HD6412320 RENESAS [Renesas Technology Corp], HD6412320 Datasheet - Page 326

• Manufacturer Part Number: HD6412320
• Description: Renesas 16-Bit Single-Chip Microcomputer H8S Family H8S-2300 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

Section 7 DMA Controller (Not Supported in the H8S/2321)
resumes after the end of the single cycle, DREQ pin low level sampling is performed again, and
this operation is repeated until the transfer ends.
DREQ Pin Low Level Activation Timing: Set the DTA bit for the channel for which the DREQ
pin is selected to 1.
Figure 7.32 shows an example of DREQ pin low level activated single address mode transfer.
DREQ pin sampling is performed every cycle, with the rising edge of the next φ cycle after the
end of the DMABCR write cycle for setting the transfer enabled state as the starting point.
Rev.6.00 Sep. 27, 2007 Page 296 of 1268
REJ09B0220-0600
Figure 7.32 Example of DREQ Pin Low Level Activated Single Address Mode Transfer
Address bus
DMA control
[1]
[2] [5] The request is cleared at the next bus break, and activation is started in the DMAC.
[3] [6] The DMAC cycle is started.
[4] [7] Acceptance is resumed after the single cycle is completed.
Note: In write data buffer mode, bus breaks from [2] to [7] may be hidden, and not visible.
Channel
DREQ
DACK
Acceptance after transfer enabling; the DREQ pin low level is sampled on the rising edge of φ,
and the request is held.
(As in [1], the DREQ pin low level is sampled on the rising edge of φ, and the request is held.)
φ
Idle
[1]
Request
Bus release
Minimum of
2 cycles
[2]
[3]
Single
Request clear
Transfer source/
DMA single
destination
period
Acceptance resumes
Idle
[4]
Request
Bus release
Minimum of
2 cycles
[5]
[6]
Single
Request clear
DMA single
Transfer source/
period
destination
Acceptance resumes
Idle
[7]
release
Bus