional memory attributes include:
2.2.2 Memory system ordering of memory accesses
For most memory accesses caused by explicit memory access instructions, the memory
system does not guarantee that the order, in which the accesses complete, matches the
program order of the instructions, providing this does not affect the behavior of the
instruction sequence. Normally, if correct program execution depends on two memory
accesses completing in program order, software must insert a memory barrier instruction
between the memory access instructions, see Section 2.2.4: Software ordering of memory
accesses on page 31.
However, the memory system does guarantee some ordering of accesses to Device and
Strongly-ordered memory. For two memory access instructions A1 and A2, if A1 occurs
before A2 in program order, the ordering of the memory accesses caused by two
instructions is:
Normal The processor can re-order transactions for efficiency, or
perform speculative reads.
Device The processor preserves transaction order relative to other
transactions to Device or Strongly-ordered memory.
Strongly-ordered The processor preserves transaction order relative to all other
transactions.
Execute Never (XN) Means that the processor prevents instruction accesses. Any
attempt to fetch an instruction from an XN region causes a
memory management fault exception.
Table 12. Ordering of memory accesses
(1)
1. - means that the memory system does not guarantee the ordering of the accesses.
< means that accesses are observed in program order, that is, A1 is always observed before A2.
A1
A2
Normal access
Device access Strongly
ordered
access
Non-shareable Shareable
Normal access - - - -
Device access, non-shareable - < - <
Device access, shareable - - < <
Strongly ordered access - < < <

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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