ATSAM3U-EK Atmel, ATSAM3U-EK Datasheet - Page 212

• Manufacturer Part Number: ATSAM3U-EK
• Description: KIT EVAL FOR AT91SAM3U CORTEX
• Manufacturer: Atmel
• Type: MCUr

Specifications of ATSAM3U-EK

• Contents: Board
• Processor To Be Evaluated: SAM3U
• Data Bus Width: 32 bit
• Interface Type: RS-232, USB
• Operating Supply Voltage: 3 V
• Silicon Manufacturer: Atmel
• Core Architecture: ARM
• Core Sub-architecture: Cortex - M3
• Silicon Core Number: SAM3U4E
• Silicon Family Name: SAM3U
• Kit Contents: Board CD Docs
• Rohs Compliant: Yes
• For Use With/related Products: AT91SAM3U
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

13.22 Memory protection unit
212
SAM3U Series
This section describes the Memory protection unit (MPU).
The MPU divides the memory map into a number of regions, and defines the location, size,
access permissions, and memory attributes of each region. It supports:
The memory attributes affect the behavior of memory accesses to the region. The Cortex-M3
MPU defines:
When memory regions overlap, a memory access is affected by the attributes of the region with
the highest number. For example, the attributes for region 7 take precedence over the attributes
of any region that overlaps region 7.
The background region has the same memory access attributes as the default memory map, but
is accessible from privileged software only.
The Cortex-M3 MPU memory map is unified. This means instruction accesses and data
accesses have same region settings.
If a program accesses a memory location that is prohibited by the MPU, the processor generates
a memory management fault. This causes a fault exception, and might cause termination of the
process in an OS environment.
In an OS environment, the kernel can update the MPU region setting dynamically based on the
process to be executed. Typically, an embedded OS uses the MPU for memory protection.
Configuration of MPU regions is based on memory types, see
butes” on page
Table 13-34
behavior attributes that are not relevant to most microcontroller implementations. See
configuration for a microcontroller” on page 225
implementation.
Table 13-34. Memory attributes summary
Memory
type
Strongly-
ordered
Device
• independent attribute settings for each region
• overlapping regions
• export of memory attributes to the system.
• eight separate memory regions, 0-7
• a background region.
Shareability
-
Shared
shows the possible MPU region attributes. These include Share ability and cache
70.
Other attributes
-
-
Description
All accesses to Strongly-ordered memory occur
in program order. All Strongly-ordered regions
are assumed to be shared.
Memory-mapped peripherals that several
processors share.
for guidelines for programming such an
“Memory regions, types and attri-
6430D–ATARM–25-Mar-11
“MPU