TC1796
System Units (Vol. 1 of 2)
Direct Memory Access Controller
User’s Manual 12-9 V2.0, 2007-07
DMA, V2.0
Figure 12-5 Shadow Source Address and Transfer Count Update
Figure 12-5 shows how the contents of the source address register SADRmn and the
transfer count CHSRmn.TCOUNT are updated during two DMA transactions with a
shadowed source address and transfer count update.
At reference point 2) the DMA transaction 1 is finished and DMA transaction 2 is started.
At 1) the DMA channel is reprogrammed with two new parameters for the next DMA
transaction: Transfer count tc2 and source address sa2. Source address sa2 is buffered
in SADRmn and transferred to SADRmn when the new DMA transaction is started at 2).
At this time, transfer count tc2 is also transferred to CHSRmn.TCOUNT.
tc2
MCT05684_mod
CHSRmn.TCOUNT
tc1 = transfer count 1
tc2 = transfer count 2
sa1 = source address 1
sa2 = source address 2
SHADRmn with
ADRCR0n.SHCT = 01
B
SADRmn
tc1 0
1
tc1-1 tc2 tc2-1 tc2-2
tc1
tc3
sa1
sa1+1 sa2+1 sa2+2sa2
tc1-1
sa1+
tc1
sa1+
sa2 sa3
CHCRmn.TREL
1) 3)2)
1) 3) = writing to CHCRmn and SADRmn
2) = start of new DMA transaction with
shadow transfer of source address
0000 0000
H
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