MPC555CME Freescale Semiconductor, MPC555CME Datasheet - Page 390

• Manufacturer Part Number: MPC555CME
• Description: KIT EVALUATION FOR MPC555
• Manufacturer: Freescale Semiconductor
• Type: Microcontrollerr

Specifications of MPC555CME

• Contents: Module Board, Installation Guide, Power Supply, Cable, Software and more
• Processor To Be Evaluated: MPC555
• Data Bus Width: 32 bit
• Interface Type: RS-232
• For Use With/related Products: MPC555
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

11.5 Data Memory Protection
11.5.1 Functional Description
MPC555
USER’S MANUAL
The data memory protection unit (DMPU) in the L2U module provides access protec-
tion for the memory regions on the U-bus side from load/store accesses by the RCPU.
(Only U-bus space is protected.) The DMPU does not protect PowerPC register ac-
cesses initiated by the RCPU on the L-bus. The user can assign up to four regions of
access protection attributes and can assign global attributes to any space not included
in the active regions. When it detects an access violation, the L2U generates an ex-
ception request to the CPU.
Data memory protection is assigned on a regional basis. Default manipulation of the
DMPU is done on a global region. The DMPU has control registers which contain the
following information: region protection on/off, region base address, region size, and
the region’s access permissions. Each region’s protection attributes can be turned on/
off by configuring the enable attribute bit (ENRx) located in the global region attribute
register.
During each load/store access from the RCPU core to the U-bus, the address is com-
pared to the value in the region base address register of each enabled region. Any ac-
cess that matches the specific region within its appropriate size, as defined by the
region size field (RS) of the region attribute register, sets a match indication.
Region0 Address and size
Region1 Address and size
Region2 Address and size
Region3 Address and size
/
MPC556
Address
Figure 11-2 DMP Basic Functional Diagram
L-BUS TO U-BUS INTERFACE (L2U)
Rev. 15 October 2000
Match
select
Region
MSR
Region0 protection/attribute
Region1 protection/attribute
Region2 protection/attribute
Region3 protection/attribute
Global protection/attribute
Protection/Attribute
DR
Access attribute
GRANTED
ACCESS
Error Interrupts
Exception
Logic
Specific
to Core
MOTOROLA
11-4