r4f2456 Renesas Electronics Corporation., r4f2456 Datasheet - Page 452

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

Section 8 EXDMA Controller (EXDMAC)
(4)
The EDA bit in EDMDR is written to by the CPU to control enabling and disabling of data
transfer, but may be cleared automatically by the EXDMAC due to the DMA transfer status. There
are also periods during transfer when a 0-write to the EDA bit by the CPU is not immediately
effective.
Conditions for EDA bit clearing by the EXDMAC include the following:
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Rev. 1.00 Sep. 19, 2008 Page 422 of 1342
REJ09B0467-0100
When the EDTCR value changes from 1 to 0, and transfer ends
When a repeat area overflow interrupt is requested, and transfer ends
When an NMI interrupt is generated, and transfer halts
A reset
Hardware standby mode
When 0 is written to the EDA bit, and transfer halts
EDA Bit in EDMDR
EDTCR in normal transfer mode
EDTCR
EDTCR
EDTCR in block transfer mode
EDTCR
EDTCR
Figure 8.11 EDTCR Update Operations in Normal Transfer Mode and
23
23
23
23
Block
Block
size
size
16
16
1 to H'FFFFFF
Before update
Before update
15
15
0
1 to H'FFFF
Block Transfer Mode
0
0
0
0
0
Fixed
Fixed
–1
–1
23
23
23
23
Block
Block
size
size
16
16
0 to H'FFFFFE
After update
After update
15
15
0
0 to H'FFFE
0
0
0
0
0