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Chapter 17 Memory Protection Unit (S12XMPUV2)
MC9S12XF - Family Reference Manual, Rev.1.19
810
Freescale Semiconductor
17.3.1.9
MPU Descriptor Register 3 (MPUDESC3)
Figure 17-11. MPU Descriptor Register 3 (MPUDESC3)
Read: Anytime
Write: Anytime
Table 17-11. MPUDESC3 Field Descriptions
17.3.1.10 MPU Descriptor Register 4 (MPUDESC4)
Figure 17-12. MPU Descriptor Register 4 (MPUDESC4)
Read: Anytime
Write: Anytime
Table 17-12. MPUDESC4 Field Descriptions
Address: Module Base + 0x0009
76543210
R
WP
NEX
00
HIGH_ADDR[22:19]
W
Reset
0
1(1)
1. These bits are intialized to the upper boundary of the MPU address range by a system reset. Depending on dened descriptor
granularity and MPU address range some of these bits may not be writeable.
Field
Description
7
WP
Write-Protect bit — The WP bit causes the described memory range to be treated as write-protected. If this
bit is set every attempt to write in the described memory range causes an access violation.
6
NEX
No-Execute bit — The NEX bit prevents the described memory range from being used as code memory. If this
bit is set every Op-code fetch in this memory range causes an access violation.
3–0
HIGH_ADDR[
22:19]
Memory range upper boundary address bits — The HIGH_ADDR[22:19] bits represent bits [22:19] of the
global memory address that is used as the upper boundary for the described memory range.These bits are
intialized to the upper boundary of the MPU address range by a system reset.
Address: Module Base + 0x000A
76543210
R
HIGH_ADDR[18:11]
W
Reset
1(1)
1. These bits are intialized to the upper boundary of the MPU address range by a system reset. Depending on dened descriptor
granularity and MPU address range some of these bits may not be writeable.
Field
Description
7–0
HIGH_ADDR[
18:11]
Memory range upper boundary address bits — The HIGH_ADDR[18:11] bits represent bits [18:11] of the
global memory address that is used as the upper boundary for the described memory range. These bits are
intialized to the upper boundary of the MPU address range by a system reset.