Rev. 1.0, 09/01, page 351 of 904
('5(4
('5(4
('5(4
('5(4
Pin Falling Edge Activation Timing: Figure 8.18 shows an example of normal mode
transfer activated by the
('5(4
pin falling edge.
DMA read
DMA write
ø
Address bus
Write
Idle
Bus release
Transfer
destination
DMA control
Channel
Write
Idle
Transfer source
Transfer source
Bus release
DMA read
DMA write Bus release
Request
Request
[1]
[3]
[2]
[4]
[5]
[6]
[7]
Acceptance
resumed
Acceptance
resumed
Read
Read
Idle
[1]
Acceptance after transfer enabling;
pin low level is sampled at rise of ø, and request is held.
[2], [5] Request is cleared at end of next bus cycle, and activation is started in EXDMAC.
[3], [6] DMA cycle start;
pin high level sampling is started at rise of ø.
[4], [7] When
pin high level has been sampled, acceptance is resumed after completion of write cycle.
(As in [1],
pin low level is sampled at rise of ø, and request is held.)
Transfer
destination
Request clearance period
Request clearance period
Minimum 3 cycles
Minimum 3 cycles
Figure 8.18 Example of Normal Mode Transfer Activated by
('5(4
('5(4
('5(4
('5(4
Pin Falling Edge
('5(4
pin sampling is performed in each cycle starting at the next rise of ø after the end of the
EDMDR write cycle for setting the transfer-enabled state.
When a low level is sampled at the
('5(4
pin while acceptance via the
('5(4
pin is possible,
the request is held within the EXDMAC. Then when activation is initiated within the EXDMAC,
the request is cleared, and
('5(4
pin high level sampling for edge sensing is started. If
('5(4
pin high level sampling is completed by the end of the DMA write cycle, acceptance resumes after
the end of the write cycle, and
('5(4
pin low level sampling is performed again; this sequence
of operations is repeated until the end of the transfer.
Figure 8.19 shows an example of block transfer mode transfer activated by the
('5(4
pin falling
edge.
Содержание H8S/2376 F-ZTAT
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