HD6412373R RENESAS [Renesas Technology Corp], HD6412373R Datasheet - Page 465

• Manufacturer Part Number: HD6412373R
• Description: Renesas 16-Bit Single-Chip Microcomputer H8S Family/H8S/2300 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

[1]
[2], [5] Request is cleared at end of next bus cycle, and activation is started in EXDMAC.
[3], [6] DMA cycle start; EDREQ pin high level sampling is started at rise of φ.
[4], [7] When EDREQ pin high level has been sampled, acceptance is resumed after completion of dead cycle.
EDREQ pin sampling is performed in each cycle starting at the next rise of φ after the end of the
EDMDR write cycle for setting the transfer-enabled state.
When a low level is sampled at the EDREQ pin while acceptance via the EDREQ pin is possible,
the request is held within the EXDMAC. Then when activation is initiated within the EXDMAC,
the request is cleared, and EDREQ pin high level sampling for edge sensing is started. If EDREQ
pin high level sampling is completed by the end of the DMA write cycle, acceptance resumes after
the end of the write cycle, and EDREQ pin low level sampling is performed again; this sequence
of operations is repeated until the end of the transfer.
φ
EDREQ
Address bus
DMA control
Channel
Figure 8.19 Example of Block Transfer Mode Transfer Activated by EDREQ Pin Falling
Acceptance after transfer enabling; EDREQ pin low level is sampled at rise of φ, and request is held.
(As in [1], EDREQ pin low level is sampled at rise of φ, and request is held.)
Idle
[1]
Minimum 3 cycles
Bus release
Request
[2]
Read
Request clearance period
[3]
Transfer source
DMA read
One block transfer
Write
DMA write
destination
Transfer
Edge
Acceptance
resumed
Idle
[4]
Minimum 3 cycles
Request
Bus release
Rev.7.00 Mar. 18, 2009 page 397 of 1136
Section 8 EXDMA Controller (EXDMAC)
[5]
Request clearance period
Read
[6]
Transfer source
DMA read
One block transfer
Write
DMA write Bus release
REJ09B0109-0700
destination
Transfer
Acceptance
resumed
Idle
[7]