Linking EDMA Transfers
6-25
EDMA Controller
6.9
Linking EDMA Transfers
The EDMA controller provides a mechanism known as ‘linking’, which allows
multiple EDMA transfers to be linked. The completion of one transfer links the
next transfer in a link causing its event parameters to be loaded from a location
within the parameter RAM. This feature is especially useful for complex sort-
ing, circular buffering type of applications. The 16-bit link address field in the
EDMA parameter RAM and the LINK bit in the options field is used for this pur-
pose. The link address points to the next transfer entry location in the linked
list. The entire EDMA parameter RAM is located in the 01A0 xxxxh area.
Therefore the 16-bit link address, which corresponds to the lower 16-bit
physical address, is sufficient to specify the location of the next transfer entry.
The link address must be aligned on a 24-byte boundary. An example of a
linked EDMA transfer is shown in Figure 6–13.
Figure 6–13. Linked EDMA Transfer
Event N parameters
Reload parameters at
01A0 0180
Options (LINK=1)
Src address
Frame count
Element
count
Dst address
Frame index
Element
index
Elem. count
reload
Link address
0180h
Options (LINK=1)
Src address
Frame count
Element
count
Dst address
Frame index
Element
Index
Elem. count
reload
Link address
01B0h
Reload parameters at
01A0 01B0
Options (LINK=0)
Src address
Frame count
Element
count
Dst address
Frame index
Element
index
Elem. count
reload
Link address =
don’t care