HD64F2357VF13 Datasheet, PDF (240/1049 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

7.5.7 Block Transfer Mode
In block transfer mode, transfer is performed with channels A and B used in combination. Block transfer mode can be
specified by setting the FAE bit in DMABCR and the BLKE bit in DMACRA to 1.
In block transfer mode, a transfer of the specified block size is carried out in response to a single transfer request, and this
is executed the specified number of times. The transfer source is specified by MARA, and the transfer destination by
MARB. Either the transfer source or the transfer destination can be selected as a block area (an area composed of a
number of bytes or words).
Table 7-11 summarizes register functions in block transfer mode.
Table 7-11 Register Functions in Block Transfer Mode
Register
23
23
MARA
Function
0 Source address
register
Initial Setting
Start address of
transfer source
Operation
Incremented/decremented
every transfer, or fixed
MARB
0 Destination
Start address of Incremented/decremented
address register transfer destination every transfer, or fixed
7
0 Holds block
ETCRAH ^size
Block size
Fixed
Block size
7
0 counter
ETCRAL
15
ETCRB
0 _{Block transfer}
counter
Legend:
MARA: Memory address register A
MARB: Memory address register B
ETCRA: Transfer count register A
ETCRB: Transfer count register B
Block size
Number of block
transfers
Decremented every
transfer; ETCRH value
copied when count reaches
H'00
Decremented every block
transfer; transfer ends
when count reaches
H'0000
MARA and MARB specify the start addresses of the transfer source and transfer destination, respectively, as 24 bits.
MAR can be incremented or decremented by 1 or 2 each time a byte or word is transferred, or can be fixed.
Incrementing, decrementing, or holding a fixed value can be set separately for MARA and MARB.
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 7-13 illustrates operation in block transfer mode when MARB is designated as a block area.
Rev.6.00 Oct.28.2004 page 210 of 1016
REJ09B0138-0600H