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System DMA
Constant Addressing Mode
Post-Incremented Addressing Mode
46
Direct Memory Access (DMA) Support
In summary, the general constraints are:
Start address (SA), Element_Index (EI), and Frame_Index (FI) must be
aligned on data type (ES):
SA
mod ES=
(FI-1)
mod ES=
(EI-1)
mod ES=
Address remains constant for each element to be transferred.
A(n+1) = A(n)
where:
A(n): Byte address of the element n within the transfer.
Note:
A(0) is always equal to the start address of the transfer. The same goes for
all addressing modes.
Address is post-incremented by element size (ES).
A(n+1) = A(n) + ES
where:
An: Byte address of the element n within the transfer.
ES: Element size in bytes, ES ∈ {1, 2, 4}.
Figure 6 illustrates how the memory accesses are performed if an LCh is
configured with post-increment addressing mode and:
Starting address: 00
-
Element size: 2 (16 bits)
-
Element number: 2
-
Element index: Ignored
-
Frame number: 2
-
Frame index: Ignored
-
0
0
0
SPRU755B
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