PXD20RM Datasheet, PDF (1047/1628 Pages) Freescale Semiconductor, Inc – PXD20 Microcontroller

The region descriptors are organized sequentially in the MPU’s programming model and each of the four
32-bit words are detailed in the subsequent sections.
28.2.2.4.1 MPU Region Descriptor n, Word 0 (MPU_RGDn.Word0)
The first word of the MPU region descriptor defines the 0-modulo-32 byte start address of the memory
region. Writes to this word clear the region descriptor’s valid bit (see Section 28.2.2.4.4, MPU Region
Descriptor n, Word 3 (MPU_RGDn.Word3) for more information).
Offset MPU_Base + 0x400 + (16*n) + 0x0 (MPU_RGDn.Word0)
Access: R/W
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
R
SRTADDR
00000
W
Reset _{- - - - - - - - - - - - - - - - - - - - - - - - - - - 0 0 0 0 0}
Figure 28-5. MPU Region Descriptor, Word 0 Register (MPU_RGDn.Word0)
Table 28-5. MPU_RGDn.Word0 Field Descriptions
Field
Description
0–26 Start Address. This field defines the most significant bits of the 0-modulo-32 byte start address of the
SRTADDR memory region.
28.2.2.4.2 MPU Region Descriptor n, Word 1 (MPU_RGDn.Word1)
The second word of the MPU region descriptor defines the 31-modulo-32 byte end address of the memory
region. Writes to this word clear the region descriptor’s valid bit (see Section 28.2.2.4.4, MPU Region
Descriptor n, Word 3 (MPU_RGDn.Word3) for more information).
Offset MPU_Base + 0x400 + (16*n) + 0x4 (MPU_RGDn.Word1)
Access: R/W
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
R
ENDADDR
11111
W
Reset _{- - - - - - - - - - - - - - - - - - - - - - - - - - - 1 1 1 1 1}
Figure 28-6. MPU Region Descriptor, Word 1 Register (MPU_RGDn.Word1)
Table 28-6. MPU_RGDn.Word1 Field Descriptions
Field
Description
0–26 End Address. This field defines the most significant bits of the 31-modulo-32 byte end address of the
ENDADDR memory region. There are no hardware checks to verify that ENDADDR >= SRTADDR; it is software’s
responsibility to properly load these region descriptor fields.
Freescale Semiconductor
PXD20 Microcontroller Reference Manual, Rev. 1
Preliminary—Subject to Change Without Notice
28-9