Freescale Semiconductor MCF5480 - Manual (Page 724)

MCF548x Reference Manual, Rev. 3
24-4 Freescale Semiconductor
24.3.1.3 Variable Table
Each task has a private 48-longword variable table. Typically, each variable table must be aligned to a
256-byte boundary, though some may be aligned to a 128-byte boundary if the task uses 32 or less
variables.
24.3.1.4 Function Descriptor Table
Function descriptor tables are 256-byte tables that hold the operation codes to be passed to the DMA
execution units when data manipulation is performed. Each function descriptor table must be aligned to a
256-byte boundary. Each function descriptor table is divided into four 64-byte areas, one for each potential
execution unit. This implementation of the multichannel DMA only contains one execution unit, the
LURC, and it uses the last (fourth) 64-byte area.
24.3.1.5 Context Save Space
Each task has a context save space that the DMA uses to save internal context in when a task is swapped
out of operation. When a task is swapped back into operation, the internal context can be retrieved from
the context save space.
24.3.2 Memory Structure
Each of these memory regions may exist in any addressable storage, such as internal system SRAM or
external memory (internal system SRAM is recommended).
Figure 24-2 illustrates the memory regions that are programmer maintained.