TC1796
System Units (Vol. 1 of 2)
Direct Memory Access Controller
User’s Manual 12-17 V2.0, 2007-07
DMA, V2.0
12.1.4.6 Transfer Count and Move Count
The move count determines the number of moves (consisting of one read and one write
each) to be done in each transfer. The move count allows the user to indicate to the DMA
the number of moves to be done after one request. The number of moves per transfer is
selected by the block mode settings (CHCRmn.BLKM).
Figure 12-10 Transfer and Move Count
After a DMA move, the next source and destination addresses are calculated. Source
and destination addresses are calculated independently from each other. The following
address calculation parameters can be selected:
• The address offset, which is a multiple of the selected data width
• The offset direction: addition, subtraction, or none (unchanged address)
Control bits in address control register ADRCRmn determine how the addresses are
incremented/decremented. Further, the data width as defined in CHCRmn.CHDW is
taken into account for the address calculation.
Figure 12-11 and Figure 12-12 show two examples of address calculation. In both
examples, a data width of 16-bit (CHCRmn.CHDW = 01
B
) is assumed.
MCT05689
CHSRmn.
TCOUNT
DMA Moves
CHmn_REQ
tc-1 01tc0
tc = initial transfer count
Transfer 0
Transaction
M1 M2 Mx
Transfer 1
M1 M2 Mx
Transfer n
M1 M2 Mx
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