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415
11100B–ATARM–31-Jul-12
SAM4S Series [Preliminary]
25.4
Product Dependencies
25.4.1
I/O Lines
The pins used for interfacing the Static Memory Controller are multiplexed with the PIO lines.
The programmer must first program the PIO controller to assign the Static Memory Controller
pins to their peripheral function. If I/O Lines of the SMC are not used by the application, they can
be used for other purposes by the PIO Controller.
25.4.2
Power Management
The SMC is clocked through the Power Management Controller (PMC), thus the programmer
must first configure the PMC to enable the SMC clock.
25.5
External Memory Mapping
The SMC provides up to 24 address lines, A[23:0]. This allows each chip select line to address
up to 16 Mbytes of memory.
If the physical memory device connected on one chip select is smaller than 16 Mbytes, it wraps
around and appears to be repeated within this space. The SMC correctly handles any valid
access to the memory device within the page (see
Figure 25-1. Memory Connections for Four External Devices
NRD
NWE
A[23:0]
D[7:0]
8
Memory Enable
Memory Enable
Memory Enable
Memory Enable
Output Enable
Write Enable
A[23:0]
D[7:0]
NCS3
NCS0
NCS1
NCS2
NCS[0] - NCS[3]
SMC
24
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