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TC1784
Direct Memory Access Controller (DMA)
User´s Manual
11-45
V1.1, 2011-05
DMA, V3.03
11.2.14
Access Protection
The DMA controller provides an access protection logic that makes it possible to disable
read and write accesses of the Move Engines to specific parts of the memory map. Each
address of a read move and a write move is always checked to determine if it is within
an address range that is enabled for read/write access. If no address range is valid for
an actual move address, a Move Engine interrupt can be generated.
The access protection logic handles two levels of address range definitions:
•
Fixed address range
•
Programmable address range extension
There are 32 fixed address ranges available that can be individually enabled/disabled in
the Move Engine by the address range enable bits AENx (x = 0-31): These bits are
located in the Move Engine 0/1 Access Enable Register ME0AENR/ME1AENR. If bit
AENx is set, read/write accesses to the associated address range x are allowed. If bit
AENx is cleared (default after reset), read/write accesses to the associated address
range x are not executed and a Move Engine interrupt for source or destination move is
generated (see also
Additionall four programmable address range extensions are available for each of the
two Move Engines that are fixed assigned to the OVRAM, the PCP PRAM, the PMI
SPRAM and the DMI LDRAM (see also
). Each programmable address
range extension makes it possible to define a sub-range within the corresponding
address range where an access will be executed by the corresponding Move Engine if
the address range is not disabled by the corresponding AENx bit. An access to the
address range outside the defined sub-range will not be executed by the corresponding
Move Engine. The parameters for the sub-ranges are stored in the Move Engine 0/1
Access Range Register ME0ARR/ME1ARR. The programmable address range
extension is a feature that is applicable for memory access protection of memory blocks.
In such an application, several memory sections are defined as sub-ranges of a
complete memory block.
shows the two levels of address range definitions with the resulting
address sub-ranges of the programmable address range extension. In a fixed address
range, the width of fixed and variable address bits is constant. Number “a” determines
the lowest bit position of the fixed address, and is fixed individually and product-specific
for each of the 32 fixed address ranges. With the programmable address range
extension, the variable address part of the fixed address range definition (as defined by
AENx) is reduced by the definition of a programmable number (up to 32) of sub-ranges.
Bit field ME0ARR.SIZE/ME1ARR.SIZE determines the sub-range size and bit field
ME0ARR.SLICE/ME1ARR.SLICE determines which of the sub-ranges is currently
selected for access protection control. The two parameters (SIZE, SLICE) of the four
address range extensions of a move engine are numbered by index “n” (n = 0-3).
In the TC1784 the number “a” is defined in the followign way:
Содержание TC1784
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