r4f2456 Renesas Electronics Corporation., r4f2456 Datasheet - Page 410

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

Section 7 DMA Controller (DMAC)
If transfer requests are issued simultaneously for more than one channel, or if a transfer request for
another channel is issued during a transfer, when the bus is released, the DMAC selects the
highest-priority channel from among those issuing a request according to the priority order shown
in table 7.11. During burst transfer, or when one block is being transferred in block transfer, the
channel will not be changed until the end of the transfer. Figure 7.34 shows a transfer example in
which transfer requests are issued simultaneously for channels 0A, 0B, and 1.
Rev. 1.00 Sep. 19, 2008 Page 380 of 1342
REJ09B0467-0100
Address bus
DMA control
Channel 0A
Channel 0B
Channel 1
HWR
LWR
RD
φ
release
Idle
Bus
Request clear
Read
DMA read
Request
hold
Request
hold
Figure 7.34 Example of Multi-Channel Transfer
Write
Channel 0A
transfer
Selection
DMA write
selection
Non-
Idle
release
Request clear
Bus
Read
DMA read
Request
hold
Write
Channel 0B
transfer
Selection
DMA write
Idle
release
Request clear
Bus
Read
DMA read
Channel 1 transfer
Write
DMA write
Read
DMA
read