Datasheet

Section 7 DMA Controller (Not Supported in the H8S/2321)
Rev.6.00 Sep. 27, 2007 Page 239 of 1268
REJ09B0220-0600
Block Transfer Mode
ETCRA
Block Size Storage (ETCRAH)
Bit : 15 14 13 12 11 10 9 8
Initial value : * * * * * * * *
R/W : R/W R/W R/W R/W R/W R/W R/W R/W
Block Size Counter (ETCRAL)
Bit : 7 6 5 4 3 2 1 0
Initial value : * * * * * * * *
R/W : R/W R/W R/W R/W R/W R/W R/W R/W
*: Undefined
ETCRB
Block Transfer Counter
Bit : 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Initial value : * * * * * * * * * * * * * * * *
R/W : R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W
*: Undefined
In block transfer mode, ETCRAL functions as an 8-bit block size counter and ETCRAH holds the
block size. ETCRAL is decremented each time a 1-byte or 1-word transfer is performed, and when
the count reaches H'00, ETCRAL is loaded with the value in ETCRAH. So by setting the block
size in ETCRAH and ETCRAL, it is possible to repeatedly transfer blocks consisting of any
desired number of bytes or words.
ETCRB functions in block transfer mode, as a 16-bit block transfer counter. ETCRB is
decremented by 1 each time a block is transferred, and transfer ends when the count reaches
H'0000.