Cypress S6J3200 Series, Manual

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CHAPTER 32:Memory Protection Unit for AHB
1164 S6J3200 Series Hardware Manual Document Number: 002-04852 Rev. *G
3.
Operation of the MPU AHB
This section describes the operation of the MPU AHB

MPU AHB Region Granularity and Priority Decision
The MPU AHB supports up to 8 regions and provides the start and end addresses for each of these eight
regions. MPU AHB regions are defined with a granularity of 32 bytes.
Each region is identified as Region 1, Region 2, Region 3 and so on up to Region 8, which is given
highest priority. Region 7 has second highest priority and so on down to Region 1, which has the second
lowest priority. The Background Region is designated the lowest priority region.
The Start Address specifies the first address of the region and is specified by registers MPUHn_SADDR1
to MPUHn_SADDR8 for region 1 to region 8 respectively. Since the region granularity is 32 bytes, the
least significant 5 bits of the start addresses will read 0.
End Addresses are specified by registers MPUHn_EADDR1 to MPUHn_EADDR8n for region 1 to region
8 respectively. The least significant 5 bits of the End Address registers are read only bits and will always
read 1. This ensures the granularity of 32 bytes.
In the MPU AHB, regions may overlap each other, as shown in Figure 3-1. Hence it is also possible that
an AHB address for any transfer may match with multiple regions. Whenever the AHB Transfer Address
matches with multiple regions, the permissions corresponding to the highest priority region (among all
matching regions) is applied.