Table 7.10 Register Functions In Block Transfer Mode - Renesas H8S/2368 Series Hardware Manual

ETCRB. 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 7.10 summarizes register functions in block transfer mode.

Table 7.10 Register Functions in Block Transfer Mode

Register
23
MARA
23
MARB
7 0
ETCRAH
7 0
ETCRAL
15
ETCRB
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. 2.00, 05/03, page 244 of 820
Function
0
Source address
register
0
Destination
address register
Holds block
size
Block size
counter
0
Block transfer
counter
Initial Setting
Start address of
transfer source
Start address of
transfer destination
Block size
Block size
Number of block
transfers
Operation
Incremented/decremented
every transfer, or fixed
Incremented/decremented
every transfer, or fixed
Fixed
Decremented every
transfer; ETCRH value
copied when count
reaches H'00
Decremented every block
transfer; transfer ends
when count reaches
H'0000