Ver 1.3
PRELIMINARY
EAGLE
GDMA Descriptor Table
The descriptor includes the information required by DMA controller for data transfer. User should program the descriptor for
each block that needs to be transferred. The programmed descriptors must be connected to each other. After storing the
location of the first descriptor into GDMADT, the DMA controller shall fetch the first programmed descriptor when an
execution command is received. After reading the descriptor, the DMA controller performs data transfer based on the
information found inside the descriptor. The fetch and execution process is repeated after the completion of the last
descriptor. Table 3-7 summarizes the descriptor configuration.
Descriptor field
Description
This field defines the source address needed for DMA transfer. After the DMA controller
reads the descriptor from memory, the value in this field is stored in GDMAS.
This field defines the destination address needed for DMA transfer. After the DMA
controller reads the descriptor from memory, the value in this field is stored in GDMAD.
DMA transfer count. After DMA controller reads the descriptor from memory, the value
of this field is stored in GDMAT.
Source address
Destination address
count
This field defines the start address of the next descriptor in memory. After the DMA
controller reads the descriptor from memory, the value of this field is stored in Next
Descriptor Address Buffer located inside the DMA controller.
This field defines the control status of DMA transfer. After the DMA controller reads the
descriptor from memory, the configuration setting in this field is stored in GDMACON
and in temporary flag buffer.
Next Description address
Control flag
Table 3-7 DMA Descriptor summary
offset
31
0
0x0
0x4
source address
Reserved
0x8
Destination address
Reserved
0xc
0x10
0x14
0x18
0x1c
Count
Next description address
Reserved
Control flag
Figure 3-3 Structure of DMA Descriptor
61
CONFIDENTIAL
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