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Whether a block is to be designated for MARA or for MARB is specified by the BLKDIR bit in
DMACRA.
To specify the number of transfers, if M is the size of one block (where M = 1 to 256) and N
transfers are to be performed (where N = 1 to 65,536), M is set in both ETCRAH and ETCRAL,
and N in ETCRB.
Figure 8-13 illustrates operation in block transfer mode when MARB is designated as a block area.
Address T
A
Address B
A
Transfer
Address T
B
Address B
B
1st block
2nd block
Nth block
Block area
Consecutive transfer
of M bytes or words
is performed in
response to one
request
Legend
Address
Address
Address
Address
Where :
= L
A
= L
B
= L
A
+ SAIDE · (–1)
SAID
· (2
DTSZ
· (M·N–1))
= L
B
+ DAIDE · (–1)
DAID
· (2
DTSZ
· (N–1))
= Value set in MARA
= Value set in MARB
= Value set in ETCRB
= Value set in ETCRAH and ETCRAL
T
A
T
B
B
A
B
B
L
A
L
B
N
M
Figure 8-13 Operation in Block Transfer Mode (BLKDIR = 0)