R5S72011 RENESAS [Renesas Technology Corp], R5S72011 Datasheet - Page 386

• Manufacturer Part Number: R5S72011
• Description: 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7200 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

Section 11 Direct Memory Access Controller (DMAC)
If the DMA transfer is not done sequentially, the DMA request must be canceled within three
cycles after the end of single operand transfer.
(2)
When an edge sense is specified (STRG = "00" or "10"), the rising or falling edge of the DMA
request signal indicates a DMA request.
When the selected edge is detected, the DMA request bit (DREQ) in the DMA control register B
(DMCNTBn) is set to "1". After that, the value in the DMA request bit (DREQ) is retained
regardless of shifts in the level of the DMA request signal. After the DMA request has been
accepted and the DAM acknowledge signal output, the DMA request bit (DREQ) is automatically
cleared to "0".
Since DMA requests are internally retained for a channel in edge sense mode, further occurrences
of the selected edge of the DMA request signal are ignored since the DMA request bit (DREQ)
has already been set back to "1".
Figure 11.9 is an example of DMA request reception processing when an edge sense is selected.
Rev. 2.00 Sep. 07, 2007 Page 358 of 1164
REJ09B0321-0200
System clock
DMA state
DMA request input
(falling edge sense)
DMA acknowledge
output
DMA request bit
[Legend]
: Sampling point for DMA requests
The DMA request bit is set on detection of the selected edge.
The DMA request is thus maintained despite further changes
in the level of the DMA request signal.
Edge sense
Figure 11.9 Example of DMA Request Reception Processing
When the DMA request is accepted, the DMA acknowledge
signal is activated and the DMA request bit is cleared.
when an Edge Sense is Selected
Read
The DMA request bit is set on detection of the selected edge.
The DMA request is thus maintained despite further changes
in the level of the DMA request signal.
Start of single operand transfer
Write
Read