Datasheet

Section 8 EXDMA Controller (EXDMAC)
R01UH0309EJ0500 Rev. 5.00 Page 435 of 1408
Sep 24, 2012
H8S/2456, H8S/2456R, H8S/2454 Group
External memory
Repeated
Repeat area overflow
interrupt can be
requested
Range of
EDSAR values
H'23FFFE
H'23FFFF
H'240000
H'240001
H'240002
H'240003
H'240004
H'240005
H'240006
H'240007
H'240008
H'240009
H'240000
H'240001
H'240002
H'240003
H'240004
H'240005
H'240006
H'240007
:
:
When lower 3 bits (8-byte area) of EDSAR are designated as repeat area
(SARA4 to SARA0 = 3)
Figure 8.9 Example of Repeat Area Function Operation
Caution is required when the repeat area overflow interrupt function is used together with block
transfer mode. If transfer is always terminated when repeat area overflow occurs in block transfer
mode, the block size must be a power of two, or alternatively, the address register value must be
set so that the end of a block coincides with the end of the repeat area range.
If repeat area overflow occurs while a block is being transferred in block transfer mode, the repeat
interrupt request is held pending until the end of the block, and transfer overrun will occur. Figure
8.10 shows an example in which block transfer mode is used together with the repeat area
function.