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2.2.3. Behavior of memory accesses

The behavior of accesses to each region in the default memory map is:

Table 2.9. Memory access behavior
Address rangeMemory regionMemory type [a]XN [a]Description

0x00000000- 0x1FFFFFFF

Code

Normal

-Executable region for program code. You can also put data here.

0x20000000- 0x3FFFFFFF

SRAM

Normal

-

Executable region for data. You can also put code here.

0x40000000- 0x5FFFFFFF

Peripheral

Device

XNExternal device memory.

0x60000000- 0x9FFFFFFF

External RAM

Normal

-Executable region for data.

0xA0000000- 0xDFFFFFFF

External device

Device

XNExternal device memory.

0xE0000000- 0xE00FFFFF

Private Peripheral Bus

Strongly- ordered

XN

This region includes the NVIC, System timer, and System Control Block.

Only word accesses can be used in this region.

0xE0100000- 0xFFFFFFFF

SystemDeviceXN

Vendor specific.

[a] See Memory regions, types and attributes for more information.


The Code, SRAM, and external RAM regions can hold programs.

The optional MPU can override the default memory access behavior described in this section. For more information, see Memory Protection Unit.

Additional memory access constraints for caches and shared memory

When a system includes caches or shared memory, some memory regions have additional access constraints, and some regions are subdivided, as Table 2.10 shows:

Table 2.10. Memory region shareability and cache policies
Address rangeMemory regionMemory type [a]Shareability [a]Cache policy [b]

0x00000000- 0x1FFFFFFF

Code

Normal

-WT

0x20000000- 0x3FFFFFFF

SRAM

Normal

-WBWA

0x40000000- 0x5FFFFFFF

Peripheral

Device

--

0x60000000- 0x7FFFFFFF

External RAM

Normal

-WBWA

0x80000000- 0x9FFFFFFF

WT

0xA0000000- 0xBFFFFFFF

External device

Device

Shareable-
0xC0000000- 0xDFFFFFFFNon-shareable

0xE0000000- 0xE00FFFFF

Private Peripheral Bus

Strongly- ordered

Shareable-

0xE0100000- 0xFFFFFFFF

System

Device

--

[a] See Memory regions, types and attributes for more information.

[b] WT = Write through, no write allocate. WBWA = Write back, write allocate.


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