r4f2456 Renesas Electronics Corporation., r4f2456 Datasheet - Page 448

• Manufacturer Part Number: r4f2456
• Description: 16-bit Single-chip Microcomputer H8s Family / H8s/2400 Series
• Manufacturer: Renesas Electronics Corporation.

Section 8 EXDMA Controller (EXDMAC)
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.
Rev. 1.00 Sep. 19, 2008 Page 418 of 1342
REJ09B0467-0100
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
External memory
H'23FFFE
H'23FFFF
H'240000
H'240001
H'240002
H'240003
H'240004
H'240005
H'240006
H'240007
H'240008
H'240009
:
:
EDSAR values
H'240000
H'240001
H'240002
H'240003
H'240004
H'240005
H'240006
H'240007
Range of
Repeated
Repeat area overflow
interrupt can be
requested